COMP 051

Welcome
Introduction to Computer Science

Week	Meeting Dates (TR)	Topic	Notes	Assignments
Week 1	Aug 26, Aug 28	Course Overview, What is a Program?, First C++ Program
Week 2	Sep 2, Sep 4	Variables and Basic I/O	Sep 1 is Labor Day – no Monday classes	Lab/H2 #1
Week 3	Sep 9, Sep 11	Branches
Week 4	Sep 16, Sep 18	Loops		Lab/H2 #2
Week 5	Sep 23, Sep 25	Array/Vectors
Week 6	Sep 30, Oct 2	User Defined Functions	Oct 3 is Fall Student Break	Lab/H2 #3
Week 7	Oct 7, Oct 9	Objects and Classes
Week 8	Oct 14, Oct 16	Classes and Inheritance		Midterm Exam: Oct. 16th, Lab/HW2 #4
Week 9	Oct 21, Oct 23	Classes and Inheritance
Week 10	Oct 28, Oct 30	Data Streams		Lab/H2 #5
Week 11	Nov 4, Nov 6	Exceptions
Week 12	Nov 11, Nov 13	Recursion and Module Review		Lab/H2 #6
Week 13	Nov 18, Nov 20	Module Review
Week 14	Nov 25 ~~Nov 27~~ (Thanksgiving)	Finals Preparation	No class Nov 27	Lab/H2 #7 (due Nov 25)
Week 15	Dec 2, Dec 4	Final Review, Student Demos, Course Wrap-up	Final project presentations or quiz
Week 16	Dec 9	Final Exam Period		Final Exam: Dec. 9th at 3PM in Baun 214

Before Operating Systems

1940s–1950s: Computers programmed with switches, punch cards, or raw machine code.
Each program controlled the whole machine: no sharing, no multitasking.
Programmers had to include code to handle devices and stop/start jobs manually.
Very slow, error-prone.

Bell Labs and AT&T

Bell Labs was the research arm of AT&T (founded 1925).
In the late 1960s, they needed an operating system to manage computers for communication networks (manage = schedule programs, allocate CPU & memory, control devices, share files).
1969–1971: Led to the creation of UNIX as a flexible system for research and telecom needs.

History of C

Early 1970s at Bell Labs (Dennis Ritchie)
System programming for UNIX

Why C?

Close to hardware, portable
Small runtime, fast compilation

C Code


int add(int a, int b) {
    return a + b;
}

Assembly


add:
    mov eax, edi    ; move a into eax
    add eax, esi    ; add b (esi) to eax
    ret             ; return result

x86-64 System V calling convention

Machine Code


55                ; push rbp
89 f8             ; mov eax, edi
01 f0             ; add eax, esi
5d                ; pop rbp
c3                ; ret

Compiled with gcc -O1 on x86-64

How C Becomes Machine Code

C Code
int add(int a, int b)

→

Compiler
(gcc, clang, etc.)

→

Assembly Code
mov eax, edi

→

Assembler
(part of toolchain)

→

Machine Code
55 89 f8 01 f0 5d c3

Source: Visualized compilation process from C to machine code

Start Engine (C Code)


#include <stdio.h>

// Simulated function to start engine
void start_engine() {
    printf("Connecting to engine...\n");
    // Simulate hardware I/O or network call
    printf("Engine started successfully!\n");
}

int main() {
    start_engine();
    return 0;
}

History of C++

1980s: Bjarne Stroustrup
“C with Classes” → C++

Why C++?

Object‑oriented programming
Performance with abstraction

Basic I/O

#include <iostream>
int main(){
  int age; 
  std::cout << "Age? ";
  std::cin >> age;
  std::cout << "You are " << age << "\n";
}

Variables

int count = 5; 
double pi = 3.14159; 
char grade = 'A'; 
std::string name = "Alice";

Expressions

int a = 10, b = 3; 
int sum = a + b; 
int product = a * b; 
double avg = (a + b) / 2.0;

Decisions

if (score >= 90) {
  std::cout << "Excellent!";
} else {
  std::cout << "Keep going!";
}

Loops: for

for (int i = 1; i <= 5; ++i) {
  std::cout << i << " ";
}

Loops: while

int n = 5;
while (n > 0) {
  std::cout << n-- << " ";
}

Functions

int square(int x){ return x * x; }
int main(){ std::cout << square(5); }

Arrays

int nums[3] = {10, 20, 30};
for (int i = 0; i < 3; ++i)
  std::cout << nums[i] << " ";

Strings

#include <string>
std::string s = "Pacific";
std::cout << s.size();
std::cout << s[0];

Classes (C++)

class Student {
public:
  std::string name; int id;
};
Student s; s.name = "Bob"; s.id = 102;

How This Course Runs

Weekly labs + practice
Concept → code → feedback
Ask questions early & often

Today, Thursday Aug 28th

Develop C++ Caclulator
Develop C++ Game
Introduction to zyBook
Homework 1 and Lab 1

Develop C++ Caclulator


#include <iostream>
using namespace std;

int main() {
    double a, b;
    char op;

    // TODO: read a, op, b
    // TODO: compute and print result

    return 0;
}


cout << "Enter expression (e.g., 5 * 2): ";
cin >> a >> op >> b;


switch (op) {
    case '+': cout << (a + b) << "\n"; break;
    case '-': cout << (a - b) << "\n"; break;
    case '*': cout << (a * b) << "\n"; break;
    case '/':
        if (b == 0) cout << "Error: division by zero\n";
        else cout << (a / b) << "\n";
        break;
    default:
        cout << "Unknown operator\n";
}


#include <iostream>
using namespace std;

int main() {
    double a, b;
    char op;

    cout << "Enter expression (e.g., 5 * 2): ";
    if (!(cin >> a >> op >> b)) {
        cout << "Input error\n";
        return 0;
    }

    switch (op) {
        case '+': cout << (a + b) << "\n"; break;
        case '-': cout << (a - b) << "\n"; break;
        case '*': cout << (a * b) << "\n"; break;
        case '/':
            if (b == 0) cout << "Error: division by zero\n";
            else cout << (a / b) << "\n";
            break;
        default:
            cout << "Unknown operator\n";
    }

    return 0;
}

Questions?

Today, Thursday Aug 28th

Develop C++ Caclulator ✓
Develop C++ Game
Introduction to zyBook
Homework 1 and Lab 1

#include <iostream>
#include <cstdlib>
#include <ctime>
using namespace std;

int main() {
    srand(time(0));
    int player, computer;
    cout << "Enter 0=Rock, 1=Paper, 2=Scissors: ";
    cin >> player;
    computer = rand() % 3;

cout << "Computer chose: " << computer << endl;
if(player == computer) cout << "Draw!\n";

else if((player==0 && computer==2) ||
        (player==1 && computer==0) ||
        (player==2 && computer==1))
    cout << "Player wins!\n";

else
    cout << "Computer wins!\n";
return 0;

// Optional: map numbers to names
string choices[] = {"Rock", "Paper", "Scissors"};
cout << "Player chose: " << choices[player] << ", Computer chose: " << choices[computer] << endl;

// Full program copy/paste
#include <iostream>
#include <cstdlib>
#include <ctime>
using namespace std;

int main() {
    srand(time(0));
    int player, computer;
    string choices[] = {"Rock", "Paper", "Scissors"};

    cout << "Enter 0=Rock, 1=Paper, 2=Scissors: ";
    cin >> player;
    computer = rand() % 3;

    cout << "Player chose: " << choices[player] << ", Computer chose: " << choices[computer] << endl;

    if(player == computer) cout << "Draw!\n";
    else if((player==0 && computer==2) ||
            (player==1 && computer==0) ||
            (player==2 && computer==1))
        cout << "Player wins!\n";
    else
        cout << "Computer wins!\n";

    return 0;
}

// Optional: loop for multiple rounds
for(int i=0;i<3;i++) {
    // repeat input, generate computer move, decide winner
}

// Optional: add input validation
if(player <0 || player >2) cout << "Invalid choice!\n";

Questions?

Today, Tuesday Nov. 18th

Introduction to Variables
Variable Declaration
Variable Initialization
Assignment
Reassignment
Hands-On Practice
Variable Memory Size
Constants, Casting, etc.
Basic Input Output (I/O)
Homework 1 and Lab 1

Introduction to Variables

Variables store data in memory
Each variable has a type and a name
Used to hold values for processing


int age = 18;
float price = 19.99;
double pi = 3.14159;
char grade = 'A';
bool passed = true;
string name = "Alice";

Quiz: Introduction

A) Variables store data in memory
B) Variables are constants
C) Variables are functions
D) Variables are keywords


int score = 90;
cout << "Score: " << score;

Common Data Types

int → whole numbers
float, double → decimals
char → single characters
bool → true/false
string → text


int students = 25;
float height = 5.9f;
double salary = 50000.75;
char initial = 'B';
bool isActive = false;
string city = "Stockton";

Quiz: Data Types

A) int number = 10;
B) float 2price = 19.99;
C) char = 'A';
D) bool = true;


// Correct variable
int number = 10;
cout << "Number: " << number;

Key Takeaways

Variables must be declared before use
Each has a type and name
Used to store and process data


string name = "John";
cout << "Hello, " << name;

Variable Declaration

Declare variables without assign value
Syntax: type name;
Example: int, float, char, bool, string


int count;
float temperature;
double distance;
char letter;
bool isReady;
string message;

Quiz: Declaration

A) int x;
B) float 2price;
C) char initial;
D) bool done;


// Valid declaration
float temp;
temp = 36.5f;
cout << "Temperature: " << temp;

Multiple Declarations

Declare multiple variables, same type
Syntax: int a, b, c;
Assign values later if needed


int x, y, z;
x = 5;
y = 10;
z = 15;
cout << x + y + z;

Quiz: Multiple Declaration

A) int a, b, c;
B) float 2x, y, z;
C) char = 'A';
D) bool flag;


// Valid multiple declaration
int a, b, c;
a = 1; b = 2; c = 3;
cout << a + b + c;

Key Takeaways

Declare variables before use
Can declare multiple variables at once
Assign values later


int score, level;
score = 10;
level = 1;
cout << "Score: " << score << ", Level: " << level;

Variable Initialization

Assign value to variable when declared
Simplify code + avoids garbage values
Works with all basic data types


int age = 20;
float height = 5.8f;
double pi = 3.14159;
char grade = 'B';
bool isPassed = true;
string name = "Bob";

Quiz: Initialization

A) int x;
B) float y = 9.5;
C) char;
D) bool flag;


// Correct initialization
float y = 9.5;
cout << "Value: " << y;

Initialization Tips

Initialize variables at declaration time
Avoids undefined behavior
✓ int, float, double, char, bool, string


int count = 10;
double distance = 12.5;
char initial = 'C';
bool done = false;
string city = "LA";

Quiz: Tips

A) int x;
B) double distance = 12.5;
C) char;
D) bool;


// Correct example
double distance = 12.5;
cout << "Distance: " << distance;

Key Takeaways

Initialize variables, no garbage values
Simplifies code and debugging
Applicable to all basic types


int age = 25;
float price = 19.99;
string name = "Alice";
cout << "Age: " << age << ", Price: " << price;

Assignment

Assign a value to an existing variable
Can happen anytime after declaration
Works with all types: int, float, double, char, bool, string


int score;
score = 95;
float temp;
temp = 36.6f;
char grade;
grade = 'A';
bool passed;
passed = true;
string name;
name = "Bob";

Quiz: Assignment

A) int x = 5;
B) int x; x = 5;
C) float y;
D) char c;


// Assignment example
int x;
x = 5;
cout << "X: " << x;

Multiple Assignments

Assign values to variables separately
Keep code readable


int a, b;
a = 10;
b = 20;
float temp, height;
temp = 36.5f;
height = 5.9f;

Quiz: Multiple Assignment

A) int a, b; a=5; b=10;
B) float x, y; x=; y=20;
C) char c; c;
D) bool flag;


// Multiple assignment example
int a, b;
a = 5;
b = 10;
cout << a + b;

Key Takeaways

Assign values anytime after declaration
Works for all basic types
Improves readability and debugging


string name;
name = "Alice";
int age;
age = 25;
cout << name << " is " << age << " years old";

Reassignment

Change value of an variable
Previous value is overwritten
Applicable to all types


int score = 50;
score = 75;
float temp = 36.5f;
temp = 37.0f;
char grade = 'B';
grade = 'A';
bool passed = false;
passed = true;
string name = "Bob";
name = "Alice";

Quiz: Reassignment

A) int x = 5; x = 10;
B) float y;
C) char c;
D) bool flag;


// Reassignment example
int x = 5;
x = 10;
cout << x;

Tips for Reassignment

Use meaningful variable names
Keep track of current value
Reassignment can happen many times


int score = 50;
score = 70;
score = 90;
cout << "Final score: " << score;

Quiz: Tips

A) int x = 10; x = 20;
B) float y;
C) char c;
D) bool flag;


// Multiple reassignment
int x = 10;
x = 20;
x = 30;
cout << x;

Key Takeaways

Reassignment changes variable values
Overwrites previous value
Use meaningful names and keep track


int score = 50;
score = 75;
score = 100;
cout << "Final Score: " << score;

Introduction to Variables ✓
Variable Declaration ✓
Variable Initialization ✓
Assignment ✓
Reassignment ✓
Hands-On Practice
Variable Memory Size
Constants, Casting, etc.
Basic Input Output (I/O)
Homework 1 and Lab 1

Hands-On Practice 1

John is 21 years old. Define a variable to store his age and initialize it with the correct value.


// Define variable type and initialize

Hands-On Practice 2

The room temperature is 23.5 degrees Celsius. Create a variable to store the temperature.


// Define variable type and initialize

Hands-On Practice 3

The student received a grade 'A' in the exam. Define a variable to store the grade.


// Define variable type and initialize

Introduction to Variables ✓
Variable Declaration ✓
Variable Initialization ✓
Assignment ✓
Reassignment ✓
Hands-On Practice ✓
Variable Memory Size
Constants, Casting, etc.
Basic Input Output (I/O)
Homework 1 and Lab 1

Memory Size: int

Stores whole numbers
Typically 4 bytes (depends on system)
Range: -2,147,483,648 to 2,147,483,647


#include <iostream>
using namespace std;

int main() {
    cout 
        << "Size of int: " 
        << sizeof(int) 
        << " bytes\n";
}

Memory Size: float

Stores decimal numbers
Typically 4 bytes
Approximate precision: 6–7 digits


#include <iostream>
using namespace std;

int main() {
    cout 
        << "Size float: " 
        << sizeof(float) 
        << " bytes\n";
}

Memory Size: double

Stores decimal numbers with higher precision
Typically 8 bytes
Approximate precision: 15–16 digits


#include <iostream>
using namespace std;

int main() {
    cout 
        << "Size of double: " 
        << sizeof(double) 
        << " bytes\n";
}

Memory Size: char

Stores a single character
Typically 1 byte
Range: -128 to 127 (signed)


#include <iostream>
using namespace std;

int main() {
    cout 
        << "Size of char: " 
        << sizeof(char) 
        << " bytes\n";
}

Memory Size: bool

Stores true or false
Typically 1 byte
0 = false, 1 = true


#include <iostream>
using namespace std;

int main() {
    cout 
        << "Size of bool: " 
        << sizeof(bool) 
        << " bytes\n";
}

Memory Size: string

Stores text of variable length
Size depends on implementation and length of content
Typically more than the length of characters due to overhead


#include <iostream>
#include <string>
using namespace std;

int main() {
    string name = "Alice";
    cout 
        << "Size of string object: " 
        << sizeof(name) 
        << " bytes\n";
}

Introduction to Variables ✓
Variable Declaration ✓
Variable Initialization ✓
Assignment ✓
Reassignment ✓
Hands-On Practice ✓
Variable Memory Size ✓
Constants, Casting, etc.
Basic Input Output (I/O)
Homework 1 and Lab 1

Constants (const)

Variables that cannot be changed after initialization
Useful for fixed values like PI or max limits
Helps prevent accidental modification


const double PI = 3.14159;
const int MAX_STUDENTS = 50;
cout << "PI: " << PI << ", Max: " << MAX_STUDENTS;

Type Modifiers

Change size or sign of data types
Common modifiers: short, long, unsigned
Useful for memory optimization or larger ranges


unsigned int count = 100;
long distance = 100000L;
short smallNumber = 10;
cout << count << ", " << distance << ", " << smallNumber;

Type Casting / Conversion

Convert a variable from one type to another
Implicit vs explicit casting
Helps when performing calculations with different types


int x = 10;
double y = (double)x; // explicit cast
float z = x;           // implicit cast
cout << y << ", " << z;

Input & Output

Use cin to read values from user
Use cout to display values
Works with all basic data types


int age;
cout << "Enter your age: ";
cin >> age;
cout << "Your age is: " << age;

