C++ Programming LearnModern C++

Modern C++

auto, lambda, smart pointers, move semantics

Course Introduction

beginner5m

Learning Objectives

By the end of this course, students should be able to:

Understand basic programming concepts
Write basic C++ programs
Use variables and data types
Take input and produce output
Use operators and expressions
Make decisions using conditional statements
Repeat operations using loops
Create and use functions
Work with arrays and strings
Understand pointers and references
Understand structures
Understand Object-Oriented Programming
Create classes and objects
Apply inheritance and polymorphism
Work with files
Use the C++ Standard Library
Solve programming problems

What is Programming?

beginner5m

Definition

Programming is the process of writing instructions that tell a computer how to perform a task.

Example Problem

Calculate the average marks of a student.

A human might think:

text

Get marks
Add marks
Divide by number of subjects
Display result

A computer needs these instructions expressed in a programming language.

Program

A program is a set of instructions written to solve a particular problem.

cpp

#include <iostream>

int main()
{
    std::cout << "Hello World!";
    return 0;
}

What is C++?

beginner5m

C++ is a general-purpose, compiled programming language that supports procedural, object-oriented, and generic programming.

Why Learn C++?

Learning programming fundamentals
Data structures and algorithms
Competitive programming
Game development
System software
Embedded systems
High-performance applications
Operating systems
Software engineering

Compiler

beginner10m

A computer does not directly understand normal C++ source code. The source code is processed by a compiler.

text

C++ Source Code
       |
    Compiler
       |
Machine Code
       |
    Program
       |
      CPU

Important Terms

Source Code

Code written by the programmer.

Compiler

Software that translates source code into machine-executable code.

Executable

The resulting program that the computer can execute.

Installing C++

beginner10m

Students need:

C++ compiler
Code editor / IDE
Terminal or build environment

Possible Setups

Visual Studio
VS Code with a C++ compiler
Code::Blocks
Other C++ IDEs
Online C++ compiler

First C++ Program

beginner15m

cpp

#include <iostream>

int main()
{
    std::cout << "Hello World!";
    return 0;
}

Line-by-Line Explanation

Line 1: `#include <iostream>`

This includes the standard input/output library. We need it for std::cout and std::cin.

Line 2: `int main()`

main() is the entry point of a C++ program. Program execution begins from main().

`{ }`

These define a block of code.

`std::cout`

Used to display output.

`return 0`

Indicates that the program finished successfully.

Printing Output

beginner10m

Basic Output

cpp

#include <iostream>

int main()
{
    std::cout << "Hello";
    return 0;
}

Multiple Outputs

cpp

std::cout << "Hello";
std::cout << "World";

Output: HelloWorld

New Line

cpp

std::cout << "Hello\n";
std::cout << "World";

Output:

text

Hello
World

Or:

cpp

std::cout << "Hello" << std::endl;

Multiple Values

cpp

std::cout << "Age: " << 20;

Output: Age: 20

Comments

beginner5m

Comments are ignored by the compiler.

Single-line Comment

cpp

// This is a comment

Multi-line Comment

cpp

/*
   This is
   a multi-line
   comment
*/

Teaching Point: Comments are for humans, not for the computer.

Good Example

cpp

// Calculate total price
double total = price * quantity;

Variables

beginner10m

Definition

A variable is a named location used to store data.

cpp

int age = 20;

Think of it as:

text

age
 |
+------+
|  20  |
+------+

Variable Declaration

cpp

int age;

Assignment

cpp

age = 20;

Declaration + Initialization

cpp

int age = 20;

Data Types

beginner10m

Important Beginner Data Types

Type	Example	Purpose
`int`	`10`	Whole numbers
`float`	`10.5f`	Decimal numbers
`double`	`10.5`	More precise decimals
`char`	`'A'`	Single character
`bool`	`true`	True/false
`std::string`	`"Ram"`	Text

Examples

cpp

int age = 20;
double salary = 50000.50;
char grade = 'A';
bool passed = true;
std::string name = "Ram";

For strings, include #include <string>.

Character vs String

beginner5m

Important Beginner Concept

Character: 'A' (single quotes)

String: "A" (double quotes)

Character uses single quotes.

String uses double quotes.

Example

cpp

char c = 'A';      // Character
std::string s = "A"; // String

Common Mistake: Students often confuse 'A' (char) with "A" (string).

Constants

beginner5m

Sometimes a value should not change.

cpp

const double PI = 3.14159;

After this, PI = 5; is not allowed.

Teaching Example

cpp

const double TAX_RATE = 0.13;

double calculateTax(double amount)
{
    return amount * TAX_RATE;
}

Why constants? They make programs safer and easier to understand. If a value is named and constant, programmers know it won't change accidentally.

Input

beginner10m

Use std::cin.

cpp

int age;

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

std::cout << "You are " << age << " years old.";

Multiple Inputs

cpp

int a, b;

std::cin >> a >> b;

Students can enter: 10 20

Example - Student Information

beginner10m

cpp

#include <iostream>
#include <string>

int main()
{
    std::string name;
    int age;

    std::cout << "Enter your name: ";
    std::cin >> name;

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

    std::cout << "Name: " << name << "\n";
    std::cout << "Age: " << age << "\n";

    return 0;
}

Arithmetic Operators

beginner10m

Operator	Meaning
`+`	Addition
`-`	Subtraction
`*`	Multiplication
`/`	Division
`%`	Modulus

Example

cpp

int a = 10;
int b = 3;

std::cout << a + b;  // 13
std::cout << a - b;  // 7
std::cout << a * b;  // 30
std::cout << a / b;  // 3 (integer division!)
std::cout << a % b;  // 1

Integer Division

beginner5m

Very Important!

cpp

int result = 10 / 3;

Result: 3 (not 3.3333)

Because both operands are integers.