Scope & Lifetime of Variables

Local variables exist only inside a function/block
Global variables exist throughout the program
Helps manage memory and avoid conflicts


int globalVar = 100; // global

void func() {
    int localVar = 50; // local
    cout << localVar;
}

int main() {
    cout << globalVar;
    func();
}

Default Values

Uninitialized variables may contain garbage
Always initialize variables to avoid undefined behavior
Applies to int, float, double, char, bool, string


int a;       // may have garbage value
float b;     // may have garbage
int c = 0;   // safe initialization
float d = 0; // safe initialization

Enumerations (enum)

Define a set of named integer constants
Improves code readability
Use for categories, options, or states


enum Color { RED, GREEN, BLUE };
Color c = RED;
cout << c; // prints 0 for RED

Pointers (Intro)

Store memory addresses of variables
Useful for dynamic memory and efficient data handling
Introductory concept for later lessons


int x = 10;
int* ptr = &x; // pointer stores address of x
cout << "Address: " << ptr;
cout << "Value: " << *ptr;

Introduction to Variables ✓
Variable Declaration ✓
Variable Initialization ✓
Assignment ✓
Reassignment ✓
Hands-On Practice ✓
Variable Memory Size ✓
Constants, Casting, etc.✓
Basic Input Output (I/O)
Homework 1 and Lab 1

Basic IO: Introduction

cin and cout are used for input and output
cin reads data from user
cout prints data to console
Part of iostream library


#include <iostream>
using namespace std;

int main() {
    int age;
    cout << "Enter your age: ";
    cin >> age;
    cout << "Your age is " << age;
}

Input Multiple Variables

cin can read several variables at once
Values are separated by spaces
Works for int, float, char, string


#include <iostream>
#include <string>
using namespace std;

int main() {
    int age;
    float height;
    string name;

    cout << "Enter name, age, height: ";
    cin >> name >> age >> height;

    cout << name << " is " << age << " years old, "
         << height << " m tall";
}

Formatted Output

Use endl for new lines
<< operator concatenates outputs
Useful for clear console messages


#include <iostream>
using namespace std;

int main() {
    int x = 10, y = 20;
    cout << "X = " << x << endl;
    cout << "Y = " << y << endl;
    cout << "Sum = " << (x+y) << endl;
}

Input Validation

Check if the user enters the correct type
cin.fail() can detect input errors
Helps avoid garbage values or crashes


#include <iostream>
using namespace std;

int main() {
    int age;
    cout << "Enter age: ";
    cin >> age;

    if(cin.fail()) {
        cout << "Invalid input!";
    } else {
        cout << "Age: " << age;
    }
}

Input & Output with Strings

Use getline() for multi-word strings
cin reads only up to first space
cout prints the string normally


#include <iostream>
#include <string>
using namespace std;

int main() {
    string fullName;
    cout << "Enter full name: ";
    getline(cin, fullName);
    cout << "Hello, " << fullName;
}

Introduction to Variables ✓
Variable Declaration ✓
Variable Initialization ✓
Assignment ✓
Reassignment ✓
Hands-On Practice ✓
Variable Memory Size ✓
Constants, Casting, etc.✓
Basic Input Output (I/O) ✓
Homework 1 and Lab 1

Today, Thursday Sept 4th

Introduction to Variable Naming
Team Formation & Game Rules
Homework 1 and Lab 1 Overview

Introduction to Variable Naming

Good variable names improve readability
Reduces errors and improves maintainability
Follow clear conventions for consistency


// Example of descriptive names
int age = 20;
float heightInMeters = 1.75;
bool isRegistered = true;

Basic Rules

Names must start with a letter or underscore (_)
Cannot start with a digit
No special characters except underscore


// Valid names
int _count;
float totalAmount;
// Invalid names
// int 2ndValue;
// char first-name;

Case Sensitivity

Variable names are case-sensitive
age and Age are different
Follow consistent capitalization style


int age = 20;
int Age = 30; // separate variable

Meaningful Names

Describe purpose of the variable
Avoid generic names like temp or val
Helps others understand your code


int s;         // unclear
int score;     // clear
float t;       // unclear
float temperature; // clear

Naming Styles

camelCase: totalAmount
snake_case: total_amount
PASCALCase: TotalAmount (commonly for classes)
Be consistent across the project


// camelCase
int studentCount;
// snake_case
int student_count;
// PASCALCase (class example)
class StudentInfo {};

Boolean Variables

Use names that clearly represent true/false
Common prefixes: is, has, can
Helps readability in conditions


bool isRegistered = true;
bool hasAccess = false;
bool canVote = true;

if(isRegistered) {
    cout << "User registered.";
}

Avoid Reserved Keywords

C++ keywords cannot be used as variable names
Examples: int, float, class, return
Use descriptive alternatives


// Invalid
// int class = 10;
// float return = 5.5;
// Valid
int classCount;
float returnValue;

Length of Variable Names

Too short: unclear (x, y)
Too long: cumbersome (totalSumOfMonthlyTransactions)
Balanced: descriptive yet concise (totalSum)


int x;               // bad
int totalSumOfMonth; // too long
int totalSum;        // good

Global vs Local Variables

Use clear prefixes for global variables (g_)
Local variables should be descriptive within their function
Reduces confusion and conflicts


int g_totalUsers = 0; // global
void registerUser() {
    int localScore = 0; // local
}

Default Values

Always initialize variables to avoid garbage values
Applies to all types: int, float, char, bool, string
Helps prevent undefined behavior


int score = 0;
float temperature = 0.0f;
bool isActive = false;
string name = "";
char grade = 'A';

Constants

Variables that cannot be changed after initialization
Use UPPERCASE naming for constants
Helps distinguish from normal variables


const double PI = 3.14159;
const int MAX_USERS = 50;
cout << "PI: " << PI << ", Max: " << MAX_USERS;

Type Modifiers

short, long, unsigned modify size or sign
Helps memory optimization or larger ranges
Include in variable names if necessary


unsigned int count = 100;
long distance = 100000L;
short smallNumber = 10;
cout << count << ", " << distance << ", " << smallNumber;

Type Casting

Explicit: (double)x
Implicit: automatic conversion
Use descriptive names if casting result differs in purpose


int x = 10;
double y = (double)x; // explicit cast
float z = x;           // implicit cast
cout << y << ", " << z;

Scope & Lifetime

Local: exists inside a block/function
Global: exists throughout the program
Name variables clearly to reflect scope


int g_counter = 0; // global
void func() {
    int localCounter = 5; // local
    cout << localCounter;
}
cout << g_counter;

Summary: Best Practices

Start with a letter or underscore
Use meaningful, descriptive names
Follow a consistent style: camelCase or snake_case
Boolean variables: use is/has/can prefixes
Constants in UPPERCASE
Always initialize variables


// Example
int studentCount = 50;
bool isRegistered = true;
const int MAX_USERS = 100;
float temperature = 36.5f;

Questions?

Welcome & Game Briefing

Today's topic: Variables in C++. Teams will compete in quizzes, coding relays, and challenges!

Team Formation

Form 2–3 teams (3–5 members each). Pick a team name and captain.

Game Rules

Correct answer: +10 points
Wrong answer: -5 points
Bonus challenge: +15 points

Scoreboard

Team Red: 0 | Team Blue: 0 | Team Green: 0

Concept: What is a Variable?

A variable stores data that can change during program execution.

Quiz: Identify Valid Declaration

A) int 5x;
B) int x5;
C) int x=;
D) int;x=5;

Challenge: Declare Correctly


// Declare an integer named 'age'

Bonus Round: Declare 3 Types


// Declare int, float, char in one line

Quiz: Which is Correct Initialization?

A) int x = 10;
B) int x == 10;
C) int x;

Quiz: Boolean Naming

A) bool registered;
B) bool isRegistered;
C) bool 1Registered;

Quiz: Valid Variable Names

A) int _count;
B) int 2count;
C) int count!;

Quiz: Reserved Words

A) int float;
B) int value;
C) char return;

Quiz: Case Sensitivity

Which statement is correct?

A) int age = 5; int Age = 6;
B) int age = 5; int age = 6;
C) int Age = 5; int Age = 6;

Quiz: Constants Naming

A) const int MAX = 100;
B) const int max = 100;
C) int MAX = 100;

Quiz: Default Value

What is the default value of an uninitialized bool in C++?

Quiz: Float vs Double

Which type has higher precision?

A) float
B) double

Quiz: Type Modifiers

Which is correct to store only positive values?

A) int a;
B) unsigned int a;
C) long int a;

Quiz: Swap Variables


// Swap a=5, b=10 using arithmetic

Quiz: Variable Scope


int x = 5;
{
  int x = 10;
}
cout << x;

Quiz: Variable Shadowing

What happens if a local variable has the same name as a global variable?

A) Error
B) Local variable overrides global inside scope
C) Global variable overrides local

Quiz: Implicit Conversion

What is the type of int x = 5; double y = x;?

A) int to double (implicit)
B) double to int (explicit)

Quiz: Initialization vs Assignment

A) int x = 5; // initialization
B) x = 10; // assignment
C) Both A & B

Quiz: Naming Boolean Variables

A) bool flag;
B) bool isReady;
C) bool 0Ready;

Quiz: Valid Identifiers

A) int myVar;
B) int 2myVar;
C) int my-Var;

Quiz: Constants Correct Syntax

A) const int MAX = 10;
B) const int MAX;
C) int const MAX;

Quiz: Memory Sizes

A) char – 1 byte
B) int – 4 bytes
C) double – 8 bytes
D) All of the above

Quiz: Input/Output

Which line reads an integer from the user?

A) cin >> x;
B) cout << x;
C) scanf("%d", x);

Quiz: Swap Variables Correctly


// Swap x=3 and y=5 using a temporary variable

Lightning Round

5 quick questions: each worth +5 points.

Q1: Valid Variable Name?

A) int 1value;
B) int value1;
C) int value-1;

Q2: Boolean Initialization

A) bool flag = true;
B) bool flag = 1;
C) bool flag = "true";

Q3: Correct Constant Declaration

A) const int MAX = 100;
B) const int MAX;
C) int const MAX;

Q4: Default Value of uninitialized int?

A) 0
B) Garbage / undefined
C) 1

Q5: Output of this code?


int x = 5;
{
    int x = 10;
}
cout << x;

Team Discussion

When to use constants vs variables?

Scoreboard Update

Team Red: __ | Team Blue: __ | Team Green: __

Recap & Key Takeaways

Variables store changeable data
Constants prevent modification
Memory size matters
Input/Output via cin/cout

Final Quiz

Mixed questions on all topics.

Identify and fix the syntax error in this code.


int main() {
    int x
    x = 10;
    cout << x;
    return 0;
}

Answer: Missing semicolon after int x.

This code may crash. Find the problem and fix it.


int main() {
    int a = 5, b = 0;
    int c = a / b;
    cout << c;
    return 0;
}

Answer: Division by zero. Ensure b != 0 before dividing.

The program prints incorrectly. Fix the variable scope.


int main() {
    if (true) {
        int x = 10;
    }
    cout << x;
    return 0;
}

Answer: x is out of scope. Declare it before the if-block.

Homework & Lab

Homework 1 and Lab 1 details shared with teams.

Winner Announcement

Congratulations to the winning team!

Today, Tuesday Sept 9th

What is a branch?
Decision-making in programs
Real-world example
if / else statements in C++
switch statements in C++
Homework and Lab

What is a Branch?

Programs need to make choices
Branches control the program flow
Initial check: Determine if the printer has paper before printing
Example: Printer checks paper tray

bool paperTrayFull = true;
if (paperTrayFull) {
    cout << "Ready to print";
}

What is a Branch?

Branches allow programs to respond differently
Initial check: Is printer online before sending a job?
Prevents errors like printing without power

bool printerOnline = false;
if (printerOnline) {
    cout << "Sending print job...";
} else {
    cout << "Printer offline!";
}

What is a Branch?

Branches evaluate conditions
Initial check: Is toner available?
Prevents printing blank pages

bool tonerAvailable = true;
if (tonerAvailable) {
    cout << "Printing document...";
} else {
    cout << "Refill toner first";
}

What is a Branch?

Branches help decision-making in sequence
Initial check: Paper type suitable for print job?
Ensures correct quality output

string paperType = "A4";
if (paperType == "A4") {
    cout << "Proceed with print";
} else {
    cout << "Insert correct paper size";
}

What is a Branch?

Branches allow error handling
Initial check: Is printer jammed?
Prevents damage and wasted pages

bool printerJam = true;
if (printerJam) {
    cout << "Clear the jam first";
} else {
    cout << "Ready to print";
}

What is a Branch?

Branches support conditional notifications
Initial check: Low ink warning
Prevents unfinished print jobs

bool inkLow = true;
if (inkLow) {
    cout << "Warning: Refill ink";
} else {
    cout << "Ink level sufficient";
}

What is a Branch?

Branches allow conditional logging
Initial check: Has a job been queued?
Helps track printer usage

bool jobQueued = true;
if (jobQueued) {
    cout << "Processing queued job";
} else {
    cout << "No jobs pending";
}

What is a Branch?

Branches check preconditions before execution
Initial check: Printer cover closed?
Ensures safe operation

bool coverClosed = false;
if (coverClosed) {
    cout << "Printer ready";
} else {
    cout << "Close the cover";
}

What is a Branch?

Branches are evaluated at runtime
Initial check: Correct tray selected?
Prevents printing errors

int selectedTray = 1;
if (selectedTray == 1) {
    cout << "Tray 1 selected";
} else if (selectedTray == 2) {
    cout << "Tray 2 selected";
} else {
    cout << "Invalid tray";
}

What is a Branch?

Branches check the state before action
Initial check: Printer ready to receive commands?
Ensures safe and correct execution

bool printerReady = true;
if (printerReady) {
    cout << "Ready for print job";
} else {
    cout << "Printer not ready";
}

Today, Tuesday Sept 9th

What is a branch? ✓
Decision-making in programs
Real-world example
if / else statements in C++
switch statements in C++
Homework and Lab

Decision-Making in Programs

Check if printer is jammed
Initial check prevents damage and wasted pages

bool printerJam = true;
if (printerJam) {
    cout << "Clear the jam first";
} else {
    cout << "Printer ready";
}

Decision-Making in Programs

Check if printer cover is closed
Initial check ensures safe operation

bool coverClosed = false;
if (coverClosed) {
    cout << "Printer ready";
} else {
    cout << "Close the cover";
}

Decision-Making in Programs

Check if selected tray matches print job
Initial check prevents printing errors

int selectedTray = 1;
if (selectedTray == 1) {
    cout << "Tray 1 selected";
} else if (selectedTray == 2) {
    cout << "Tray 2 selected";
} else {
    cout << "Invalid tray";
}

Decision-Making in Programs

Check if printer has paper loaded in multiple trays
Ensures correct tray is used

bool tray1Full = true;
bool tray2Full = false;
if (tray1Full) {
    cout << "Using tray 1";
} else if (tray2Full) {
    cout << "Using tray 2";
} else {
    cout << "No paper loaded";
}

Decision-Making in Programs

Check network connectivity for printing
Initial check prevents sending jobs to unavailable printer

bool networkConnected = true;
if (networkConnected) {
    cout << "Connected to printer";
} else {
    cout << "Cannot reach printer";
}

Decision-Making in Programs

Check if print queue has pending jobs
Initial check prevents empty job execution

bool queueEmpty = false;
if (!queueEmpty) {
    cout << "Processing jobs...";
} else {
    cout << "No jobs in queue";
}

Decision-Making in Programs

Check toner and paper together before batch job
Initial check prevents job failure

bool paperFull = true;
bool tonerOk = false;
if (paperFull && tonerOk) {
    cout << "Starting batch print";
} else {
    cout << "Check paper or toner";
}

Decision-Making in Programs

Decision-making ensures safe operations
Example: Printer ready for user commands

bool printerReady = true;
if (printerReady) {
    cout << "Ready for print job";
} else {
    cout << "Printer not ready";
}

Today, Tuesday Sept 9th

What is a branch? ✓
Decision-making in programs ✓
Real-world example
if / else statements in C++
switch statements in C++
Homework and Lab

Printer

Check paper tray before printing
Prevent errors if tray empty

bool paperTrayFull = true;
if (paperTrayFull) {
    cout << "Printing...";
} else {
    cout << "Add paper to tray";
}

Card Swipe Door

Check if card is valid
Grant or deny access

bool cardValid = false;
if (cardValid) {
    cout << "Door opens";
} else {
    cout << "Access denied";
}

Laundry Machine

Check if door is closed
Start washing only if safe

bool doorClosed = true;
if (doorClosed) {
    cout << "Starting wash cycle...";
} else {
    cout << "Close door first";
}