Compare

cpp

double result = 10.0 / 3;

Result: 3.3333

Common Mistake: Students forget that integer division truncates the decimal part.

Assignment Operators

beginner5m

text

=
+=
-=
*=
/=
%=

Example

cpp

int x = 10;
x += 5;  // x is now 15
x -= 3;  // x is now 12
x *= 2;  // x is now 24
x /= 4;  // x is now 6
x %= 4;  // x is now 2

Increment and Decrement

beginner10m

cpp

x++;

Equivalent conceptually to: x = x + 1;

Similarly:

cpp

x--;

means: x = x - 1;

Prefix vs Postfix

cpp

int a = 5;
int b = a++;  // b = 5, a = 6 (postfix: use then increment)
int c = ++a;  // c = 7, a = 7 (prefix: increment then use)

Relational Operators

beginner5m

Used to compare values.

text

>
<
>=
<=
==
!=

Example

cpp

int age = 20;
std::cout << (age >= 18);  // 1 (true)
std::cout << (age < 18);   // 0 (false)

Note: In C++, true is represented as 1 and false as 0 when printed.

= vs ==

beginner5m

Very Important!

cpp

x = 10;    // Assignment: Assign 10 to x
x == 10    // Comparison: Is x equal to 10?

Common Mistake

cpp

if (x = 10)  // WRONG: This assigns 10 to x!
{
    // Always executes because 10 is truthy
}

Correct:

cpp

if (x == 10)  // CORRECT: This checks equality
{
    // Executes only if x is 10
}

Conditional Statements

beginner20m

if

cpp

if (age >= 18)
{
    std::cout << "Adult";
}

if-else

cpp

if (age >= 18)
{
    std::cout << "Adult";
}
else
{
    std::cout << "Minor";
}

else if

cpp

if (marks >= 80)
{
    std::cout << "A";
}
else if (marks >= 60)
{
    std::cout << "B";
}
else if (marks >= 40)
{
    std::cout << "C";
}
else
{
    std::cout << "Fail";
}

Logical Operators

beginner10m

AND (`&&`)

Both conditions must be true.

cpp

if (age >= 18 && age <= 60)
{
    std::cout << "Valid age";
}

OR (`||`)

At least one condition must be true.

cpp

if (day == "Saturday" || day == "Sunday")
{
    std::cout << "Weekend";
}

NOT (`!`)

Reverses a Boolean condition.

cpp

if (!isFinished)
{
    std::cout << "Still running";
}

switch

beginner15m

Useful when comparing one value against multiple fixed choices.

cpp

int choice;
std::cin >> choice;

switch (choice)
{
    case 1:
        std::cout << "Add";
        break;

    case 2:
        std::cout << "Delete";
        break;

    case 3:
        std::cout << "Exit";
        break;

    default:
        std::cout << "Invalid choice";
}

Teaching Point: Explain the purpose of break. Without it, execution "falls through" to the next case.

Loops

beginner15m

Why Loops?

Suppose we need to print:

text

Without a loop:

cpp

std::cout << 1;
std::cout << 2;
std::cout << 3;
std::cout << 4;
std::cout << 5;

With a loop:

cpp

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

for Loop

beginner10m

Syntax

cpp

for (initialization; condition; update)
{
    // statements
}

Example

cpp

for (int i = 1; i <= 10; i++)
{
    std::cout << i << "\n";
}

How a for Loop Executes

beginner10m

For:

cpp

for (int i = 1; i <= 3; i++)

Execution Trace

text

i = 1
 |
condition true (1 <= 3)
 |
execute body
 |
i++
 |
condition true (2 <= 3)
 |
execute body
 |
i++
 |
condition true (3 <= 3)
 |
execute body
 |
i++
 |
condition false (4 <= 3)
 |
stop

while Loop

beginner10m

cpp

int i = 1;

while (i <= 5)
{
    std::cout << i << "\n";
    i++;
}

Use while when repetition depends primarily on a condition.

Example

cpp

int number;
std::cout << "Enter a positive number: ";
std::cin >> number;

while (number < 0)
{
    std::cout << "Invalid! Try again: ";
    std::cin >> number;
}

do-while

beginner10m

cpp

int i = 1;

do
{
    std::cout << i << "\n";
    i++;
}
while (i <= 5);

Important Difference

do-while executes the body at least once.

Example

cpp

int choice;

do
{
    std::cout << "1. Play\n";
    std::cout << "2. Settings\n";
    std::cout << "3. Exit\n";
    std::cout << "Enter choice: ";
    std::cin >> choice;
}
while (choice != 3);

break and continue

beginner10m

break

Stops the loop.

cpp

for (int i = 1; i <= 10; i++)
{
    if (i == 5)
        break;

    std::cout << i << "\n";
}

Output: 1 2 3 4

continue

Skips the current iteration.

cpp

for (int i = 1; i <= 5; i++)
{
    if (i == 3)
        continue;

    std::cout << i << "\n";
}

Output: 1 2 4 5

Functions

intermediate20m

Why Functions?