Smart Thermostat

Check current temperature
Turn heating/cooling on accordingly

int temp = 68;
if (temp < 70) {
    cout << "Heating ON";
} else if (temp > 75) {
    cout << "Cooling ON";
} else {
    cout << "System idle";
}

Traffic Light

Check light color
Decide whether to go, stop, or slow down

char light = 'Y';
if (light == 'G') {
    cout << "Go";
} else if (light == 'Y') {
    cout << "Slow down";
} else if (light == 'R') {
    cout << "Stop";
} else {
    cout << "Invalid signal";
}

Smart Fridge

Check if milk is expired
Alert user to replace it

bool milkExpired = true;
if (milkExpired) {
    cout << "Replace milk";
} else {
    cout << "Milk is good";
}

ATM Machine

Check if PIN is correct
Grant or deny access

bool pinCorrect = false;
if (pinCorrect) {
    cout << "Access granted";
} else {
    cout << "Incorrect PIN";
}

Elevator

Check requested floor
Move elevator accordingly

int requestedFloor = 5;
int currentFloor = 3;
if (requestedFloor > currentFloor) {
    cout << "Going up";
} else if (requestedFloor < currentFloor) {
    cout << "Going down";
} else {
    cout << "Already there";
}

Coffee Machine

Check water and bean levels
Start brewing only if sufficient

bool waterFull = true;
bool beansFull = false;
if (waterFull && beansFull) {
    cout << "Brewing coffee...";
} else {
    cout << "Refill water or beans";
}

Door Lock

Check if key or code is correct
Allow or deny entry

bool keyValid = true;
if (keyValid) {
    cout << "Door unlocked";
} else {
    cout << "Access denied";
}

Today, Tuesday Sept 9th

What is a branch? ✓
Decision-making in programs ✓
Real-world example ✓
if / else statements in C++
switch statements in C++
Homework and Lab

If / Else Statements

Basic conditional check
Syntax: if(condition) { ... } else { ... }
Use for two possible paths

int temp = 75;
if (temp > 70) {
    cout << "Turn on AC";
} else {
    cout << "AC off";
}

Else If

Handle multiple conditions in order
Evaluates first true condition
Useful for prioritized checks

int score = 82;
if (score >= 90) {
    cout << "A";
} else if (score >= 75) {
    cout << "B";
} else if (score >= 60) {
    cout << "C";
} else {
    cout << "Fail";
}

Best Practices

Keep conditions simple and readable
Use braces even for single statements
Avoid deeply nested ifs

if (isReady) {
    cout << "Ready";
} else {
    cout << "Not ready";
}

Common Mistakes

Using assignment instead of comparison (= vs ==)
Not handling else case
Multiple unrelated conditions in one if

bool active = true;
if (active = false) {  // ❌ mistake
    cout << "Inactive";
}

Interactive Question

Do you recommend if / else for multiple discrete values?

// Example: Decide printer mode
int mode = 2;
if (mode == 1) {
    cout << "Print B&W";
} else if (mode == 2) {
    cout << "Print Color";
} else {
    cout << "Unknown mode";
}

Nested If

Check multiple related conditions
Can become complex, reduce nesting if possible

bool hasPaper = true;
bool tonerOk = false;

if (hasPaper) {
    if (tonerOk) {
        cout << "Ready to print";
    } else {
        cout << "Replace toner";
    }
} else {
    cout << "Add paper";
}

Logical Operators

Combine multiple conditions with && or ||
Useful for if/else decision-making

bool paper = true;
bool toner = true;

if (paper && toner) {
    cout << "Printing...";
} else {
    cout << "Cannot print";
}

Short-circuit Evaluation

Conditions evaluated left-to-right
Stops as soon as outcome is known
Efficient for expensive checks

if (isConnected && hasJob) {
    cout << "Processing job";
}

Interactive Question

When should you prefer if/else over switch?

// Example: Printer toner check
int tonerLevel = 5;
if (tonerLevel < 3) {
    cout << "Refill toner";
} else if (tonerLevel <= 7) {
    cout << "Toner ok";
} else {
    cout << "Check sensor";
}

Summary – If / Else

Use for two or range-based conditions
Keep conditions readable
Use braces for clarity

bool ready = true;
if (ready) {
    cout << "Go";
} else {
    cout << "Wait";
}

Today, Tuesday Sept 9th

What is a branch? ✓
Decision-making in programs ✓
Real-world example ✓
if / else statements in C++ ✓
switch statements in C++
Homework and Lab

Switch Statement

Alternative to multiple else-if
Works with integers, chars, and enums
Check discrete values efficiently

int mode = 2;
switch(mode) {
    case 1: cout << "Print B&W"; break;
    case 2: cout << "Print Color"; break;
    default: cout << "Unknown mode";
}

Best Practices

Always use break after each case
Default case is optional but recommended
Keep cases simple and short

char option = 'B';
switch(option) {
    case 'A': cout << "Option A"; break;
    case 'B': cout << "Option B"; break;
    default: cout << "Invalid option";
}

Multiple Cases Same Action

Group multiple cases without code repetition

char grade = 'B';
switch(grade) {
    case 'A':
    case 'B': cout << "Pass"; break;
    case 'C': cout << "Consider"; break;
    default: cout << "Fail";
}

Switch with Enum

Better readability using enums

enum Mode { BW=1, COLOR=2 };
Mode m = COLOR;
switch(m) {
    case BW: cout << "B&W"; break;
    case COLOR: cout << "Color"; break;
}

Interactive Question

Do you recommend switch or if/else for checking a printer mode with 4 discrete options?

int printerMode = 3;
switch(printerMode) {
    case 1: cout << "B&W"; break;
    case 2: cout << "Color"; break;
    case 3: cout << "Draft"; break;
    case 4: cout << "High Quality"; break;
    default: cout << "Invalid mode";
}

Fallthrough Cases

Sometimes intentionally omit break
Can execute multiple cases sequentially

char c = 'A';
switch(c) {
    case 'A':
    case 'B': cout << "Good"; break;
    case 'C': cout << "Average"; break;
}

Default Case

Catches unexpected values
Prevents undefined behavior

int option = 5;
switch(option) {
    case 1: cout << "Option 1"; break;
    case 2: cout << "Option 2"; break;
    default: cout << "Unknown option";
}

Interactive Question

What happens if you forget break in a switch?

int x = 2;
switch(x) {
    case 1: cout << "One";
    case 2: cout << "Two"; // Falls through to next case
    case 3: cout << "Three";
}

Best Practices – Switch

Always include default
Keep cases simple
Use enums for readability

enum PrinterMode { BW=1, COLOR=2, DRAFT=3 };
PrinterMode mode = DRAFT;
switch(mode) {
    case BW: cout << "B&W"; break;
    case COLOR: cout << "Color"; break;
    case DRAFT: cout << "Draft"; break;
    default: cout << "Unknown";
}

Summary – Switch Statements

Use for discrete values
Readable and maintainable
Use default and breaks

char opt = 'C';
switch(opt) {
    case 'A': cout << "Option A"; break;
    case 'B': cout << "Option B"; break;
    case 'C': cout << "Option C"; break;
    default: cout << "Unknown";
}

Cyclomatic Complexity – Concept

Measures number of independent paths in a program
Helps assess code complexity
High complexity → harder to test and maintain

// Example concept
// A simple if/else has 2 paths
bool ready = true;
if (ready) {
    cout << "Go";
} else {
    cout << "Wait";
}

Cyclomatic Complexity – Formula

M = E – N + 2P
E = edges in flow graph
N = nodes in flow graph
P = connected components (usually 1 for single function)

// Simple function
int max(int a, int b) {
    if (a > b) return a;
    else return b;
}

Practical Example – Printer Check

Check paper, toner, and connection
3 conditions → cyclomatic complexity = 4

bool paper = true;
bool toner = true;
bool connected = true;

if (paper && toner && connected) {
    cout << "Ready to print";
} else {
    cout << "Cannot print";
}

Interactive Question

Which has higher cyclomatic complexity?
A simple if/else or nested ifs checking 3 conditions separately?

// Nested example
if (paper) {
    if (toner) {
        if (connected) {
            cout << "Ready";
        }
    }
}

Best Practices

Keep cyclomatic complexity low (≤10 per function)
Refactor complex functions into smaller ones
Use switch statements or boolean logic to simplify

// Refactor example
bool readyToPrint(bool paper, bool toner) {
    return paper && toner;
}

Today, Tuesday Sept 9th

What is a branch? ✓
Decision-making in programs ✓
Real-world example ✓
if / else statements in C++ ✓
switch statements in C++ ✓
Homework and Lab

Introduce Horse Race Game
Track has 3 positions
Player controls horse moves
Game ends at finish line


// Overview: Start -> Middle -> Finish
// Player chooses moves

Horse starts at Start
Player chooses actions: Move or Quit
Each move is a decision branch


// Rules:
// Positions: START = 0, MIDDLE = 1, FINISH = 2
// Player input determines horse move

Define constants for positions
Avoid magic numbers


const int START = 0;
const int MIDDLE = 1;
const int FINISH = 2;

Use variables to store state
horsePos tracks position
choice stores player input


int horsePos = START;
int choice;

Print welcome message
Tell player rules
Show initial horse position


cout << "Horse Race Game!" << endl;
cout << "Horse starts at the beginning." << endl;
cout << "Horse: H _ _" << endl;

Ask player for first action
1 = Move Forward, 2 = Quit


cout << "Choose: 1=Move, 2=Quit" << endl;
cin >> choice;

Check choice with if / else
Move horse if 1, quit if 2


if (choice == 1) {
    horsePos = MIDDLE;
    cout << "Horse moved to the middle!" << endl;
    cout << "Horse: _ H _" << endl;
} else {
    cout << "You quit the race." << endl;
    return 0;
}

Q: What does horsePos store?
A: Current position of the horse


// horsePos = START / MIDDLE / FINISH

Ask player for second action
1 = Move Forward, 2 = Quit


cout << "Choose: 1=Move, 2=Quit" << endl;
cin >> choice;

Use switch-case for decision
Case 1 → Finish, Case 2 → Quit


switch(choice) {
    case 1:
        horsePos = FINISH;
        cout << "Horse: _ _ H" << endl;
        cout << "You reached finish line!" << endl;
        break;
    case 2:
        cout << "You quit the race." << endl;
        break;
    default:
        cout << "Invalid input." << endl;
}

Check if horse reached finish
Display winning message


if (horsePos == FINISH) {
    cout << "Congratulations! You won!" << endl;
}

Player chooses to quit
Game ends immediately
Show quit message


else {
    cout << "You quit the race. Game over." << endl;
}

Q: Why use switch-case?
A: Easier to handle multiple options


// switch(choice) { case 1: ... case 2: ... }

Visual representation of horse moves
Start → Middle → Finish


// Start: H _ _
// Middle: _ H _
// Finish: _ _ H

Player chose Move Forward
Horse updated to Middle


horsePos = MIDDLE;
cout << "Horse: _ H _" << endl;

Player chose Move Forward
Horse reached Finish
Display winning message


horsePos = FINISH;
cout << "Horse: _ _ H" << endl;
cout << "🏆 You won the race!" << endl;

Player can quit at first or second choice
Game ends immediately


if(choice == 2) {
    cout << "You quit the race. Game over." << endl;
}

Flow diagram of decisions
First: Move or Quit
Second: Move or Quit


// Pseudocode
// choice1 -> if/else -> horsePos = MIDDLE
// choice2 -> switch -> horsePos = FINISH / Quit

Use assignments to update horsePos
e.g., horsePos = MIDDLE


horsePos = MIDDLE;  // updates horse position

Constants used to label positions
START = 0, MIDDLE = 1, FINISH = 2


const int START = 0;
const int MIDDLE = 1;
const int FINISH = 2;

Today, Tuesday Sept 16th

Introduction to Loops
Why Loops are Useful
while Loop in C++
for Loop in C++
Real-world Loop Examples
Homework and Lab

Introduction to Loops

Loops repeat a block of code
Used to avoid writing repetitive code
Types in C++: for, while, do-while
Can also nest loops for complex tasks

For Loop

Use when number of iterations is known
Syntax: for(init; condition; update)
Common for counting and arrays

for (int i = 1; i <= 5; i++) {
    cout << "Count: " << i << endl;
}

While Loop

Use when iterations depend on condition
Condition checked before each loop
Runs 0 or more times

int x = 1;
while (x <= 5) {
    cout << "x = " << x << endl;
    x++;
}

Do-While Loop

Always executes at least once
Condition checked after each loop
Good for menus and input validation

int choice;
do {
    cout << "1=Play, 2=Quit" << endl;
    cin >> choice;
} while (choice != 2);

Nested Loops

Loop inside another loop
Useful for grids, tables, patterns


for (int r = 1; r <= 3; r++) {
    for (int c = 1; c <= 3; c++) {
        cout << "(" << r << "," << c << ")";
    }
    cout << endl;
}

Break and Continue

break → exits loop early
continue → skips to next iteration

for (int i = 1; i <= 5; i++) {
    if (i == 3) continue; // skip 3
    if (i == 5) break;    // stop at 5
    cout << i << " ";
}

Common Mistakes

Forgetting loop update → infinite loop
Off-by-one errors (≤ vs <)
Using wrong condition

// Infinite loop: forgot i++
for (int i = 0; i < 5; ) {
    cout << i << " ";
}

// Off-by-one error
for (int i = 0; i <= 5; i++) {
    cout << i << " "; // Prints 0–5 instead of 0–4
}

Which loop guarantees at least one execution?

for loop
while loop
do-while loop
nested loop

What will be the value of x?

int x = 0;
for (int i = 1; i <= 5; i++) {
    x = x + i;
}

What will be the value of y?

int y = 1;
int i = 1;
while (i <= 4) {
    y = y * 2;
    i = i + 1;
}

What will be the value of count?

int count = 0;
for (int i = 10; i > 0; i -= 2) {
    count = count + 1;
}

What will be the value of z?

int z = 100;
do {
    z = z - 20;
} while (z > 50);

What will be the value of sum?

int sum = 0;
for (int i = 1; i <= 3; i++) {
    for (int j = 1; j <= 2; j++) {
        sum = sum + 1;
    }
}

Chessboard with Loops

We can draw an 8×8 chessboard using nested loops
No array is needed: just alternate characters
Use row + column sum to decide black or white square

// Print an 8x8 chessboard
for (int row = 0; row < 8; row++) {
    for (int col = 0; col < 8; col++) {
        if ((row + col) % 2 == 0)
            cout << "W "; // White square
        else
            cout << "B "; // Black square
    }
    cout << endl;
}

W B W B W B W B
B W B W B W B W
W B W B W B W B
B W B W B W B W
W B W B W B W B
B W B W B W B W
W B W B W B W B
B W B W B W B W

Today, Tuesday Sept 23rd

Introduction to Arrays
Array Declaration and Initialization
Accessing, Updating Array Elements
Introduction to Vectors in C++
Comparing Arrays vs Vectors
Practical Examples and Use Cases
Homework and Lab

Why Do We Need Arrays?

Store multiple values, one name
Avoid creating many variables
Better organize, process data
Foundation for adv. data structures

Before Arrays

Each flower stored in its own variable
Becomes messy with many flowers
Hard to loop through and manage


#include <iostream>
#include <string>
using namespace std;

int main() {
    string flower1 = "Rose";
    string flower2 = "Tulip";
    string flower3 = "Lily";

    cout << flower1 << endl;
    cout << flower2 << endl;
    cout << flower3 << endl;
}

After Arrays

Store multiple flowers under one name
Access any element using an index
Easy to loop through flowers


#include <iostream>
#include <string>
using namespace std;

int main() {
    string flowers[3] = {"Rose", "Tulip", "Lily"};
    cout << flowers[0]; // Rose
}

Accessing Array Elements

Use index to read or update values
flowers[0] gives "Rose"
flowers[1] = "Orchid" update 2nd elem


flowers[1] = "Orchid";
cout << flowers[1]; // Orchid

What will this code output?


string flowers[3] = {"Rose", "Tulip", "Lily"};
cout << flowers[2];

Rose
Tulip
Lily
Orchid

Iterating Over Flower Arrays

Use a loop to access all flowers
for loop runs from 0 to array size-1
Useful for displaying inventory


for(int i = 0; i < 3; i++) {
    cout << flowers[i] << endl;
}

Flower Prices in Arrays

Use numeric arrays for prices
Keep index aligned with flower names
flowers[0] = Rose → prices[0] = 2.99


string flowers[3] = {"Rose", "Tulip", "Lily"};
double prices[3] = {2.99, 1.99, 3.49};

cout << flowers[0] 
     << " costs $" 
     << prices[0];

Multidimensional Flower Arrays

Use 2D arrays to store quantities by day
rows = flowers, columns = days
Example: flower sales per week


int sales[2][3] = {
   {10, 15, 12}, // Roses
   { 8, 11,  9}  // Tulips
};

cout << sales[0][1]; // 15

Size of Flower Arrays

Size is fixed at compile time
Use sizeof to calculate element count
Divide total size by element size


int sizes[4] = {5, 6, 7, 8};
int count = sizeof(sizes) / sizeof(sizes[0]);
cout << "Total flowers: " << count;

Updating Flower Inventory

Arrays allow element reassignment
Replace old values with new ones
Example: Roses sold out → inventory 0


int inventory[3] = {20, 15, 10};
inventory[0] = 0; 
cout << inventory[0]; // 0

What is the output of this code?


string flowers[3] = {"Rose", "Tulip", "Lily"};
flowers[2] = "Daisy";
cout << flowers[2];

Rose
Tulip
Lily
Daisy

Arrays and Parallel Data

Keep multiple arrays in sync
flowers[i] ↔ prices[i] ↔ inventory[i]
Helps model flower shop data


string flowers[2] = {"Rose", "Tulip"};
double prices[2] = {2.99, 1.99};
int stock[2] = {12, 18};

cout << flowers[1] << " costs $"
     << prices[1] << " with "
     << stock[1] << " in stock.";

Passing Arrays to Functions

Pass array name as argument
Size must be handled separately
Useful for reusable flower shop utilities


void printFlowers(string arr[], int size) {
    for(int i=0; i<size; i++) {
        cout << arr[i] << endl;
    }
}

string flowers[3] = {"Rose","Tulip","Lily"};
printFlowers(flowers, 3);

Which statement about arrays in C++ is TRUE?

Arrays automatically resize when new items are added
Arrays store mixed data types
Arrays have a fixed size once declared
Arrays start indexing from 1

Simple Flower Tic-Tac-Toe

Array stores 3 cells
Players place X or O
Demonstrates updating array elements


int main() {
    char board[3] = {'_', '_', '_'};

    board[0] = 'X'; // Player 1
    board[1] = 'O'; // Player 2
    board[2] = 'X'; // Player 1

    for(int i=0; i<3; i++) {
        cout << board[i] << " ";
    }
    // Output: X O X
}

Introduction to Vectors

Dynamic arrays in C++
Size can grow or shrink
Useful for flower shop inventory


#include <vector>
#include <string>
using namespace std;

vector<string> flowers;

Adding Flowers to a Vector

Use push_back() to insert elements
No need to declare fixed size
More flexible than arrays


vector<string> flowers;
flowers.push_back("Rose");
flowers.push_back("Tulip");
flowers.push_back("Lily");

Which method adds a new flower to the end of a vector?

flowers.add()
flowers.insert()
flowers.push_back()
flowers.append()

Accessing Vector Elements

Use index like arrays
Index starts from 0
flowers[0] = first flower


cout << flowers[0]; // Rose
flowers[1] = "Orchid";

Looping Over Vectors

Use for loop to print all flowers
Use flowers.size() to get count
Dynamic: adjusts when vector grows


for(int i=0; i<flowers.size(); i++) {
    cout << flowers[i] << endl;
}

Which function returns the number of elements in a vector?

flowers.length()
flowers.size()
flowers.count()
flowers.elements()

Removing Flowers from a Vector

Use pop_back() to remove last element
Vector size decreases automatically
No need to manage manually


flowers.pop_back(); // removes "Lily"

Flower Prices with Vectors

Use parallel vectors
flowers[i] ↔ prices[i]
Dynamic sizes stay consistent


vector<string> flowers = {"Rose", "Tulip"};
vector<double> prices = {2.99, 1.99};

cout << flowers[0] 
     << " costs $" 
     << prices[0];

What happens if you call pop_back() on a vector?

Removes first element
Removes last element
Deletes the whole vector
Adds a default value

Vector of Quantities

Track stock for each flower
Update easily as sales happen
No need to re-declare array size


vector<int> stock = {12, 8, 15};
stock[1] = 10; // update Tulip stock

Iterating with Range-based For

C++11 feature
Simpler syntax for looping
Great for flower display


for(string f : flowers) {
    cout << f << endl;
}

Which loop style automatically iterates through all vector elements?

while loop
range-based for loop
do-while loop
traditional for loop

When to Use Arrays vs Vectors?

...with fixed number of flowers?
...when flowers are added/removed?
...if flowers never change?


// Example: Array (fixed size)
string flowers[3] = {"Rose", "Tulip", "Lily"};

// Example: Vector (dynamic size)
vector<string> flowers = {"Rose", "Tulip"};
flowers.push_back("Lily");

Exercise: CountValues in Array

Write a function that takes an array of integers (or flower quantities)
Return the total sum of all elements
Example: [5, 3, 2] → total = 10
Test with different arrays of flower counts

Exercise: Create 8×8 Chess Board

Create a 2D array (8 rows × 8 columns)
Each cell can hold a chess piece
Symbols: 'K' for King, 'Q' for Queen
Initialize board with standard setup
Print the board in a readable format

Arrays vs Vectors Comparison

Feature	Array	Vector
Size	Fixed at compile time	Dynamic, can grow or shrink
Declaration	int quantities[5];	vector<int> quantities;
Adding elements	Cannot add beyond declared size	Use `push_back()` to add elements
Removing elements	Not possible	Use `pop_back()` to remove last element
Memory	Contiguous memory, static	Contiguous memory, resizes dynamically
Access	Use index: `quantities[0]`	Use index: `quantities[0]`
Use case example	Flower types fixed: 3 types	Inventory can grow: add new flower types

Applications Using Variables, Conditions, Loops, and Arrays

Simple calculators and math operations
Inventory management systems
Basic games (e.g., Tic-Tac-Toe, number guessing)
Data processing and reporting (sum, average, min/max)
Simulations (traffic lights, queues, counters)
Text or number-based pattern printing

Today, Tuesday Sept 25

Variables and Data Types
Conditions
Loops
Arrays
Vectors (optional)
Combine all concepts in a complete program: Tic-Tac-Toe
Homework and Lab: extend the game

Step 1: Variables

Store board, current player, and game state
Example:

char board[3][3]; 
char currentPlayer = 'X'; 
bool gameOver = false;

Step 2: Conditions

Check if a move is valid
Check for a win or draw
Switch players

if (board[row][col] == ' ') {
    board[row][col] = currentPlayer;
} else {
    cout << "Invalid move!";
}
if (checkWin(board, currentPlayer)) gameOver = true;

Step 3: Loops

Main game loop
Keep the game running until gameOver is true

while (!gameOver) {
    printBoard(board);
    getPlayerMove();
    updateBoard();
    checkWinOrDraw();
    switchPlayer();
}

Step 4: Arrays

Use a 2D array to store the 3x3 board
Access and update elements using indices

board[0][0] = 'X';
char cell = board[1][2];

Step 5: Vectors (Optional)

Track move history dynamically
Example:

#include <vector>
vector<pair<int,int>> moves;
moves.push_back(make_pair(row, col));

Step 6: Helper Function - Print Board

void printBoard(char board[3][3]) {
    for (int i=0; i<3; i++) {
        for (int j=0; j<3; j++) {
            cout << board[i][j] << ' ';
        }
        cout << endl;
    }
}

Step 7: Helper Function - Check Win

bool checkWin(char board[3][3], char player) {
    // check rows, columns, diagonals
    for (int i=0; i<3; i++) {
        if (board[i][0]==player && board[i][1]==player && board[i][2]==player) return true;
        if (board[0][i]==player && board[1][i]==player && board[2][i]==player) return true;
    }
    if (board[0][0]==player && board[1][1]==player && board[2][2]==player) return true;
    if (board[0][2]==player && board[1][1]==player && board[2][0]==player) return true;
    return false;
}

Step 8: Full Game Loop

while (!gameOver) {
    printBoard(board);
    int row, col;
    cout << "Enter row and column: ";
    cin >> row >> col;
    if (board[row][col]==' ') {
        board[row][col] = currentPlayer;
        if (checkWin(board, currentPlayer)) {
            cout << currentPlayer << " wins!\n";
            gameOver = true;
        } else {
            switchPlayer();
        }
    } else {
        cout << "Invalid move!\n";
    }
}

Homework / Lab

Add move history using vectors
Implement undo functionality
Add a scoring system or play-again option

Today, Tuesday Sept 30th

What is a Function?
Function Declaration & Definition
Function Call & Parameters
Return Values and Void Functions
Function Overloading & Default Params
Inline and Recursive Functions
Pass by Value & Reference
Const Parameters & Func Templates
Static Functions & Func Pointers
Recap and Practice Questions

What is a Function?

Functions are reusable blocks of code
They perform specific tasks
Helps in modular programming
Example: Calculate sum of two numbers

// Function declaration
int sum(int a, int b);

Function Signature in C++

Defines function name and parameter types
Determines how function is called
Includes return type, name, and parameters
Does NOT include the function body
Used by compiler to differentiate functions

// Example function signatures
int add(int a, int b);
void displayScore(int score);
double calculateAverage(double total, int count);

Function Declaration & Definition

Declaration tells the compiler about function
Definition provides the actual code
Declaration: int sum(int, int);
Definition: int sum(int a,int b){return a+b;}

int sum(int a, int b) {
    return a + b;
}

Function Call

Functions are called to execute code
Arguments passed to function parameters
Example: Call sum(5, 3)

int result = sum(5, 3);
cout << result; // Outputs 8

Function Parameters

Parameters allow data input to function
Can have multiple parameters
Supports pass by value and pass by reference

void greet(string name) {
    cout << "Hello, " << name;
}

Return Values

Functions can return data to the caller
Use the return keyword
Return type must match declaration

int square(int x) {
    return x * x;
}

Void Functions

Void functions do not return a value
Used for performing actions only
Example: Printing a message

void printHello() {
    cout << "Hello World";
}

Function Overloading

Same function name, different parameters
Compiler differentiates by signature
Improves code readability

int sum(int a,int b);
double sum(double x,double y);

Default Parameters

Functions can have default values
Caller may omit those arguments
Defaults defined in declaration

int add(int a, int b=5) {
    return a+b;
}

Inline Functions

Inline suggests compiler replace call with code
Reduces function call overhead
Good for small functions

inline int cube(int x) {
    return x*x*x;
}

Recursion

Function calls itself
Must have a base case to stop recursion
Example: Factorial calculation

int fact(int n) {
    if(n<=1) return 1;
    return n*fact(n-1);
}

Pass by Value

Function gets a copy of the argument
Changes inside function do not affect caller

void update(int x) {
    x = x+5;
}

Pass by Reference

Function gets reference to original variable
Changes affect the caller variable

void update(int &x) {
    x = x+5;
}

Const Parameters

Prevents function from modifying argument
Useful for passing large objects safely

void display(const string &s) {
    cout << s;
}

Function Templates

Templates allow generic functions
Works with multiple data types
Reduces code duplication

template
T add(T a,T b){return a+b;}

Static Functions

Function scope limited to file
Cannot be called from other files

static void helper() {
    cout << "Helper function";
}

Function Pointers

Pointer that stores function address
Allows dynamic call of functions

int (*fp)(int,int) = sum;
cout << fp(2,3);

Recap: Function Types

Void and non-void functions
Inline, recursive, overloaded
Template and static functions

// Examples of all function types
void f1();
int f2(int x);
inline int f3(int y);

Question 1

Which function type returns no value?
A) void B) inline C) static D) template

// Answer: void

Question 2

Pass by reference allows function to modify caller?
A) Yes B) No

// Answer: Yes

Question 3

Template functions allow which of the following?
A) Only int B) Multiple types C) Only void

// Answer: B) Multiple types

Practice: Write Game Functions

Write function to calculate player score
Write function to display health status
Write function to check if player won
Use parameters for player stats
Return appropriate values from function

#include <iostream>
using namespace std;

// Example function skeletons
int calculateScore(int kills, int coins);
void displayHealth(int health);
bool hasWon(int score);

int main() {
    // Call your functions here
}

Today, Thursday Oct 2nd

Practice: Build a 10-Function Game (parallel work)

10-Function Game: Parallel Work

Student 1 → printWelcome()
Student 2 → generateSecret(int min, int max)
Student 3 → getPlayerGuess()
Student 4 → checkGuess(int secret, int guess)
Student 5 → printHint(int secret, int guess)
Student 6 → printResult(bool isCorrect)
Student 7 → askPlayAgain()
Student 8 → printGoodbye()
Student 9 → printScore(int score)
Student 10 → updateScore(int score, bool correct)
Everyone → main()

Required Libraries for the Game
<iostream> → input/output
<cstdlib> → random numbers
<ctime> → seed random
using namespace std; → avoid std::


#include <iostream>
#include <cstdlib>   // for rand() and srand()
#include <ctime>     // for time()
using namespace std;

Function 1: printWelcome() → Print a welcome message

void printWelcome() {
    cout << "Welcome!" << endl;
    cout << "Number Guessing Adventure!" << endl;
}

Function 2: generateSecret() → Generate a random number between min and max

int generateSecret(int min, int max) {
    return rand() % (max - min + 1) + min;
}

Function 3: getPlayerGuess() → Ask the player for a guess

int getPlayerGuess() {
    int guess;
    cout << "Enter your guess: ";
    cin >> guess;
    return guess;
}

Function 4: checkGuess() → Compare guess with secret

bool checkGuess(int secret, int guess) {
    return guess == secret;
}

Function 5: printHint() → Print if guess is too high or too low

void printHint(int secret, int guess) {
    if (guess < secret) cout << "Too low!";
    else if (guess > secret) cout << "Too high!";
}

Function 6: printResult() → Print if guess is correct

void printResult(bool isCorrect) {
    if (isCorrect) cout << "Correct! You guessed it!";
}

Function 7: askPlayAgain() → Ask if player wants to play again

bool askPlayAgain() {
    char choice;
    cout << "Play again? (y/n): ";
    cin >> choice;
    return choice == 'y' || choice == 'Y';
}

Function 8: printGoodbye() → Print a goodbye message

void printGoodbye() {
    cout << "Thanks for playing! Goodbye!" << endl;
}

Function 9: printScore() → Print player's current score

void printScore(int score) {
    cout << "Your current score: " << score << endl;
}

Function 10: updateScore() → Update score if guess is correct

int updateScore(int score, bool correct) {
    if (correct) return score + 1;
    return score;
}

Function 11: main() → Connect all functions to run the game


int main() {
    srand(time(0));
    int score = 0;
    printWelcome();
    bool playing = true;

    while (playing) {
        int secret = generateSecret(1, 100);
        bool correct = false;

        while (!correct) {
            int guess = getPlayerGuess();
            correct = checkGuess(secret, guess);
            printHint(secret, guess);
            score = updateScore(score, correct);
        }

        printResult(correct);
        printScore(score);
        playing = askPlayAgain();
    }

    printGoodbye();
    return 0;
}

Today, Tuesday Oct 7th

Object-Oriented Programming (OOP)
Classes and Objects
Midterm Review & Sample Questions

The Formula of an Object

Variables + Functions = Object

Data (attributes) + Behavior (methods) = Object

Example: Car = (model, year) + (start(), stop())

What is OOP?

Program based on real-world entities
Objects combine data and actions
Improves organization and reuse
Example: Think of a Car as an object

Why Use OOP?

Models real-world systems easily
Makes code modular and readable
Encourages reuse through objects
Reduces redundancy

OOP in the Real World

Car has properties (model, color)
It has actions (start, stop)
Each car unique but same design

What is a Class?

A blueprint for creating objects
Defines attributes and behaviors
Does not store data itself
Example: “Car” is a class


class Car {
public:
    string model;
    int year;
    void start() {
        cout << "Car started";
    }
};

What is an Object?

An instance of a class
Has its own values for attributes
Can use class methods
Example: myCar is an object of Car


Car myCar;
myCar.model = "Tesla";
myCar.year = 2024;
myCar.start();

Creating Multiple Objects

Each object has its own data
Objects can share class structure
Memory allocated separately


Car car1, car2;
car1.model = "Honda";
car2.model = "BMW";

Data and Behavior

Data (attributes): model, color, year
Behavior (methods): start(), stop()
Together form an object’s identity

Recap: Class and Object

Class: Blueprint for a car
Object: A specific car created from blueprint
OOP helps model real-world systems easily

Practice Question

Create a Car class with attributes: brand, year
Add a method displayInfo() to print details
Create two Car objects and call the method


Car car1, car2;
car1.brand = "Toyota";
car2.brand = "Ford";
car1.displayInfo();
car2.displayInfo();

Today, Tuesday Oct 21th

Midterm Review
Object-Oriented Programming (OOP)
Classes and Objects

Today, Thursday Oct 23th

Brief Quiz and Midterm Survey
Object-Oriented Programming (cont.)
Lab, Homework, and Project

Midterm Survey

More labs/quiz (in class)
Review Functions and Arrays
Attendance
Less random asking

Brief Quiz

Not graded
Previous topics
Concept and Coding
On paper

Today, Thursday Oct 23th

Brief Quiz and Midterm Survey ✓
Object-Oriented Programming (cont.)
Lab, Homework, and Project

Object-Oriented Programming

Model real-world entities
Encapsulate data and behavior
Promotes reusability

Why model entities in OOP?