Functions help:

Organize code
Reuse code
Reduce duplication
Make programs easier to understand
Break large problems into smaller problems

Simple Function

cpp

void greet()
{
    std::cout << "Hello";
}

Call: greet();

Function Parameters

intermediate10m

cpp

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

Call: greet("Ram");

Multiple Parameters

cpp

void add(int a, int b)
{
    std::cout << a + b;
}

Call: add(10, 20);

Return Values

intermediate10m

cpp

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

Usage:

cpp

int result = add(10, 20);
std::cout << result;  // 30

Function That Returns Boolean

cpp

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

Usage:

cpp

if (isEven(4))
{
    std::cout << "Even";
}

Function Structure

intermediate10m

Teach students to identify:

cpp

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

Part	Meaning
`int`	Return type
`add`	Function name
`int a`	Parameter
`int b`	Parameter
`return`	Sends value back

Function Declaration vs Definition

Declaration (prototype):

cpp

int add(int a, int b);

Definition:

cpp

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

Arrays

intermediate15m

An array stores multiple values of the same type.

cpp

int marks[5];

Initialize:

cpp

int marks[5] = {80, 70, 90, 60, 85};

Partial Initialization

cpp

int arr[5] = {10, 20};  // {10, 20, 0, 0, 0}

Zero Initialization

cpp

int arr[5] = {};  // {0, 0, 0, 0, 0}

Array Indexing

intermediate10m

C++ arrays start at index 0.

text

Index:   0   1   2   3   4
         |   |   |   |   |
Marks:  80  70  90  60  85

Therefore: marks[0] is 80.

cpp

std::cout << marks[0];  // 80
std::cout << marks[2];  // 90

Common Mistake: Accessing marks[5] on an array of size 5 is out of bounds!

Arrays + Loops

intermediate15m

cpp

int marks[5] = {80, 70, 90, 60, 85};

for (int i = 0; i < 5; i++)
{
    std::cout << marks[i] << "\n";
}

This is an important point where students begin combining concepts.

Finding Maximum

cpp

int marks[5] = {80, 70, 90, 60, 85};
int max = marks[0];

for (int i = 1; i < 5; i++)
{
    if (marks[i] > max)
    {
        max = marks[i];
    }
}

std::cout << "Maximum: " << max;

Strings

intermediate10m

cpp

std::string name = "Abhay";

Useful Operations

cpp

name.length();     // 5
name.empty();      // false

Concatenation

cpp

std::string first = "Hello ";
std::string second = "World";
std::string result = first + second;  // "Hello World"

Accessing Characters

cpp

std::string name = "Hello";
std::cout << name[0];  // H
std::cout << name[4];  // o

getline()

intermediate10m

Difference

cpp

std::cin >> name;

Reads one whitespace-delimited value.

cpp

std::getline(std::cin, name);

Reads a complete line.

Example

cpp

std::string fullName;

std::cout << "Enter your full name: ";
std::getline(std::cin, fullName);

std::cout << "Hello, " << fullName;

Pointers

intermediate25m

Introduce pointers only after students understand variables.

A pointer stores an address.

cpp

int x = 10;
int* p = &x;

Here:

text

x  -> value
&x -> address
p  -> address stored in pointer
*p -> value at that address

Key Operators

Operator	Meaning
`&`	Address-of
`*`	Dereference

Pointer Example

intermediate15m

cpp

int x = 10;
int* p = &x;

std::cout << x << "\n";    // 10
std::cout << &x << "\n";   // address of x
std::cout << p << "\n";    // same address
std::cout << *p << "\n";   // 10 (dereference)

Modifying via Pointer

cpp

int x = 10;
int* p = &x;

*p = 20;  // Change value at address

std::cout << x;  // 20

References

intermediate15m

cpp

int x = 10;
int& ref = x;

ref becomes another name for x.

cpp

ref = 20;
std::cout << x;  // 20

References vs Pointers

Feature	Reference	Pointer
Syntax	`int& ref = x;`	`int* p = &x;`
Null	Cannot be null	Can be null
Rebinding	Cannot rebind	Can rebind
Access	Direct: `ref`	Dereference: `*p`

Structures

intermediate10m

Structures allow us to group related data.

cpp

struct Student
{
    std::string name;
    int age;
    double marks;
};

Create:

cpp

Student s;
s.name = "Ram";
s.age = 20;
s.marks = 85.5;

Initialization

cpp

Student s = {"Ram", 20, 85.5};

Array of Structures

cpp

Student students[3] = {
    {"Ram", 20, 85.5},
    {"Shyam", 21, 90.0},
    {"Hari", 19, 78.0}
};

Introduction to OOP

intermediate15m

Object-Oriented Programming is a way of designing programs around objects that contain data and behavior.

Important Concepts

text

Class
Object
Encapsulation
Inheritance
Polymorphism
Abstraction

Real-World Analogy

text

Class -> Blueprint for a house
Object -> Actual house built from blueprint

Benefits

Code reusability
Data hiding (security)
Easier maintenance
Real-world modeling

Classes

intermediate15m

A class is a blueprint for objects.

cpp

class Student
{
public:
    std::string name;
    int age;
};

Create object:

cpp

Student s1;
s1.name = "Ram";
s1.age = 20;

Access Specifiers

Specifier	Access
`public`	Accessible from anywhere
`private`	Accessible only within class
`protected`	Accessible within class and derived classes

Class vs Object

intermediate10m

Use a real-world analogy.

text

Class
  |
Blueprint

Object
  |
Actual thing created from blueprint

Example:

text

Class -> Student

Objects:
student1 (Ram, 20)
student2 (Shyam, 21)
student3 (Hari, 19)

Constructors

intermediate15m

A constructor is called when an object is created.