<!-- Example: Vehicles and Cars -->

Inheritance Example: Car

Car "is-a" Vehicle
Reuse brand and honk() methods

Concept: Inheritance


+-----------+         +-----------+
| Vehicle   | <----   | Car       |
+-----------+         +-----------+
| brand     |         | doors     |
| honk()    |         | honk()    |
+-----------+         +-----------+

Composition Example: Car

Car "has-a" Engine

Concept: Composition


+-----------+         +-----------+
| Car       | <----   | Engine    |
+-----------+         +-----------+
| brand     |         | hp        |
| doors     |         +-----------+
| engine    |  // Car "has-a" Engine
+-----------+

Inheritance Example: Agriculture

Tractor "is-a" FarmEquipment

Concept: Inheritance


+----------------+       +----------------+
| FarmEquipment  | <--   | Tractor        |
+----------------+       +----------------+
| manufacturer   |       | horsepower     |
| start()        |       | start()        |
+----------------+       +----------------+

Composition Example: Agriculture

Tractor "has-a" Plow

Concept: Composition


+-------------+         +------------+
| Tractor     | <-----  | Plow       |
+-------------+         +------------+
| manufacturer|         | type       |
| engine      |         +------------+
| plow        | // Tractor "has-a" Plow
+-------------+

Inheritance Example: Healthcare

MRI "is-a" MedicalDevice

Concept: Inheritance


+----------------+       +----------------+
| MedicalDevice  | <--   | MRI            |
+----------------+       +----------------+
| model          |       | resolution     |
| operate()      |       | operate()      |
+----------------+       +----------------+

Composition Example: Healthcare

MRI "has-a" CoolingSystem

Concept: Composition


+----------------+       +----------------+
| MRI            | <--   | CoolingSystem  |
+----------------+       +----------------+
| model          |       | capacity       |
| power          |       +----------------+
| coolingSystem  | // MRI "has-a" CoolingSystem
+----------------+

Defining a Class

Keyword <code>class</code>
Members: data + functions


class Vehicle {
public:
    string brand;
    void honk() {
        cout << "Beep!" << endl;
    }
};

Creating Objects

Objects are instances of classes

How do we instantiate Vehicle?


Vehicle v1;
v1.brand = "Toyota";
v1.honk();

Encapsulation

Hide details using access specifiers
public, private, protected


class Vehicle {
private:
    int speed;
public:
    void setSpeed(int s){ speed = s; }
    int getSpeed(){ return speed; }
};

Constructors

Initialize objects automatically

Why use constructors?


class Vehicle {
public:
    string brand;
    Vehicle(string b){ brand = b; }
};

Using Constructors

Called when object is created


Vehicle v1("Honda");
cout << v1.brand;

Destructors

Clean up resources

When is a destructor called?


~Vehicle() {
    cout << brand << " destroyed." << endl;
}

Inheritance

Derive new class from existing one
Reuse attributes & methods


class Car : public Vehicle {
public:
    int doors;
};

Derived Class Access

Inherited members become available

How do Car objects access Vehicle members?


Car c1;
c1.brand = "Ford";
c1.honk();
c1.doors = 4;

Protected Members

Accessible in derived classes


class Vehicle {
protected:
    int year;
};

Base Constructor Calls

Use initializer list

How does Car call Vehicle constructor?


class Car : public Vehicle {
public:
    Car(string b, int y) : Vehicle(b) {
        year = y;
    }
};

Multi-Level Inheritance

Derived class can be extended further


class ElectricCar : public Car {
public:
  int batteryCapacity;
  ElectricCar(string b,int y,int d,int bc) : Car(b,y,d){
    batteryCapacity = bc;
  }
};

Accessing Members

ElectricCar has all Car and Vehicle members

How do we set all attributes for ElectricCar?


ElectricCar e1("Tesla",2025,4,75);
cout << e1.brand << ", ";
cout << e1.doors << ", ";
cout << e1.batteryCapacity << endl;

Overriding Functions

Derived class modifies base behavior


class Car : public Vehicle {
public:
    void honk() {
        cout << "Car horn!" << endl;
    }
};

Abstract Classes

Contains pure virtual functions

Why use abstract classes?


class Vehicle {
public:
    virtual void honk() = 0;
};

Implementing Abstract Methods

Derived class must override pure virtual functions


class Car : public Vehicle {
public:
    void honk() override {
        cout << "Car horn!" << endl;
    }
};

Composition vs Inheritance

“Has-a” vs “Is-a” relationship

Question: How does Car “have” an Engine?


class Engine {
public: int hp;
};
class Car {
    Engine e; // Composition
};

Static Members

Shared among all objects


class Car {
public:
    static int count;
};
int Car::count = 0;

Using Static Members

Access without creating objects

How to increment static counter?


Car::count++;
cout << Car::count;

Namespaces

Organize code more...


namespace vehicles {
    class Car {};
}
vehicles::Car c1;

Multiple Inheritance

A class can inherit from multiple bases

How does SmartCar inherit GPS and MusicSystem?


class GPS {};
class MusicSystem {};
class SmartCar : public GPS, public MusicSystem {};
SmartCar s;

Summary

Classes encapsulate data
Inheritance builds hierarchies
Polymorphism enables flexibility


<!-- Vehicle → Car → ElectricCar -->

Today, Tuesday Oct 28th

Introduction to Data Streams
Saving Data Streams to File in C++
Examples and Exercises


// Topic: Saving Data Streams to File
// Language: C++

What is a Data Stream?

A continuous flow of data elements.
Streams can be input (read) or output (write).
Used in sensors, logging, and files.


// Streams in C++ represent data flow:
// input  -> istream
// output -> ostream

C++ Stream Classes

istream: for reading data
ostream: for writing data
fstream: for both


#include <iostream>
#include <fstream>
using namespace std;

File Stream Objects

ifstream - input from file
ofstream - output to file
fstream - both directions


ifstream inFile;
ofstream outFile;
fstream file;

Opening a File for Writing

Use ofstream with filename
Automatically creates file if missing
Overwrites existing file by default


ofstream outFile("data.txt");
outFile << "Hello, stream!" << endl;
outFile.close();

Opening Modes

ios::out - Write mode
ios::in - Read mode
ios::app - Append mode
ios::binary - Binary mode


ofstream file("log.txt", ios::app);
file << "New entry\n";
file.close();

Reading from a File

Use ifstream to read files
Use getline() to read line-by-line


ifstream inFile("data.txt");
string line;
while (getline(inFile, line)) {
    cout << line << endl;
}
inFile.close();

Error Checking

Always verify that file opened successfully
Use is_open() or fail()


ofstream out("output.txt");
if (!out.is_open()) {
    cerr << "Error opening file\n";
}

Stream States

good() – No errors
eof() – End of file reached
fail() – Logical error
bad() – Read/write error


if (in.fail()) {
    cout << "Read failed!" << endl;
}

Flushing the Stream

flush() forces buffer write
Useful for real-time logs


outFile << "Saving..." << flush;

Binary Output Streams

Use ios::binary mode
Write raw bytes using write()


ofstream out("sensor.bin", ios::binary);
float value = 24.5;
out.write((char*)&value, sizeof(value));
out.close();

Binary Input Streams

Read binary data using read()
Cast to the correct data type


ifstream in("sensor.bin", ios::binary);
float value;
in.read((char*)&value, sizeof(value));
in.close();

Appending Data

Open with ios::app
Writes at end of file


ofstream file("log.txt", ios::app);
file << "New session started\n";
file.close();

Redirecting cout to File

Capture console output to file
Use rdbuf() to redirect


ofstream log("out.txt");
streambuf *old = cout.rdbuf(log.rdbuf());
cout << "Logging data...";
cout.rdbuf(old);

Continuous Data Stream Example

Simulate sensor readings
Write multiple values in a loop


ofstream data("stream.txt");
for (int i = 0; i < 5; ++i)
    data << "Reading " << i << endl;
data.close();

Reading Until EOF

Loop until eof() is true
Useful for unknown file lengths


while (!in.eof()) {
    getline(in, line);
    cout << line << endl;
}

Error Recovery

Use clear() to reset stream state
Then retry operation if needed


if (in.fail()) {
    in.clear();
    in.seekg(0);
}

Practical Use Case

Store sensor readings over time
Save to CSV or binary file
Later load for analysis


ofstream log("sensor.csv");
log << "time,temp\n";
for (int i=0;i<10;i++)
  log << i << "," << 20+i << endl;
log.close();

Summary

Streams simplify file I/O
Use text or binary modes as needed
Always close and check for errors


// Save, Read, Verify
// C++ file streams = reliable data persistence

Today, Tuesday Oct 30th

Introduction to Data Streams
Saving Data Streams to File in C++
Examples and Exercises

Slide: C++ Stream Class Hierarchy

Shows inheritance from ios base class
Separation of input (istream) and output (ostream)
Specialized classes for files and combined streams

Class	Type	Description
ios	Base	Base class for all stream operations
ostream	Output	Provides output operations (<<)< /td>
istream	Input	Provides input operations (>>)
ofstream	Output File	Write to files
ifstream	Input File	Read from files
iostream	Input/Output	Supports both reading and writing
fstream	File I/O	Read and write files

Introduction to Streams

What is a stream?
Input vs Output streams
Standard streams: cin, cout, cerr


// Input and output streams
#include 
using namespace std;

int main() {
    int x;
    cout << "Enter a number: ";
    cin >> x;
    cout << "You entered: " << x << endl;
    return 0;
}

File Streams

ofstream: write to file
ifstream: read from file
fstream: read/write


#include 
using namespace std;

ofstream outFile("data.txt");
outFile << "Hello, file!" << endl;
outFile.close();

Opening Files

Open in text mode
Open in binary mode
Check if open succeeded


#include 
#include 
using namespace std;

ifstream inFile("data.txt");
if(!inFile) {
    cerr << "Error opening file!" << endl;
}

Writing to a File

Use << operator
Write strings or numbers
Close after writing


ofstream outFile("output.txt");
outFile << "C++ streams are easy!" << endl;
outFile << 42 << endl;
outFile.close();

Reading from a File

Use >> operator or getline
Read strings or numbers
Check for EOF


ifstream inFile("output.txt");
string line;
while(getline(inFile, line)) {
    cout << line << endl;
}
inFile.close();

Stream States

good(), eof(), fail(), bad()
Check before read/write
Recover from errors


ifstream inFile("data.txt");
if(inFile.good()) {
    cout << "Ready to read." << endl;
}
if(inFile.eof()) {
    cout << "End of file reached." << endl;
}

Binary Files

Use ios::binary
Store data efficiently
Read/write raw bytes


ofstream outFile("data.bin", ios::binary);
int x = 12345;
outFile.write(reinterpret_cast(&x), sizeof(x));
outFile.close();

Reading Binary Files

Read using read()
Use reinterpret_cast
Know data type size


ifstream inFile("data.bin", ios::binary);
int x;
inFile.read(reinterpret_cast(&x), sizeof(x));
cout << x << endl;
inFile.close();

File Modes

ios::in, ios::out
ios::app, ios::trunc
Combine modes with | operator


ofstream outFile("data.txt", ios::app); // append
outFile << "More text" << endl;
outFile.close();

Formatted Output

Use manipulators
setw(), setprecision()
Fixed and scientific formats


#include 
cout << setw(10) << 123 << endl;
cout << fixed << setprecision(2) << 3.14159 << endl;

Unformatted Output

Use put(), write()
Character or byte-wise output


ofstream outFile("char.txt");
outFile.put('A');
outFile.write("Hello", 5);
outFile.close();

Unformatted Input

Use get(), getline(), read()
Character or binary input


ifstream inFile("char.txt");
char c;
inFile.get(c);
cout << c << endl;
inFile.close();

String Streams

istringstream, ostringstream
Parse strings like files
Useful for conversion


#include 
string data = "10 20 30";
istringstream ss(data);
int x;
while(ss >> x) {
    cout << x << endl;
}

Flushing Streams

Use flush() or endl
Ensure output is written


cout << "Hello, world!" << endl; // flushes
cout << "Hello again!";
cout.flush();

Stream Manipulators

hex, dec, oct
boolalpha, nouppercase


cout << hex << 255 << endl; // ff
cout << boolalpha << true << endl; // true

Stream Buffers

Underlying storage for streams
Use rdbuf() for custom buffer


ofstream out("buf.txt");
streambuf* buf = out.rdbuf();
cout << "Using same buffer as file" << endl;

Error Handling

Check fail(), bad()
Clear errors with clear()


ifstream in("data.txt");
if(in.fail()) {
    cerr << "Read failed!" << endl;
    in.clear(); // reset state
}

Closing Streams

Always close files
Destructor also closes


ofstream out("file.txt");
out << "Some text" << endl;
out.close(); // important!

Exercises

Write numbers 1-10 to a file
Read them back and sum
Use binary mode


// Exercise code here

Quiz

What class is used for writing files?
How to open binary file?
What is flush() used for?


// Answer review in class

Class Discussion: Review Questions

What is the difference between ofstream and fstream?
When should you use ios::app mode?
How can you detect if a file failed to open?
What is the purpose of flush()?
Why do we use reinterpret_cast<char*> for binary data?


// Think and Discuss:
// - File modes
// - Error handling
// - Binary vs text data

In-Class Coding Question

Write a C++ program that:

Opens a file called numbers.txt
Writes the numbers 1–10, each on a new line
Closes the file
Then reads and prints all numbers to the console


// TODO:
// 1. Create ofstream to write numbers
// 2. Close the file
// 3. Reopen with ifstream to read
// 4. Print contents to console

Today, Tuesday Nov 4th

Introduction to Exception Handling
Try, Catch, and Throw in C++
Agriculture-based Examples

What is Exception Handling?

Helps manage unexpected runtime errors.
Prevents the program from crashing suddenly.
Uses try, throw, and catch.

Why Do Farmers Need Error Handling?

Ensures sensor data doesn’t crash systems.
Protects important farm records.
Keeps irrigation or automation running safely.


// Without Exception Handling
int main() {
    int soilMoisture = 100;
    int sensors = 0;
    cout << soilMoisture / sensors; // crash!
}

Basic Syntax

try: risky code.
throw: send out an error.
catch: handle the error safely.


try {
    // risky code
} catch (exceptionType e) {
    // handle problem
}

Example: Divide Crop Yield

Catch division by zero when calculating yield per acre.


try {
    int totalYield = 500;
    int acres = 0;
    if (acres == 0)
        throw runtime_error("No acres found!");
    cout << totalYield / acres;
}
catch (const runtime_error& e) {
    cerr << e.what();
}

💡 Question:

What happens if no catch block matches the error type?
Does the program continue or stop?

Multiple Error Types

Different exceptions can mean different problems.


try {
    throw "Sensor error!";
}
catch (int e) { cout << "Integer error"; }
catch (const char* e) { cout << e; }

Catch-All Handler

Use catch(...) for unknown problems.


try {
    throw "Data lost!";
}
catch (...) {
    cout << "Unknown farm error.";
}

Standard Exception

Use built-in std::exception for simplicity.
Access details with what().


catch (const exception& e) {
    cerr << e.what();
}

Custom Farm Error

You can make your own exception type.


class FarmError : public exception {
public:
    const char* what() const noexcept override {
        return "Farm system error!";
    }
};

Using Custom Farm Error


try {
    throw FarmError();
}
catch (const FarmError& e) {
    cerr << e.what();
}

Example: Sensor Reading

Throw error if temperature sensor gives invalid value.


float readTemp = -100;

try {
    if (readTemp < -50)
        throw runtime_error("Sensor reading invalid!");
    cout << readTemp;
}
catch (const exception& e) {
    cerr << e.what();
}

💡 Question:

Why should we check data before using it in calculations?

Re-Throwing Exceptions

Pass the problem up if it can’t be solved here.


try {
    try { throw runtime_error("Pump error!"); }
    catch (...) { throw; }
}
catch (const exception& e) {
    cerr << e.what();
}

Stack Unwinding

When an error occurs, local variables are destroyed automatically.


struct Crop {
    ~Crop() { cout << "Crop data cleaned up\n"; }
};

int main() {
    try {
        Crop c;
        throw 1;
    } catch (...) {}
}

File Handling Example

Throw error if weather data file is missing.


ifstream file("weather.txt");
if (!file)
    throw runtime_error("File not found!");

Practical Example: Soil Moisture

Handle invalid soil moisture values safely.


float soil = -10;
try {
    if (soil < 0)
        throw runtime_error("Invalid soil reading!");
    cout << soil;
}
catch (const exception& e) {
    cerr << e.what();
}

💡 Question:

What could happen if invalid sensor data isn’t caught?