Default Constructor

cpp

class Student
{
public:
    Student()
    {
        std::cout << "Student created";
    }
};

Parameterized Constructor

cpp

class Student
{
public:
    std::string name;
    int age;

    Student(std::string n, int a)
    {
        name = n;
        age = a;
    }
};

Create:

cpp

Student s("Ram", 20);

Initializer List (Preferred)

cpp

Student(std::string n, int a) : name(n), age(a) {}

Encapsulation

intermediate10m

Encapsulation means controlling access to an object's data and behavior.

cpp

class BankAccount
{
private:
    double balance;

public:
    void deposit(double amount)
    {
        if (amount > 0)
            balance += amount;
    }

    double getBalance()
    {
        return balance;
    }
};

text

private -> internal data
public  -> controlled interface

Benefits

Data protection
Controlled access
Easy maintenance
Flexibility to change internal implementation

Inheritance

advanced20m

Inheritance allows one class to derive from another.

text

          Person
            |
     ----------------
     |              |
   Student        Teacher

cpp

class Person
{
public:
    std::string name;
};

class Student : public Person
{
public:
    int rollNumber;
};

Usage:

cpp

Student s;
s.name = "Ram";      // Inherited from Person
s.rollNumber = 101;  // Own member

Types of Inheritance

Single
Multiple
Multilevel
Hierarchical
Hybrid

Polymorphism

advanced25m

Polymorphism means: One interface can have different implementations.

Function Overloading

cpp

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

Virtual Functions (Runtime Polymorphism)

cpp

class Animal
{
public:
    virtual void sound()
    {
        std::cout << "Animal sound";
    }
};

class Dog : public Animal
{
public:
    void sound() override
    {
        std::cout << "Bark";
    }
};

cpp

Animal* a = new Dog();
a->sound();  // Output: Bark

Exception Handling

advanced15m

Programs can encounter exceptional situations.

cpp

try
{
    int a = 10;
    int b = 0;

    if (b == 0)
        throw "Division by zero";

    std::cout << a / b;
}
catch (const char* msg)
{
    std::cout << "Error: " << msg;
}

Keywords

Keyword	Purpose
`try`	Block of code that might throw
`catch`	Handles the exception
`throw`	Signals an exception

Standard Exceptions

cpp

#include <stdexcept>

throw std::runtime_error("Something went wrong");

File Handling

advanced15m

Writing to File

cpp

#include <fstream>

std::ofstream file("data.txt");
file << "Hello World";
file.close();

Reading from File

cpp

#include <fstream>

std::ifstream file("data.txt");
std::string text;

while (std::getline(file, text))
{
    std::cout << text << "\n";
}
file.close();

Check if File Exists

cpp

std::ifstream file("data.txt");
if (file.is_open())
{
    // File exists, read it
    file.close();
}

STL

advanced25m

Introduce the Standard Template Library after students understand the basics.

Important Containers

Container	Description
`vector`	Dynamic array
`array`	Fixed-size array
`string`	String class
`map`	Key-value pairs
`set`	Unique sorted elements
`stack`	LIFO
`queue`	FIFO
`priority_queue`	Sorted queue

Important Algorithms

cpp

sort()
find()
reverse()

vector

advanced15m

A vector is a dynamic sequence container.

cpp

#include <vector>

std::vector<int> numbers;

numbers.push_back(10);
numbers.push_back(20);
numbers.push_back(30);

Loop

cpp

for (int number : numbers)
{
    std::cout << number << "\n";
}

Size and Access

cpp

numbers.size();    // 3
numbers[0];        // 10
numbers.at(1);     // 20 (with bounds checking)
numbers.pop_back(); // Remove last element

2D Vector

cpp

std::vector<std::vector<int>> matrix = {
    {1, 2, 3},
    {4, 5, 6},
    {7, 8, 9}
};

Problem-Solving Practice

intermediate30m

Students should solve problems continuously.

Beginner Problems

Problem 1

Input two numbers and calculate sum, difference, product, quotient.

Problem 2

Check whether a number is even or odd.

Problem 3

Find the largest of three numbers.

Problem 4

Calculate student grade.

Problem 5

Calculate factorial.

Problem 6

Check whether a number is prime.

Problem 7

Reverse a number.

Problem 8

Check whether a number is palindrome.

Array Problems

intermediate20m

Students should solve:

Find maximum
Find minimum
Calculate sum
Calculate average
Search for an element
Count even numbers
Count odd numbers
Reverse array
Sort array
Find duplicate values

Example: Find Maximum

cpp

int arr[5] = {23, 55, 2, 67, 12};
int max = arr[0];

for (int i = 1; i < 5; i++)
{
    if (arr[i] > max)
        max = arr[i];
}

std::cout << "Maximum: " << max;

Mini Project Ideas

intermediate15m

After fundamentals, give students small projects.

Project 1 - Student Grade System

Features:

Enter student
Enter marks
Calculate total
Calculate average
Determine grade
Display result

Project 2 - Calculator

Operations: +, -, *, /, %

Project 3 - Number Guessing Game

Computer chooses a number. Student guesses. Program responds: Too high, Too low, Correct.

Project 4 - Student Management System

Store: Student ID, Name, Age, Marks Operations: Add, Display, Search, Update, Delete

Templates Best Practices

C++ Programming LearnModern C++

Modern C++

auto, lambda, smart pointers, move semantics

Course Introduction

beginner5m

Learning Objectives

By the end of this course, students should be able to:

Understand basic programming concepts
Write basic C++ programs
Use variables and data types
Take input and produce output
Use operators and expressions
Make decisions using conditional statements
Repeat operations using loops
Create and use functions
Work with arrays and strings
Understand pointers and references
Understand structures
Understand Object-Oriented Programming
Create classes and objects
Apply inheritance and polymorphism
Work with files
Use the C++ Standard Library
Solve programming problems

What is Programming?

beginner5m

Definition

Programming is the process of writing instructions that tell a computer how to perform a task.

Example Problem

Calculate the average marks of a student.

A human might think:

text

Get marks
Add marks
Divide by number of subjects
Display result

A computer needs these instructions expressed in a programming language.

Program

A program is a set of instructions written to solve a particular problem.

cpp

#include <iostream>

int main()
{
    std::cout << "Hello World!";
    return 0;
}

What is C++?

beginner5m

C++ is a general-purpose, compiled programming language that supports procedural, object-oriented, and generic programming.

Why Learn C++?

Learning programming fundamentals
Data structures and algorithms
Competitive programming
Game development
System software
Embedded systems
High-performance applications
Operating systems
Software engineering

Compiler

beginner10m

A computer does not directly understand normal C++ source code. The source code is processed by a compiler.

text

C++ Source Code
       |
    Compiler
       |
Machine Code
       |
    Program
       |
      CPU

Important Terms

Source Code

Code written by the programmer.

Compiler

Software that translates source code into machine-executable code.

Executable

The resulting program that the computer can execute.

Installing C++

beginner10m

Students need:

C++ compiler
Code editor / IDE
Terminal or build environment

Possible Setups

Visual Studio
VS Code with a C++ compiler
Code::Blocks
Other C++ IDEs
Online C++ compiler

First C++ Program

beginner15m

cpp

#include <iostream>

int main()
{
    std::cout << "Hello World!";
    return 0;
}

Line-by-Line Explanation

Line 1: `#include <iostream>`

This includes the standard input/output library. We need it for std::cout and std::cin.

Line 2: `int main()`

main() is the entry point of a C++ program. Program execution begins from main().

`{ }`

These define a block of code.

`std::cout`

Used to display output.

`return 0`

Indicates that the program finished successfully.

Printing Output

beginner10m

Basic Output

cpp

#include <iostream>

int main()
{
    std::cout << "Hello";
    return 0;
}

Multiple Outputs

cpp

std::cout << "Hello";
std::cout << "World";

Output: HelloWorld

New Line

cpp

std::cout << "Hello\n";
std::cout << "World";

Output:

text

Hello
World

Or:

cpp

std::cout << "Hello" << std::endl;

Multiple Values

cpp

std::cout << "Age: " << 20;

Output: Age: 20

Comments

beginner5m

Comments are ignored by the compiler.

Single-line Comment

cpp

// This is a comment

Multi-line Comment

cpp

/*
   This is
   a multi-line
   comment
*/

Teaching Point: Comments are for humans, not for the computer.

Good Example

cpp

// Calculate total price
double total = price * quantity;

Variables

beginner10m

Definition

A variable is a named location used to store data.

cpp

int age = 20;

Think of it as:

text

age
 |
+------+
|  20  |
+------+

Variable Declaration

cpp

int age;

Assignment

cpp

age = 20;

Declaration + Initialization

cpp

int age = 20;

Data Types

beginner10m

Important Beginner Data Types

Type	Example	Purpose
`int`	`10`	Whole numbers
`float`	`10.5f`	Decimal numbers
`double`	`10.5`	More precise decimals
`char`	`'A'`	Single character
`bool`	`true`	True/false
`std::string`	`"Ram"`	Text

Examples

cpp

int age = 20;
double salary = 50000.50;
char grade = 'A';
bool passed = true;
std::string name = "Ram";

For strings, include #include <string>.

Character vs String

beginner5m

Important Beginner Concept

Character: 'A' (single quotes)

String: "A" (double quotes)

Character uses single quotes.

String uses double quotes.

Example

cpp

char c = 'A';      // Character
std::string s = "A"; // String

Common Mistake: Students often confuse 'A' (char) with "A" (string).

Constants

beginner5m

Sometimes a value should not change.

cpp

const double PI = 3.14159;

After this, PI = 5; is not allowed.

Teaching Example

cpp

const double TAX_RATE = 0.13;

double calculateTax(double amount)
{
    return amount * TAX_RATE;
}

Why constants? They make programs safer and easier to understand. If a value is named and constant, programmers know it won't change accidentally.

Input

beginner10m

Use std::cin.

cpp

int age;

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

std::cout << "You are " << age << " years old.";

Multiple Inputs

cpp

int a, b;

std::cin >> a >> b;

Students can enter: 10 20

Example - Student Information

beginner10m

cpp

#include <iostream>
#include <string>

int main()
{
    std::string name;
    int age;

    std::cout << "Enter your name: ";
    std::cin >> name;

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

    std::cout << "Name: " << name << "\n";
    std::cout << "Age: " << age << "\n";

    return 0;
}

Arithmetic Operators

beginner10m

Operator	Meaning
`+`	Addition
`-`	Subtraction
`*`	Multiplication
`/`	Division
`%`	Modulus

Example

cpp

int a = 10;
int b = 3;

std::cout << a + b;  // 13
std::cout << a - b;  // 7
std::cout << a * b;  // 30
std::cout << a / b;  // 3 (integer division!)
std::cout << a % b;  // 1

Integer Division

beginner5m

Very Important!

cpp

int result = 10 / 3;

Result: 3 (not 3.3333)

Because both operands are integers.