Handling Exceptions from Functions

Errors can be thrown from helper functions.


void checkPump() { throw runtime_error("Pump offline!"); }

int main() {
    try { checkPump(); }
    catch (const exception& e) { cerr << e.what(); }
}

Exception Best Practices

Use exceptions only for real problems.
Clean up properly before exiting.
Keep code readable for beginners.

Summary

Try–catch blocks make programs safer.
Use meaningful error messages.
Validate farm data before processing.

Today’s Challenge: “Code Quest” 🎮

Write 10 small C++ functions
Each has conditions or loops
Earn 10 points total

Code Quest 💡: Student Edition

1️⃣ Check Even or Odd


// Write a function checkEvenOdd(int n)
// Example:
// checkEvenOdd(4) → "Even"
// checkEvenOdd(7) → "Odd"

2️⃣ Sum of First N Numbers


// Write a loop to calculate sumN(int n)
// Example:
// sumN(3) → 1 + 2 + 3 = 6
// sumN(5) → 15

3️⃣ Find Maximum of Two


// Complete findMax(int a, int b)
// Example:
// findMax(10, 7) → 10
// findMax(-3, 5) → 5

4️⃣ Factorial Calculator


// Loop and multiply numbers from 1 to n
// Example:
// factorial(4) → 24
// factorial(0) → 1

5️⃣ Guessing Game


// Compare secret and guess using if-else
// Example:
// guessGame(5, 5) → "Correct!"
// guessGame(5, 2) → "Try again"

6️⃣ Countdown


// Print countdown from n to 0
// Example:
// countdown(3) → 3 2 1 0

7️⃣ Temperature Advice


// Use chained if statements for t
// Example:
// weatherMsg(5) → "Cold"
// weatherMsg(20) → "Warm"
// weatherMsg(30) → "Hot"

8️⃣ Multiplication Table


// Print 10 lines of n × i
// Example:
// table(3) → 
// 3 × 1 = 3
// 3 × 2 = 6
// ...
// 3 × 10 = 30

9️⃣ Sum of Digits


// Use modulo and division in a while loop
// Example:
// digitSum(123) → 6
// digitSum(505) → 10

🔟 Mini-Battle Score


// Add +10 for wins, -5 for losses in loop
// Example:
// Input: w, w, l, w, l
// Final score → 20

11️ Substring Finder


// Write a function findSubstring(string text, string word)
// Return true if 'word' appears inside 'text'
// (you may use a loop or text.find())

// Example:
// findSubstring("programming", "gram") → true
// findSubstring("hello world", "bye") → false

Code Quest 🎯: Sample Solutions

1️⃣ Check Even or Odd

Use if to check remainder


string checkEvenOdd(int n) {
    if (n % 2 == 0)
        return "Even";
    else
        return "Odd";
}

2️⃣ Sum of First N Numbers


int sumN(int n) {
    int sum = 0;
    for (int i = 1; i <= n; i++)
        sum += i;
    return sum;
}

3️⃣ Find Maximum of Two


int findMax(int a, int b) {
    if (a > b) return a;
    return b;
}

4️⃣ Factorial Calculator


int factorial(int n) {
    int f = 1;
    for (int i = 1; i <= n; i++)
        f *= i;
    return f;
}

5️⃣ Guessing Game


string guessGame(int secret, int guess) {
    if (guess == secret)
        return "Correct!";
    else
        return "Try again";
}

6️⃣ Countdown


void countdown(int n) {
    while (n >= 0) {
        cout << n << " ";
        n--;
    }
}

7️⃣ Temperature Advice


string weatherMsg(int t) {
    if (t < 10) return "Cold";
    else if (t < 25) return "Warm";
    else return "Hot";
}

8️⃣ Multiplication Table


void table(int n) {
    for (int i = 1; i <= 10; i++)
        cout << n << " × " << i
             << " = " << n*i << endl;
}

9️⃣ Sum of Digits


int digitSum(int n) {
    int sum = 0;
    while (n > 0) {
        sum += n % 10;
        n /= 10;
    }
    return sum;
}

🔟 Mini-Battle Score


void miniBattle() {
    int score = 0;
    for (int i = 1; i <= 5; i++) {
        char result;
        cout << "Round " << i << " (w/l): ";
        cin >> result;
        if (result == 'w') score += 10;
        else score -= 5;
    }
    cout << "Final score: " << score;
}

11️⃣ Substring Finder


// Write a function findSubstring(string text, string word)
// Return true if 'word' appears inside 'text'
// (you may use a loop or text.find())

// Example:
// findSubstring("programming", "gram") → true
// findSubstring("hello world", "bye") → false

12️⃣ The `substr()` Function

Extracts part of a string
Syntax: string.substr(start, length)
If length is omitted → goes to end


#include <iostream>
#include <string>
using namespace std;

int main() {
    string word = "programming";
    cout << word.substr(0, 3) << endl;  // "pro"
    cout << word.substr(3, 4) << endl;  // "gram"
    cout << word.substr(7) << endl;    // "ming"
}

Practice: Extract a Word

Given a full sentence string
Use find() and substr()
Extract a specific word (like “world”)


// Example:
string text = "hello world";
int pos = text.find("world");
string result = text.substr(pos);  // "world"

✅ Solution: Substring Finder


#include <iostream>
#include <string>
using namespace std;

bool findSubstring(string text, string word) {
    if (text.find(word) != string::npos)
        return true;
    else
        return false;
}

// Example tests:
int main() {
    cout << boolalpha;
    cout << findSubstring("programming", "gram") << endl; // true
    cout << findSubstring("hello world", "bye") << endl;   // false
}

Today, Tuesday Nov 11th

Recursion
Project Review
Module Review
Homework, Lab

Recursion: The Concept

A function calling itself to solve smaller subproblems.
Each call handles a simpler case until a base case is reached.
Used in divide-and-conquer algorithms.
Stack frames grow with each call.


void greet(int n) {
    if (n == 0) return;
    cout << "Hello\n";
    greet(n - 1);
}

Base Case vs Recursive Case

Base case: stops recursion.
Recursive case: reduces problem size.
Without base case → infinite calls.


void countdown(int n) {
    if (n == 0) {
        cout << "Done!";
        return;
    }
    cout << n << " ";
    countdown(n - 1);
}

Recursion vs Loop

Both repeat actions.
Recursion uses function calls.
Loops use iteration (for, while).


// Recursion
void printR(int n) {
    if (n == 0) return;
    cout << n << " ";
    printR(n - 1);
}

// Loop
for(int i=n;i>0;i--) cout << i << " ";

Example: Factorial (n!)

Classic recursion example.
Each call computes n × (n−1)!
Base case: 0! = 1


int fact(int n) {
    if (n == 0) return 1;
    return n * fact(n - 1);
}

Example: Fibonacci Numbers

Each term = sum of two previous terms.
Recursive structure fits naturally.
High cost due to repeated calls.


int fib(int n) {
    if (n <= 1) return n;
    return fib(n-1) + fib(n-2);
}

Tail Recursion

Recursive call is the last operation.


void tailPrint(int n) {
    if (n == 0) return;
    cout << n << " ";
    tailPrint(n - 1);
}

Advantages of Recursion

Cleaner code for hierarchical tasks.
Useful for tree and graph traversal.
Natural fit for divide-and-conquer.


// Example: Tree traversal
void inorder(Node* root) {
    if (!root) return;
    inorder(root->left);
    cout << root->val << " ";
    inorder(root->right);
}

When to Use Recursion

When problem breaks to smaller identical parts.
When hierarchy or branching is involved.
Use loops when simple repetition suffices.


// Loop better for:
for (int i=0; i<1000; i++) doWork();

// Recursion better for:
searchTree(root);

In-Class Exercise: Recursive Search

Use an array of 50 integers (manually given).
Write a recursive function to find a target number.
Return the index if found, or -1 if not found.
Show only the function signature for now.

Question:
Write a recursive function
find(int arr[], int n, int target, int i)
that searches for target in a 50-element array.

Recursive Find Function (Array Data)

Array of 50 integers preloaded.
Only function signature shown.
Students complete logic themselves.


// Example dataset
int arr[50] = {
  2, 4, 7, 9, 12, 15, 18, 21, 24, 27,
  30, 33, 36, 39, 42, 45, 48, 51, 54, 57,
  60, 63, 66, 69, 72, 75, 78, 81, 84, 87,
  90, 93, 96, 99, 102, 105, 108, 111, 114, 117,
  120, 123, 126, 129, 132, 135, 138, 141, 144, 147
};

// Function signature
int find(int arr[], int n, int target, int i);

Recursive Binary Search

Divides array into halves each call.
Base case: range becomes invalid.
Midpoint checked each recursion.
O(log n) time complexity.


#include <iostream>
using namespace std;

int find(int arr[], int left, int right, int target) {
    if (left > right) return -1;       // base case
    int mid = (left + right) / 2;

    if (arr[mid] == target) return mid;
    if (target < arr[mid])
        return find(arr, left, mid - 1, target);
    else
        return find(arr, mid + 1, right, target);
}

int main() {
    int arr[50] = {
        2, 4, 7, 9, 12, 15, 18, 21, 24, 27,
        30, 33, 36, 39, 42, 45, 48, 51, 54, 57,
        60, 63, 66, 69, 72, 75, 78, 81, 84, 87,
        90, 93, 96, 99, 102, 105, 108, 111, 114, 117,
        120, 123, 126, 129, 132, 135, 138, 141, 144, 147
    };

    int target = 81;
    cout << "Found at index: " << find(arr, 0, 49, target);
}

Questions?

Rock–Paper–Scissors: Project Map

Goal: best of three vs computer.
Key pieces: input, random move, compare, scores.
Control flow: nested loops (rounds, replay).
Functions keep code clear and reusable.

// Headers and std setup
#include <cstdlib>
#include <ctime>
#include <iostream>
using namespace std;

// Forward look: functions handle small tasks
// - compMove(): random computer choice
// - checkPlayerMove(): validate input
// - compare(): who wins this turn?
// - standings & win checks: score and match end

Generating the Computer’s Move

Seed once with srand(time(0)).
rand()%3 → 0,1,2.
Map to Rock, Paper, Scissors.
Return a string choice.


// Returns "Rock", "Paper", or "Scissors"
string compMove() {
    string compMoveA;
    int randomNumber = rand() % 3; // 0..2
    switch (randomNumber) {
        case 0: compMoveA = "Rock";      break;
        case 1: compMoveA = "Paper";     break;
        case 2: compMoveA = "Scissors";  break;
    }
    return compMoveA;
}

Checking Player Input

Accept only exact words.
Return true if valid.
Else false and re-prompt.


// Ensures player typed a valid word
bool checkPlayerMove(string a) {
    bool okMove;
    if (a == "Rock" || a == "Paper" || a == "Scissors") {
        okMove = true;
    } else {
        okMove = false;
    }
    return okMove;
}

Who Wins a Round?

Inputs: computer, player.
All winning triples listed.
Return "computer", "player", or "tie".


// Returns which side wins this round
string compare(string comp, string player) {
    if ((comp=="Scissors" && player=="Paper") ||
        (comp=="Paper"    && player=="Rock")  ||
        (comp=="Rock"     && player=="Scissors")) {
        return "computer";
    } else if (comp == player) {
        return "tie";
    } else {
        return "player";
    }
}

Summaries and Scoreboard

Show choices each round.
Print current scores.
Small helpers keep main() clean.


// Prints chosen moves
void roundSummary(string player, string comp) {
    cout << "You chose " << player
         << ", the computer chose " << comp << '\n';
}

// Note: params are (player, computer) order
void currentStandings(int playerScore, int compScore) {
    cout << "Player- " << playerScore
         << " Computer- " << compScore << '\n';
}

Best-of-Three and Final Standings

Best of three → first to 2.
Return winner string.
Print final totals after a match.


// a = computer round wins, b = player round wins
string checkWin(int a, int b) {
    if (a == 2) return "Computer";
    if (b == 2) return "Player";
    return "nope"; // not yet decided
}

void finalStandings(int compTotal, int playerTotal) {
    cout << "Final scores:\n"
         << "Player- " << playerTotal
         << " Computer- " << compTotal;
}

main(): Setup

Seed RNG once at start.
Round scores vs total matches.
Flags for loops (play, keepGoing).


int main() {
    srand(time(0)); // seed random once

    int playerScoreR = 0, compScoreR = 0; // round scores
    int playerTotal  = 0, compTotal  = 0; // match totals

    string playerMove, compMoveCurrent, winner;
    char again;
    bool keepGoing = true; // replay loop
    bool play = true;      // per-match loop

    // We'll use nested while-loops next...

main(): Play One Match (Input)

Prompt for move each round.
Validate with checkPlayerMove.
Skip scoring if invalid.


while (keepGoing) {
    while (play) { // one best-of-three
        cout << "Make your move! (Rock, Paper, or Scissors)\n";
        cin  >> playerMove;

        if (checkPlayerMove(playerMove)) {
            compMoveCurrent = compMove(); // random computer move
            // ... resolve round (next slide)
        } else {
            cout << "That's not a move!\n";
        }

main(): Round Result & Scoring

Use compare() to decide.
Update round scores.
Print summaries each time.


        string outcome = compare(compMoveCurrent, playerMove);
        if (outcome == "player") {
            playerScoreR++;
            winner = "Player";
            roundSummary(playerMove, compMoveCurrent);
            currentStandings(playerScoreR, compScoreR);
        } else if (outcome == "computer") {
            compScoreR++;
            winner = "Computer";
            roundSummary(playerMove, compMoveCurrent);
            currentStandings(playerScoreR, compScoreR);
        } else {
            cout << "Players made the same move! No points!\n";
            currentStandings(playerScoreR, compScoreR);
        }

main(): Match End Check

When someone reaches 2, match ends.
Increment total matches won.
Exit inner loop (set play=false).


        // Did anyone win the best-of-three?
        string matchWinner = checkWin(compScoreR, playerScoreR);
        if (matchWinner == "Player" || matchWinner == "Computer") {
            cout << matchWinner << " wins!\n";
            if (matchWinner == "Player") {
                playerTotal++;
                cout << "Player Wins!";
            } else {
                compTotal++;
                cout << "Computer Wins!";
            }
            play = false; // end this match
        }
    } // end inner while (play)

main(): Reset & Play Again?

Reset round scores to 0.
Show running totals.
Ask to play another match.


    // Reset per-round scores for the next match
    playerScoreR = 0;
    compScoreR   = 0;

    // Show running totals across matches
    finalStandings(compTotal, playerTotal);

    // Replay prompt
    cout << "Round over! Would you like to play again? (Y/N)";
    char again;
    cin >> again;

    if (again == 'Y' || again == 'y') {
        play = true;       // start a new match
    } else {
        keepGoing = false; // exit outer loop
    }
}
return 0;
}

Suggestions and Small Improvements

Normalize input (capitalize first letter).
Guard invalid cin states.
Extract “play one round” into a function.
Replace magic 2 with a named constant.


// Example: named constant for match length
const int ROUNDS_TO_WIN = 2;

// Example: safe input (future exercise)
// if (!(cin >> playerMove)) { /* clear and re-prompt */ }

Today, Thursday Nov 13th

Review Functions
Review Namespaces
Module Review
Homework, Lab

Function Signature

The function’s name and parameter list form its signature.
Return type is not part of the signature.
The compiler matches calls using the signature.


int add(int a, int b);
// name: add, params: (int, int)

Parameters vs Arguments

Parameters are placeholders in the function definition.
Arguments are the actual values passed at the call site.


void greet(string name);   // parameter
greet("Alice");            // argument

Return Types

Every function specifies a return type.
void means no value is returned.
Return type guides how the function is used.


double square(double x) {
    return x * x;
}

Passing by Value

A copy of the argument is passed to the function.
Original data remains unchanged.


void test(int x) {
    x = 50; // affects only local copy
}

Passing by Reference

The function receives an alias of the argument.
Changes affect the original variable.


void update(int& x) {
    x = 50; // changes caller's variable
}

Constant Parameters

const prevents modification of the parameter.
Useful for large objects passed by reference.


int length(const string& s) {
    return s.size();
}

Default Parameters

Provide fallback values when arguments are omitted.
Placed at the end of the parameter list.


void log(string msg, int level = 1);

Function Overloading

Same name, different parameter lists.
Compiler chooses based on matching signature.


int sum(int a, int b);
double sum(double a, double b);

Variable Scope

Local variables exist only inside the function.
Global variables exist throughout the program.
Local names hide global names.


int x = 10;
void test() {
    int x = 5; // hides global x
}

Returning Multiple Values

A function returns one value directly.
Pairs, structs, or references allow more.


pair getPair() {
    return {3, 7};
}

Helper Functions

Small functions keep code readable.
Reduces repetition.
Makes testing easier.


bool isEven(int x) {
    return x % 2 == 0;
}

Function Documentation

Brief comments explain purpose.
Clarifies input and output expectations.
Helps future readers of the code.