Compare

cpp

double result = 10.0 / 3;

Result: 3.3333

Common Mistake: Students forget that integer division truncates the decimal part.

Assignment Operators

beginner5m

text

=
+=
-=
*=
/=
%=

Example

cpp

int x = 10;
x += 5;  // x is now 15
x -= 3;  // x is now 12
x *= 2;  // x is now 24
x /= 4;  // x is now 6
x %= 4;  // x is now 2

Increment and Decrement

beginner10m

cpp

x++;

Equivalent conceptually to: x = x + 1;

Similarly:

cpp

x--;

means: x = x - 1;

Prefix vs Postfix

cpp

int a = 5;
int b = a++;  // b = 5, a = 6 (postfix: use then increment)
int c = ++a;  // c = 7, a = 7 (prefix: increment then use)

Relational Operators

beginner5m

Used to compare values.

text

>
<
>=
<=
==
!=

Example

cpp

int age = 20;
std::cout << (age >= 18);  // 1 (true)
std::cout << (age < 18);   // 0 (false)

Note: In C++, true is represented as 1 and false as 0 when printed.

= vs ==

beginner5m

Very Important!

cpp

x = 10;    // Assignment: Assign 10 to x
x == 10    // Comparison: Is x equal to 10?

Common Mistake

cpp

if (x = 10)  // WRONG: This assigns 10 to x!
{
    // Always executes because 10 is truthy
}

Correct:

cpp

if (x == 10)  // CORRECT: This checks equality
{
    // Executes only if x is 10
}

Conditional Statements

beginner20m

if

cpp

if (age >= 18)
{
    std::cout << "Adult";
}

if-else

cpp

if (age >= 18)
{
    std::cout << "Adult";
}
else
{
    std::cout << "Minor";
}

else if

cpp

if (marks >= 80)
{
    std::cout << "A";
}
else if (marks >= 60)
{
    std::cout << "B";
}
else if (marks >= 40)
{
    std::cout << "C";
}
else
{
    std::cout << "Fail";
}

Logical Operators

beginner10m

AND (`&&`)

Both conditions must be true.

cpp

if (age >= 18 && age <= 60)
{
    std::cout << "Valid age";
}

OR (`||`)

At least one condition must be true.

cpp

if (day == "Saturday" || day == "Sunday")
{
    std::cout << "Weekend";
}

NOT (`!`)

Reverses a Boolean condition.

cpp

if (!isFinished)
{
    std::cout << "Still running";
}

switch

beginner15m

Useful when comparing one value against multiple fixed choices.

cpp

int choice;
std::cin >> choice;

switch (choice)
{
    case 1:
        std::cout << "Add";
        break;

    case 2:
        std::cout << "Delete";
        break;

    case 3:
        std::cout << "Exit";
        break;

    default:
        std::cout << "Invalid choice";
}

Teaching Point: Explain the purpose of break. Without it, execution "falls through" to the next case.

Loops

beginner15m

Why Loops?

Suppose we need to print:

text

Without a loop:

cpp

std::cout << 1;
std::cout << 2;
std::cout << 3;
std::cout << 4;
std::cout << 5;

With a loop:

cpp

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

for Loop

beginner10m

Syntax

cpp

for (initialization; condition; update)
{
    // statements
}

Example

cpp

for (int i = 1; i <= 10; i++)
{
    std::cout << i << "\n";
}

How a for Loop Executes

beginner10m

For:

cpp

for (int i = 1; i <= 3; i++)

Execution Trace

text

i = 1
 |
condition true (1 <= 3)
 |
execute body
 |
i++
 |
condition true (2 <= 3)
 |
execute body
 |
i++
 |
condition true (3 <= 3)
 |
execute body
 |
i++
 |
condition false (4 <= 3)
 |
stop

while Loop

beginner10m

cpp

int i = 1;

while (i <= 5)
{
    std::cout << i << "\n";
    i++;
}

Use while when repetition depends primarily on a condition.

Example

cpp

int number;
std::cout << "Enter a positive number: ";
std::cin >> number;

while (number < 0)
{
    std::cout << "Invalid! Try again: ";
    std::cin >> number;
}

do-while

beginner10m

cpp

int i = 1;

do
{
    std::cout << i << "\n";
    i++;
}
while (i <= 5);

Important Difference

do-while executes the body at least once.

Example

cpp

int choice;

do
{
    std::cout << "1. Play\n";
    std::cout << "2. Settings\n";
    std::cout << "3. Exit\n";
    std::cout << "Enter choice: ";
    std::cin >> choice;
}
while (choice != 3);

break and continue

beginner10m

break

Stops the loop.

cpp

for (int i = 1; i <= 10; i++)
{
    if (i == 5)
        break;

    std::cout << i << "\n";
}

Output: 1 2 3 4

continue

Skips the current iteration.

cpp

for (int i = 1; i <= 5; i++)
{
    if (i == 3)
        continue;

    std::cout << i << "\n";
}

Output: 1 2 4 5

Functions

intermediate20m

Why Functions?