// Returns true if n is prime
bool isPrime(int n) { ... }

Order of Parameters

The sequence of parameter types forms the signature.
Changing the order changes the signature.


void mix(int a, double b);
void mix(double b, int a); // different

Missing Return

Non-void functions must return a value.
Reaching the end without return is undefined.


int test() {
    // no return → unsafe
}

Why We Use Functions

Breaks programs into smaller tasks.
Makes code easier to read and maintain.
Encourages reuse of common logic.


void printLine() {
    cout << "----------\n";
}

What is a Namespace?

A way to group related names together.
Prevents naming conflicts in large programs.
Keeps functions, classes, and variables organized.
Accessed using scope resolution (::).


namespace mathTools {
    int add(int a, int b) {
        return a + b;
    }
}

int x = mathTools::add(3, 4);

The std Namespace

Holds the standard C++ library names.
Includes cout, cin, string, vector, and more.
Created to avoid collisions with user code.
Introduced with C++ standardization.


std::cout << "Hello";
std::string name = "Solo";
std::vector v = {1,2,3};

Brief History of std

Early C++ had no namespaces at all.
Library names sat in the global scope.
C++98 introduced namespaces to solve conflicts.
std created to hold all standard library names.
Helped unify code across compilers.


// Before namespaces
// cout lived in global scope

// After C++98
std::cout << "Now organized";

Using std with ::

Most common way to access names inside std.
Clear and avoids accidental conflicts.
Shows exactly where each name comes from.


std::cout << "Enter age: ";
int age;
std::cin >> age;

using namespace std

Brings all std names into the local scope.
Makes code shorter for small programs.
Not ideal for large projects.
Can cause naming collisions.


using namespace std;

cout << "Shorter to write";
string s = "Hello";

Selective Using

You can import only certain names.
Safer than using the whole namespace.
Keeps the code clear and clean.


using std::cout;
using std::string;

cout << "Clean style";
string name = "Solo";

Why std Matters

Organizes the entire standard library.
Makes code safer in large projects.
Supports development across decades.
Respects the tradition of clean structure.


std::vector data = {1,2,3};
std::sort(data.begin(), data.end());

1. Write a function that returns the absolute value of an integer.

Takes one integer.
Returns positive version.


int absolute(int n);

2. Write a function that counts how many vowels are in a string.

Input: string reference.
Returns number of vowels.


int countVowels(const std::string& text);

3. Write a function that returns true if a character is a digit.

One character input.
Checks 0–9.


bool isDigit(char c);

4. Write a function that returns the middle value of three integers.

Three integer inputs.
Returns the median.


int middleOfThree(int a, int b, int c);

5. Write a function that checks if a string ends with a period.

One string input.
Return true if last char is '.'.


bool endsWithPeriod(const std::string& s);

6. Write a function that multiplies all elements of an integer array by a constant factor.

Array pointer + size + factor.
No return value.


void scaleArray(int arr[], int size, int factor);

7. Write a function that returns the number of words in a sentence.

String input.
Count spaces + 1.


int wordCount(const std::string& s);

8. Write a function that returns whether an integer is within a given range.

Input: value, min, max.
Return true if min ≤ value ≤ max.


bool inRange(int value, int low, int high);

9. Write a function that returns a new string containing only uppercase characters from the original.

String input.
Return filtered uppercase copy.


std::string extractUpper(const std::string& s);

10. Write a function that swaps two integers by reference.

Two integer references.
No return value.


void swapValues(int& a, int& b);

Today, Thursday Nov 13th

Review Functions
Review Namespaces
Module Review
Homework, Lab

History of C

Developed at Bell Labs
Efficient for system programming

// Simple C function
int add(int a, int b){ return a + b; }

Question

What was C originally created for?

A) Games
B) System programming
C) Agriculture robots

History of C++

Created by Bjarne Stroustrup
Added classes to C

// C++ class intro
class Farm{}; Farm f;

Question

C++ extended C by adding…

A) Graphics
B) Classes
C) Crops

Compilation Flow

C++ → Assembly → Machine code
Handled by compiler toolchain

// Assembly sample
mov eax, edi
add eax, esi

Question

Which step comes right after C++ code?

A) Harvesting crops
B) Assembly code
C) Binary sensors

Basic I/O

cin for input
cout for output

int age;
cin >> age;
cout << age;

Question

Which object reads input?

A) cout
B) cin
C) tractor

Variables

Store values
Need a type

int cropCount = 10;

Question

Which is a valid variable?

A) 2corn
B) corn2
C) corn-amount

Multiple Declarations

Same type, many variables

int a, b, c;

Question

Which is correct?

A) int x, y;
B) float 2x;
C) char = 'A';

Initialization

Avoids garbage values

int moisture = 40;

Question

Why initialize?

A) Avoid garbage data
B) Faster tractors
C) Bigger files

Type Casting

Explicit and implicit

double y = (double)5;

Question

Explicit cast uses…

A) (type)
B) tractor
C) semicolon

Scope

Local vs global

int g=0; void f(){int x=5;}

Question

A local variable lives…

A) entire farm
B) inside block
C) until reboot

Strings

Store text

string crop = "Wheat";

Question

Access first letter with…

A) crop(0)
B) crop[0]
C) crop.first

Classes

Blueprint for objects

class Farmer{public:string name;};

Question

A class represents…

A) template
B) tractor wheel
C) kernel

OOP

Encapsulation
Inheritance

class Crop{}; class Corn: public Crop{};

Question

Inheritance means…

A) sharing fields
B) planting crops
C) reading files

Decision Making

If / else based on conditions

if(moisture>50) cout less than "Wet";

Question

Condition executes when…

A) true
B) false
C) random

For Loop

for(int i=0;i<5;i++) cout less than i;

Question

A for loop runs…

A) until condition false
B) forever

While Loop

while(x less than 5){x++;}

Question

While checks condition…

A) before
B) after

Do While

do{x++;}while(x less than 5);

Question

Do-while runs…

A) at least once
B) zero times

Nested Loops

for(r) for(c) print

Question

Nested loops are good for…

A) grids
B) tractors

Break / Continue

if(i==3) continue;

Question

continue means…

A) skip iteration
B) stop loop

Streams

// istream/ostream

Question

Which writes output?

A) ostream
B) farmland

Files

ofstream out("farm.txt");

Question

ofstream is for…

A) writing
B) harvesting

Formatted Output

setw(10)

Question

setw changes…

A) width
B) crop size

String Streams

istringstream ss("10 20");

Question

stringstream helps…

A) parse text
B) plant seeds

Exceptions

try{throw 1;}catch(...){}

Question

Exceptions prevent…

A) crashes
B) crop disease

Complexity

if(a>b)

Question

More paths means…

A) higher complexity
B) larger field

Course Wrap

All core C++ foundations covered
From variables to exceptions

// Mini agri example
if(moisture < 30){ cout<<"Irrigate"; }

Final Question

What should a program do when moisture is low?

A) Recommend irrigation
B) Print random numbers

Today, Thursday Nov. 20th

Build a farm game
Practice Final Exam

1. Game setup: headers and basic structure.

Basic console input and output.
Store player names with string.
Single .cpp file for simplicity.
Declare functions before main().
Simple, reusable functions only.
Each round players pick a crop to earn coins.
Player with the most coins after all rounds wins.

This program uses a simple setup: a Farmer class to store each player’s name and coins, small helper functions to initialize farmers, show the crop menu, read a player’s choice, map that choice to a coin reward, run each round, and finally print the winner after all rounds. The signatures keep the structure clean so the game logic in main() stays easy to follow.

2. Explain the game setup and forward declarations.

#include <iostream> for cin / cout.
#include <string> to store farmer names.
using namespace std; to avoid writing std::.
Declarations specify functions and classes.
All functions in main() declared before main().


// Signantures and setup
class Farmer;
void initFarmer(Farmer& farmer, const string& name);
void printCropMenu();
int readCropChoice(const string& playerName);
int cropReward(int cropChoice);
int askNumberOfRounds();
void printRoundResult(const Farmer& p1, const Farmer& p2, int roundNumber);
void printFinalResult(const Farmer& p1, const Farmer& p2, int rounds);
void playSingleRound(Farmer& p1, Farmer& p2, int roundNumber);

3. Farmer building block: requirements and structure.

Each farmer needs a name.
Each farmer tracks total coins.
No complex methods, just data.
Use a simple C++ class.
Keep all data public to avoid getters/setters.


class Farmer {

};

4. Explain the Farmer class and its role.

Farmer groups together related data.
name: used when asking for choices and scores.
coins: starts at 0 and increases each round.
All data is public for simple access in this game.
No behavior inside the class;.


class Farmer {
public:
    string name;
    int coins;
};

5. Initialize a farmer: requirements and function signature.

Set the farmer’s name.
Set the initial coin count to 0.
Modify an existing Farmer object.
Do not create or return a new object.
Use reference so changes are visible to caller.


void initFarmer(Farmer& farmer, const string& name);

6. Initialize a farmer: implementation and logic.

Assign the provided name directly to farmer.name.
Reset farmer.coins to 0 at the start of every game.
Farmer& farmer passes the object by reference.
const string& name avoids copying the string.
This is a re-usable building block for any farmer.


void initFarmer(Farmer& farmer, const string& name) {
    farmer.name = name;
    farmer.coins = 0;
}

7. Crop menu: requirements and function signature.

Show all available crops and their rewards.
Use very simple reward values.
Use fixed integer choices (0, 1, 2).
Do not read any input here, only print.
Use a void function, no return value.
0) Wheat +2, 1) Corn +3, 2) Cows +4 coins


void printCropMenu();

8. Crop menu: implementation and logic.

Print a short title so players know what to do.
Use one line per option for clarity.
Keep the rewards small and easy to remember.
Match numbers with the later input handling.
Use cout for all output.


void printCropMenu() {
    cout << "Choose your crop (enter the number):\n";
    cout << "  0 = Wheat (+2 coins)\n";
    cout << "  1 = Corn  (+3 coins)\n";
    cout << "  2 = Cows  (+4 coins)\n";
}

9. Read a crop choice: requirements and signature.

Ask one specific farmer for a choice.
Use the farmer’s name in the prompt.
Read an integer from the keyboard.
If input is outside [0, 2], fall back to 0 (Wheat).
Return the validated choice as an int.


int readCropChoice(const string& playerName);

10. Read a crop choice: implementation and validation.

Print a prompt that includes playerName.
Store the answer in a local int choice.
Check if choice is outside the valid range.
Print warning and correct invalid input to 0.
Return the final valid choice value.


int readCropChoice(const string& playerName) {
    int choice;
    cout << playerName << ", enter 0, 1, or 2: ";
    cin >> choice;

if (choice < 0 || choice > 2) {
    cout << "Invalid choice, using Wheat (0).\n";
    choice = 0;
}

return choice;

}

11. Map crop choice to reward: requirements and signature.

Take a validated crop choice (0, 1, or 2).
Return the number of coins for that crop.
Use a simple mapping:
- 0 → 2 coins
- 1 → 3 coins
- 2 → 4 coins
Keep the function pure: no input and no output.
Return an int with the reward.


int cropReward(int cropChoice);

12. Map crop choice to reward: implementation.

Use simple if statements (no complex logic).
Assume the input is already validated (0, 1, or 2).
Return 2 for Wheat, 3 for Corn, 4 for Cows.
Use a final else as a default for Cows.
Keep the function short and easy to read.


int cropReward(int cropChoice) {
    if (cropChoice == 0) {
        return 2; // Wheat
    }
    if (cropChoice == 1) {
        return 3; // Corn
    }
    return 4;     // Cows
}

13. Ask for number of rounds: requirements and signature.

Let the players decide how many rounds to play.
Read an integer from the keyboard.
Enforce range, for example 1 to 10 rounds.
If input is outside range, use a default value (3).
Return the final number of rounds as an int.


int askNumberOfRounds();

14. Ask for number of rounds: implementation and range checking.

Print a prompt that explains the allowed range.
Read the user input into a local variable.
Check if it is smaller than 1 or larger than 10.
If invalid, print a message and set it to 3.
Return the chosen number of rounds.


int askNumberOfRounds() {
    int rounds;
    cout << "How many rounds do you want to play (1-10)? ";
    cin >> rounds;

if (rounds < 1 || rounds > 10) {
    cout << "Invalid number, using 3 rounds.\n";
    rounds = 3;
}

return rounds;

}

15. Print the result after each round: requirements and signature.

Show which round just finished.
Show both farmers’ current coin totals.
Do not change any values; only print.
Use const Farmer& to avoid copying.
Return nothing (type void).


void printRoundResult(const Farmer& p1,
                      const Farmer& p2,
                      int roundNumber);

16. Print the result after each round: implementation.

Print a small header for the round.
Display farmer’s name/coins on separate lines.
Use const Farmer& because we only read data.
Keep the output format consistent every round.
Provide blank line for readability after scores.


void printRoundResult(const Farmer& p1,
                      const Farmer& p2,
                      int roundNumber) {
    cout << "\n=== End of round "
         << roundNumber << " ===\n";
    cout << p1.name << " has "
         << p1.coins << " coins.\n";
    cout << p2.name << " has "
         << p2.coins << " coins.\n\n";
}

17. Print final result and winner: requirements and signature.

Show the total number of rounds played.
Print each farmer’s final coin count.
Announce the winner or a draw.
Use const Farmer& for both farmers.
Return nothing (type void).


void printFinalResult(const Farmer& p1,
                      const Farmer& p2,
                      int rounds);

18. Print final result and winner: implementation.

Print a clear final header.
Show both farmers’ total coins.
Compare the two values.
If one is larger, declare that farmer the winner.
If they are equal, print that it is a draw.


void printFinalResult(const Farmer& p1,
                      const Farmer& p2,
                      int rounds) {
    cout << "\n=== Final result after "
         << rounds << " rounds ===\n";
    cout << p1.name << ": "
         << p1.coins << " coins\n";
    cout << p2.name << ": "
         << p2.coins << " coins\n";

if (p1.coins > p2.coins) {
    cout << p1.name
         << " wins the farm game!\n";
} else if (p2.coins > p1.coins) {
    cout << p2.name
         << " wins the farm game!\n";
} else {
    cout << "It is a draw.\n";
}

}

19. Play a single round: requirements and signature.

Print the round header.
Show the crop menu once.
Ask each farmer to choose a crop.
Update both farmers’ coin totals.
Call printRoundResult at the end of the round.


void playSingleRound(Farmer& p1,
                     Farmer& p2,
                     int roundNumber);

20. Play a single round: implementation and flow.

Print a header such as “Round 1”.
Call printCropMenu() once.
Call readCropChoice for each farmer.
Compute each reward using cropReward.
Add rewards to each farmer and show result.


void playSingleRound(Farmer& p1,
                     Farmer& p2,
                     int roundNumber) {
    cout << "\n=== Round "
         << roundNumber << " ===\n";
    printCropMenu();

int choice1 = readCropChoice(p1.name);
int choice2 = readCropChoice(p2.name);

int reward1 = cropReward(choice1);
int reward2 = cropReward(choice2);

p1.coins += reward1;
p2.coins += reward2;

printRoundResult(p1, p2, roundNumber);

}

21. Main game loop: requirements and signature.

Ask for both farmers’ names.
Initialize each Farmer with 0 coins.
Ask for the number of rounds.
Run a for loop calling playSingleRound.
Call printFinalResult at the end.


int main();

22. Main game loop: full implementation.

Read names using getline to accept spaces.
Use initFarmer to set name and coins.
Call askNumberOfRounds once.
Loop from 1 to rounds and call playSingleRound.
Finally, call printFinalResult and return 0.


int main() {
    Farmer p1;
    Farmer p2;

cout << "Enter name for Farmer 1: ";
getline(cin, p1.name);
if (p1.name.empty()) {
    p1.name = "Farmer 1";
}

cout << "Enter name for Farmer 2: ";
string name2;
getline(cin, name2);
if (name2.empty()) {
    name2 = "Farmer 2";
}

initFarmer(p1, p1.name);
initFarmer(p2, name2);

int rounds = askNumberOfRounds();

for (int r = 1; r <= rounds; ++r) {
    playSingleRound(p1, p2, r);
}

printFinalResult(p1, p2, rounds);

return 0;

}

Today, Tuesday Nov. 25th

Thanksgiving dinner

Exam Structure

Tuesday, Dec. 9, 3PM

Dec. 9th at 3PM in Baun 214
20 total questions
18 multiple choice and 2 written questions
Each module contributes 1–2 questions
Exam duration: 1hour 20min
Paper exam, closed book
Bring pens only
One paper page summary sheet (both sides)