Functions help:

Organize code
Reuse code
Reduce duplication
Make programs easier to understand
Break large problems into smaller problems

Simple Function

cpp

void greet()
{
    std::cout << "Hello";
}

Call: greet();

Function Parameters

intermediate10m

cpp

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

Call: greet("Ram");

Multiple Parameters

cpp

void add(int a, int b)
{
    std::cout << a + b;
}

Call: add(10, 20);

Return Values

intermediate10m

cpp

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

Usage:

cpp

int result = add(10, 20);
std::cout << result;  // 30

Function That Returns Boolean

cpp

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

Usage:

cpp

if (isEven(4))
{
    std::cout << "Even";
}

Function Structure

intermediate10m

Teach students to identify:

cpp

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

Part	Meaning
`int`	Return type
`add`	Function name
`int a`	Parameter
`int b`	Parameter
`return`	Sends value back

Function Declaration vs Definition

Declaration (prototype):

cpp

int add(int a, int b);

Definition:

cpp

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

Arrays

intermediate15m

An array stores multiple values of the same type.

cpp

int marks[5];

Initialize:

cpp

int marks[5] = {80, 70, 90, 60, 85};

Partial Initialization

cpp

int arr[5] = {10, 20};  // {10, 20, 0, 0, 0}

Zero Initialization

cpp

int arr[5] = {};  // {0, 0, 0, 0, 0}

Array Indexing

intermediate10m

C++ arrays start at index 0.

text

Index:   0   1   2   3   4
         |   |   |   |   |
Marks:  80  70  90  60  85

Therefore: marks[0] is 80.

cpp

std::cout << marks[0];  // 80
std::cout << marks[2];  // 90

Common Mistake: Accessing marks[5] on an array of size 5 is out of bounds!

Arrays + Loops

intermediate15m

cpp

int marks[5] = {80, 70, 90, 60, 85};

for (int i = 0; i < 5; i++)
{
    std::cout << marks[i] << "\n";
}

This is an important point where students begin combining concepts.

Finding Maximum

cpp

int marks[5] = {80, 70, 90, 60, 85};
int max = marks[0];

for (int i = 1; i < 5; i++)
{
    if (marks[i] > max)
    {
        max = marks[i];
    }
}

std::cout << "Maximum: " << max;

Strings

intermediate10m

cpp

std::string name = "Abhay";

Useful Operations

cpp

name.length();     // 5
name.empty();      // false

Concatenation

cpp

std::string first = "Hello ";
std::string second = "World";
std::string result = first + second;  // "Hello World"

Accessing Characters

cpp

std::string name = "Hello";
std::cout << name[0];  // H
std::cout << name[4];  // o

getline()

intermediate10m

Difference

cpp

std::cin >> name;

Reads one whitespace-delimited value.

cpp

std::getline(std::cin, name);

Reads a complete line.

Example

cpp

std::string fullName;

std::cout << "Enter your full name: ";
std::getline(std::cin, fullName);

std::cout << "Hello, " << fullName;

Pointers

intermediate25m

Introduce pointers only after students understand variables.

A pointer stores an address.

cpp

int x = 10;
int* p = &x;

Here:

text

x  -> value
&x -> address
p  -> address stored in pointer
*p -> value at that address

Key Operators

Operator	Meaning
`&`	Address-of
`*`	Dereference

Pointer Example

intermediate15m

cpp

int x = 10;
int* p = &x;

std::cout << x << "\n";    // 10
std::cout << &x << "\n";   // address of x
std::cout << p << "\n";    // same address
std::cout << *p << "\n";   // 10 (dereference)

Modifying via Pointer

cpp

int x = 10;
int* p = &x;

*p = 20;  // Change value at address

std::cout << x;  // 20

References

intermediate15m

cpp

int x = 10;
int& ref = x;

ref becomes another name for x.

cpp

ref = 20;
std::cout << x;  // 20

References vs Pointers

Feature	Reference	Pointer
Syntax	`int& ref = x;`	`int* p = &x;`
Null	Cannot be null	Can be null
Rebinding	Cannot rebind	Can rebind
Access	Direct: `ref`	Dereference: `*p`

Structures

intermediate10m

Structures allow us to group related data.

cpp

struct Student
{
    std::string name;
    int age;
    double marks;
};

Create:

cpp

Student s;
s.name = "Ram";
s.age = 20;
s.marks = 85.5;

Initialization

cpp

Student s = {"Ram", 20, 85.5};

Array of Structures

cpp

Student students[3] = {
    {"Ram", 20, 85.5},
    {"Shyam", 21, 90.0},
    {"Hari", 19, 78.0}
};

Introduction to OOP

intermediate15m

Object-Oriented Programming is a way of designing programs around objects that contain data and behavior.

Important Concepts

text

Class
Object
Encapsulation
Inheritance
Polymorphism
Abstraction

Real-World Analogy

text

Class -> Blueprint for a house
Object -> Actual house built from blueprint

Benefits

Code reusability
Data hiding (security)
Easier maintenance
Real-world modeling

Classes

intermediate15m

A class is a blueprint for objects.

cpp

class Student
{
public:
    std::string name;
    int age;
};

Create object:

cpp

Student s1;
s1.name = "Ram";
s1.age = 20;

Access Specifiers

Specifier	Access
`public`	Accessible from anywhere
`private`	Accessible only within class
`protected`	Accessible within class and derived classes

Class vs Object

intermediate10m

Use a real-world analogy.

text

Class
  |
Blueprint

Object
  |
Actual thing created from blueprint

Example:

text

Class -> Student

Objects:
student1 (Ram, 20)
student2 (Shyam, 21)
student3 (Hari, 19)

Constructors

intermediate15m

A constructor is called when an object is created.