How to Prepare

Review the midterm questions, which form about 50 percent of the final exam
Review slides, labs, zyBooks homework, GitHub, and the project
Sample Questions PDF 1
Sample Questions PDF 2
Sample Questions PDF 3
Sample Questions PDF 4

1. Function 1 – printWelcome: explanation.

Print a simple Thanksgiving banner. No parameters and no return value. Called at the start of the program.


void printWelcome();

2. Function 1 – printWelcome: implementation.

Prints several decorative lines. Only outputs text. No input or logic required.


void printWelcome() {
    cout << "==============================\n";
    cout << "  Thanksgiving Dinner Planner \n";
    cout << "==============================\n\n";
}

3. Function 2 – askHostName: explanation.

Asks the host for their name. Accepts full names including spaces. Returns the final name as text.


string askHostName();

4. Function 2 – askHostName: implementation.

Reads a line of text. Uses a default name if empty. Returns the chosen name.


string askHostName() {
    cout << "What is your name (the host)? ";
    string name;
    getline(cin, name);

    if (name.empty()) {
        name = "Host";
    }

    cout << "Welcome, " << name << "!\n\n";
    return name;
}

5. Function 3 – askGuestCount: explanation.

Asks how many guests will come. Valid range is 1 to 20. Defaults to 4 if invalid.


int askGuestCount();

6. Function 3 – askGuestCount: implementation.

Reads a number. Checks the allowed range. Returns the corrected result.


int askGuestCount() {
    cout << "How many guests will come (1-20)? ";
    int guests;
    cin >> guests;

    if (guests < 1 || guests > 20) {
        cout << "Number out of range, using 4 guests.\n";
        guests = 4;
    }

    cin.ignore(numeric_limits<streamsize>::max(), '\n');
    return guests;
}

7. Function 4 – askDishCount: explanation.

Asks how many dishes will be prepared. Valid range is 1 to 15. Uses default 5 when invalid.


int askDishCount();

8. Function 4 – askDishCount: implementation.

Reads and validates the number of dishes. Ensures it is within the allowed range. Returns the final count.


int askDishCount() {
    cout << "How many different dishes (1-15)? ";
    int count;
    cin >> count;

    if (count < 1 || count > 15) {
        cout << "Number out of range, using 5 dishes.\n";
        count = 5;
    }

    cin.ignore(numeric_limits<streamsize>::max(), '\n');
    return count;
}

9. Function 5 – askDishName: explanation.

Asks for one dish name. Accepts spaces in the name. Uses a default like “Dish 1” if empty.


string askDishName(int index);

10. Function 5 – askDishName: implementation.

Reads a full line. Checks for empty input. Returns safe dish name.


string askDishName(int index) {
    cout << "Enter name for dish " << index << ": ";
    string name;
    getline(cin, name);

    if (name.empty()) {
        name = "Dish " + to_string(index);
    }

    return name;
}

11. Function 6 – collectDishes: explanation.

Collects several dish names. Calls askDishName repeatedly. Stores each result in a list.


vector<string> collectDishes(int count);

12. Function 6 – collectDishes: implementation.

Loops from 1 to the dish count. Reads each name. Returns the vector of dishes.


vector<string> collectDishes(int count) {
    vector<string> dishes;

    for (int i = 1; i <= count; ++i) {
        string dish = askDishName(i);
        dishes.push_back(dish);
    }

    return dishes;
}

13. Function 7 – printMenu: explanation.

Prints all dishes in order. Shows dish numbers. Output only, no return value.


void printMenu(const vector<string>& dishes);

14. Function 7 – printMenu: implementation.

Loops through dish list. Prints each dish on its own line. Adds a small header.


void printMenu(const vector<string>& dishes) {
    cout << "\nThanksgiving Menu:\n";

    for (size_t i = 0; i < dishes.size(); ++i) {
        cout << "  " << (i + 1) << ". " << dishes[i] << "\n";
    }

    cout << "\n";
}

15. Function 8 – pickRandomDish: explanation.

Selects one dish at random. Requires the dish list. Returns one dish name.


string pickRandomDish(const vector<string>& dishes);

16. Function 8 – pickRandomDish: implementation.

Computes a random index. Returns the dish at that index. Handles empty list safely.


string pickRandomDish(const vector<string>& dishes) {
    if (dishes.empty()) {
        return "No dishes available";
    }

    int index = rand() % dishes.size();
    return dishes[index];
}

17. Function 9 – estimateTurkeySize: explanation.

Estimates turkey amount needed. Uses pounds per guest rule. Returns the total pounds.


double estimateTurkeySize(int guestCount);

18. Function 9 – estimateTurkeySize: implementation.

Multiplies guest count by constant. Returns the computed weight. No printing done here.


double estimateTurkeySize(int guestCount) {
    const double poundsPerGuest = 1.5;
    double total = guestCount * poundsPerGuest;
    return total;
}

19. Function 10 – printDinnerSummary: explanation.

Prints host name, guest count, and turkey size. Summarizes the core dinner plan. No return value.


void printDinnerSummary(const string& host,
                        int guests,
                        double turkey);

20. Function 10 – printDinnerSummary: implementation.

Prints a clear header. Shows the three pieces of information. Ends with a blank line.


void printDinnerSummary(const string& host,
                        int guests,
                        double turkey) {
    cout << "\nDinner summary\n";
    cout << "Host: " << host << "\n";
    cout << "Guests: " << guests << "\n";
    cout << "Turkey: " << turkey
         << " pounds (approx.)\n\n";
}

21. Function 11 – Guest class: explanation.

Stores basic guest info. Includes name and turkey preference. Simple structure for beginners.


class Guest {
public:
    string name;
    bool eatsTurkey;
};

22. Function 11 – Guest class: small usage example.

Shows how to create and fill a Guest. Name is text, eatsTurkey is true or false. Can be stored in a vector.


Guest g;
g.name = "Alice";
g.eatsTurkey = true;

23. Function 12 – readGuest: explanation.

Reads a single guest. Collects name and turkey preference. Returns a Guest object.


Guest readGuest(int index);

24. Function 12 – readGuest: implementation.

Reads name with full line input. Asks y/n for turkey preference. Cleans up the input buffer.


Guest readGuest(int index) {
    Guest g;

    cout << "Guest " << index << " name: ";
    getline(cin, g.name);
    if (g.name.empty()) {
        g.name = "Guest " + to_string(index);
    }

    cout << "Does " << g.name
         << " eat turkey (y/n)? ";
    char answer = 'y';
    cin >> answer;
    cin.ignore(numeric_limits<streamsize>::max(), '\n');

    g.eatsTurkey = (answer == 'y' || answer == 'Y');
    return g;
}

25. Function 13 – printGuestTurkeyChoices: explanation.

Prints each guest’s turkey preference. Loops over the list of Guests. Output only.


void printGuestTurkeyChoices(
    const vector<Guest>& guests);

26. Function 13 – printGuestTurkeyChoices: implementation.

Iterates through the vector. Prints the correct message for each guest. Ends with blank line.


void printGuestTurkeyChoices(
    const vector<Guest>& guests) {
    cout << "\nTurkey choices:\n";

    for (size_t i = 0; i < guests.size(); ++i) {
        const Guest& g = guests[i];
        if (g.eatsTurkey) {
            cout << g.name
                 << " will eat turkey.\n";
        } else {
            cout << g.name
                 << " prefers side dishes.\n";
        }
    }

    cout << "\n";
}

27. Function 14 – playRandomSuggestion: explanation.

Suggests one random dish for fun. Uses pickRandomDish internally. No return value.


void playRandomSuggestion(
    const vector<string>& dishes);

28. Function 14 – playRandomSuggestion: implementation.

Checks if there are any dishes. Calls pickRandomDish. Prints the random result.


void playRandomSuggestion(
    const vector<string>& dishes) {
    if (dishes.empty()) {
        cout << "No dishes to suggest.\n";
        return;
    }

    string suggestion = pickRandomDish(dishes);
    cout << "Random dish suggestion: "
         << suggestion << "\n";
}

29. Function 15 – mainGameFlow: explanation.

Connects all earlier functions. Reads host and guests. Collects dishes. Prints menu and summary, plus a random suggestion.


int main();

30. Function 15 – mainGameFlow: implementation.

Seeds randomness. Calls all helper functions in order. Ends the program cleanly.


int main() {
    srand(static_cast<unsigned int>(time(NULL)));

    printWelcome();

    string host = askHostName();

    int guestCount = askGuestCount();
    int dishCount = askDishCount();

    vector<Guest> guests;
    for (int i = 1; i <= guestCount; ++i) {
        Guest g = readGuest(i);
        guests.push_back(g);
    }
    printGuestTurkeyChoices(guests);

    vector<string> dishes = collectDishes(dishCount);
    printMenu(dishes);

    double turkey = estimateTurkeySize(guestCount);
    printDinnerSummary(host, guestCount, turkey);

    playRandomSuggestion(dishes);

    return 0;
}

Today, Tuesday Dec. 2nd

```
bool isCoffeeHot(double temperature);
```
```
int grindBeans(int grams);
```
```
double brewCoffee(int strengthLevel);
```
```
void addMilk(double amount);
```
```
string selectBeanType(int choice);
```
```
bool isCupFull(int currentLevel);
```
```
double calculateCaffeine(int shots);
```
```
void warmCup();
```

string roastLevelDescription(string level);

```
int refillWaterTank(int currentLevel);
```

bool isCoffeeHot(double temperature);

Return true if temperature is above a hot threshold (for example 60.0)
Return false otherwise
Temperature is given in degrees Celsius
Do not modify the parameter value


// Example
double t1 = 72.5;
double t2 = 45.0;

bool hot1 = isCoffeeHot(t1);  // true
bool hot2 = isCoffeeHot(t2);  // false

int grindBeans(int grams);

Parameter grams is the amount of beans put in the grinder
Return the number of cups that can be brewed from this amount
Assume a fixed ratio (for example 10 grams per cup)
For values less than one cup, return 0


// Example
int cups1 = grindBeans(25);  // 2
int cups2 = grindBeans(7);   // 0

double brewCoffee(int strengthLevel);

strengthLevel is an integer from 1 (mild) to 5 (strong)
Return the brewing time in minutes
Higher strengthLevel means longer brewing time
If strengthLevel is outside 1–5, clamp to the nearest valid value


// Example
double tMild   = brewCoffee(1);  // e.g. 3.0
double tStrong = brewCoffee(5);  // e.g. 6.0
double tClamp  = brewCoffee(8);  // treated as 5

void addMilk(double amount);

amount is given in milliliters
Add the given amount of milk to the current cup
If amount is negative, add nothing
Print or log the new total milk amount in the cup


// Example
addMilk(30.0);   // "Added 30 ml of milk"
addMilk(-10.0);  // ignored, no change

std::string selectBeanType(int choice);

choice is a menu number from 1 to 3
1 = "Arabica", 2 = "Robusta", 3 = "Blend"
Return "Unknown" for any other value
Function does not print anything, it only returns the name


// Example
std::string a = selectBeanType(1);  // "Arabica"
std::string r = selectBeanType(2);  // "Robusta"
std::string x = selectBeanType(9);  // "Unknown"

bool isCupFull(int currentLevel);

currentLevel is the fill level in milliliters
Assume the cup capacity is 250 ml
Return true if currentLevel is greater than or equal to capacity
Return false otherwise


// Example
bool full1 = isCupFull(180);  // false
bool full2 = isCupFull(260);  // true

double calculateCaffeine(int shots);

shots is the number of espresso shots
Assume one shot has 80 mg of caffeine
Return the total caffeine amount in milligrams
If shots is negative, treat it as 0


// Example
double c1 = calculateCaffeine(1);   // 80.0
double c2 = calculateCaffeine(3);   // 240.0
double c3 = calculateCaffeine(-1);  // 0.0

void warmCup();

No parameters
Simulate warming the cup with hot water
May print messages such as "Warming cup..."
Does not return a value


// Example
warmCup();  // "Warming cup..." then "Cup is warm."

std::string roastLevelDescription(std::string level);

level is a word such as "light", "medium", or "dark"
Return a short description for the given level
Ignore case when comparing level
Return "Unknown roast level" for any other value


// Example
std::string d1 = roastLevelDescription("light");
// "Bright and mild flavor"

std::string d2 = roastLevelDescription("dark");
// "Bold flavor with stronger bitterness"

int refillWaterTank(int currentLevel);

currentLevel is the current water level in milliliters
Assume the tank capacity is 2000 ml
Return how many milliliters must be added to reach full capacity
If currentLevel is already above capacity, return 0


// Example
int add1 = refillWaterTank(500);   // 1500
int add2 = refillWaterTank(2100);  // 0

Questions?

Thanks

Course Syllabus – Fall 2025

Course Code: COMP 051
Units: 3
Time: Tue/Thu 03:00–04:45 PM
Location: Baun Hall 214

Instructor & TA

Instructor: Dr. Berhe, CTC 117
Email: sberhe@pacific.edu
TA: Daniel Ming
Email: d_ming@u.pacific.edu
Office Hours: TBD

Course Resources

Course Description

This course provides an introduction to programming with C++, covering both procedural and object-oriented approaches. Students begin with the fundamentals of variables, control flow, loops, arrays, and functions, then progress to advanced topics such as classes, inheritance, pointers, recursion, and exception handling.

Course Topics

Introduction to C++
Variables and Assignments
Branches (Conditionals)
Loops
Arrays and Vectors
User-Defined Functions
Objects and Classes
Inheritance
Streams (I/O)
Recursion
Pointers
Exceptions

Course Goals by Terms

C++, Compiler, Linker, Variables, Data Types, Constants, Operators, Assignments, Expressions, Conditionals, Branches, If/Else, Switch, Loops, For, While, Do-While, Arrays, Vectors, Strings, Functions, Parameters, Return Values, Scope, Objects, Classes, Encapsulation, Constructors, Destructors, Inheritance, Polymorphism, Virtual Functions, Streams, cin, cout, File I/O, Recursion, Call Stack, Pointers, References, Dynamic Memory, Exceptions, Try/Catch, Error Handling, Header Files, Namespaces, Standard Library, Templates, STL, Iterators, Containers, Algorithm Library, Sorting, Searching, Compilation Process, Debugging, Testing, Code Reuse, Modularization, Maintainability.

Grading Schema

Attendance: 5%
Homework: 15%
Labs: 15%
Project: 30%
Midterm Exam: 15%
Final Exam: 20% (cumulative)

Policies

Late Work: 20% penalty; extensions only if requested before deadline by email.
Attendance: Required and tracked; email in advance if absent.
Collaboration & AI: Collaboration allowed on labs; work must be your own. AI tools allowed if you understand the output.

University Policies

ADA Accommodations: Contact SSD (ssd@pacific.edu).
Honor Code: Academic honesty required; violations reported.
Assessment: Student work may be retained for program evaluation.
Support Services: Tutoring, Writing Center, Care Managers.

WelcomeIntroduction to Computer Science

Before Operating Systems

Bell Labs and AT&T

History of C

Why C?

C Code

Assembly

Machine Code

How C Becomes Machine Code

Start Engine (C Code)

History of C++

Why C++?

Basic I/O

Variables

Expressions

Decisions

Loops: for

Loops: while

Functions

Arrays

Strings

Classes (C++)

How This Course Runs

Today, Thursday Aug 28th

Develop C++ Caclulator

Questions?

Today, Thursday Aug 28th

Questions?

Today, Tuesday Nov. 18th

Introduction to Variables

Quiz: Introduction

Common Data Types

Quiz: Data Types

Key Takeaways

Variable Declaration

Quiz: Declaration

Multiple Declarations

Quiz: Multiple Declaration

Key Takeaways

Variable Initialization

Quiz: Initialization

Initialization Tips

Quiz: Tips

Key Takeaways

Assignment

Quiz: Assignment

Multiple Assignments

Quiz: Multiple Assignment

Key Takeaways

Reassignment

Quiz: Reassignment

Tips for Reassignment

Quiz: Tips

Key Takeaways

Hands-On Practice 1

Hands-On Practice 2

Hands-On Practice 3

Memory Size: int

Memory Size: float

Memory Size: double

Memory Size: char

Memory Size: bool

Memory Size: string

Constants (const)

Type Modifiers

Type Casting / Conversion

Input & Output

Scope & Lifetime of Variables

Default Values

Enumerations (enum)

Pointers (Intro)

Basic IO: Introduction

Input Multiple Variables

Formatted Output

Input Validation

Input & Output with Strings

Today, Thursday Sept 4th

Introduction to Variable Naming

Basic Rules

Case Sensitivity

Welcome
Introduction to Computer Science