Default Constructor

cpp

class Student
{
public:
    Student()
    {
        std::cout << "Student created";
    }
};

Parameterized Constructor

cpp

class Student
{
public:
    std::string name;
    int age;

    Student(std::string n, int a)
    {
        name = n;
        age = a;
    }
};

Create:

cpp

Student s("Ram", 20);

Initializer List (Preferred)

cpp

Student(std::string n, int a) : name(n), age(a) {}

Encapsulation

intermediate10m

Encapsulation means controlling access to an object's data and behavior.

cpp

class BankAccount
{
private:
    double balance;

public:
    void deposit(double amount)
    {
        if (amount > 0)
            balance += amount;
    }

    double getBalance()
    {
        return balance;
    }
};

text

private -> internal data
public  -> controlled interface

Benefits

Data protection
Controlled access
Easy maintenance
Flexibility to change internal implementation

Inheritance

advanced20m

Inheritance allows one class to derive from another.

text

          Person
            |
     ----------------
     |              |
   Student        Teacher

cpp

class Person
{
public:
    std::string name;
};

class Student : public Person
{
public:
    int rollNumber;
};

Usage:

cpp

Student s;
s.name = "Ram";      // Inherited from Person
s.rollNumber = 101;  // Own member

Types of Inheritance

Single
Multiple
Multilevel
Hierarchical
Hybrid

Polymorphism

advanced25m

Polymorphism means: One interface can have different implementations.

Function Overloading

cpp

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

Virtual Functions (Runtime Polymorphism)

cpp

class Animal
{
public:
    virtual void sound()
    {
        std::cout << "Animal sound";
    }
};

class Dog : public Animal
{
public:
    void sound() override
    {
        std::cout << "Bark";
    }
};

cpp

Animal* a = new Dog();
a->sound();  // Output: Bark

Exception Handling

advanced15m

Programs can encounter exceptional situations.

cpp

try
{
    int a = 10;
    int b = 0;

    if (b == 0)
        throw "Division by zero";

    std::cout << a / b;
}
catch (const char* msg)
{
    std::cout << "Error: " << msg;
}

Keywords

Keyword	Purpose
`try`	Block of code that might throw
`catch`	Handles the exception
`throw`	Signals an exception

Standard Exceptions

cpp

#include <stdexcept>

throw std::runtime_error("Something went wrong");

File Handling

advanced15m

Writing to File

cpp

#include <fstream>

std::ofstream file("data.txt");
file << "Hello World";
file.close();

Reading from File

cpp

#include <fstream>

std::ifstream file("data.txt");
std::string text;

while (std::getline(file, text))
{
    std::cout << text << "\n";
}
file.close();

Check if File Exists

cpp

std::ifstream file("data.txt");
if (file.is_open())
{
    // File exists, read it
    file.close();
}

STL

advanced25m

Introduce the Standard Template Library after students understand the basics.

Important Containers

Container	Description
`vector`	Dynamic array
`array`	Fixed-size array
`string`	String class
`map`	Key-value pairs
`set`	Unique sorted elements
`stack`	LIFO
`queue`	FIFO
`priority_queue`	Sorted queue

Important Algorithms

cpp

sort()
find()
reverse()

vector

advanced15m

A vector is a dynamic sequence container.

cpp

#include <vector>

std::vector<int> numbers;

numbers.push_back(10);
numbers.push_back(20);
numbers.push_back(30);

Loop

cpp

for (int number : numbers)
{
    std::cout << number << "\n";
}

Size and Access

cpp

numbers.size();    // 3
numbers[0];        // 10
numbers.at(1);     // 20 (with bounds checking)
numbers.pop_back(); // Remove last element

2D Vector

cpp

std::vector<std::vector<int>> matrix = {
    {1, 2, 3},
    {4, 5, 6},
    {7, 8, 9}
};

Problem-Solving Practice

intermediate30m

Students should solve problems continuously.

Beginner Problems

Problem 1

Input two numbers and calculate sum, difference, product, quotient.

Problem 2

Check whether a number is even or odd.

Problem 3

Find the largest of three numbers.

Problem 4

Calculate student grade.

Problem 5

Calculate factorial.

Problem 6

Check whether a number is prime.

Problem 7

Reverse a number.

Problem 8

Check whether a number is palindrome.

Array Problems

intermediate20m

Students should solve:

Find maximum
Find minimum
Calculate sum
Calculate average
Search for an element
Count even numbers
Count odd numbers
Reverse array
Sort array
Find duplicate values

Example: Find Maximum

cpp

int arr[5] = {23, 55, 2, 67, 12};
int max = arr[0];

for (int i = 1; i < 5; i++)
{
    if (arr[i] > max)
        max = arr[i];
}

std::cout << "Maximum: " << max;

Mini Project Ideas

intermediate15m

After fundamentals, give students small projects.

Project 1 - Student Grade System

Features:

Enter student
Enter marks
Calculate total
Calculate average
Determine grade
Display result

Project 2 - Calculator

Operations: +, -, *, /, %

Project 3 - Number Guessing Game

Computer chooses a number. Student guesses. Program responds: Too high, Too low, Correct.

Project 4 - Student Management System

Store: Student ID, Name, Age, Marks Operations: Add, Display, Search, Update, Delete

Templates Best Practices

Modern C++

Course Introduction

Learning Objectives

What is Programming?

Definition

Example Problem

Program

What is C++?

Why Learn C++?

Compiler

Important Terms

Source Code

Compiler

Executable

Installing C++

Possible Setups

First C++ Program

Line-by-Line Explanation

Line 1: #include <iostream>

Line 2: int main()

{ }

std::cout

return 0

Printing Output

Basic Output

Multiple Outputs

New Line

Multiple Values

Comments

Single-line Comment

Multi-line Comment

Good Example

Variables

Definition

Variable Declaration

Assignment

Declaration + Initialization

Data Types

Important Beginner Data Types

Examples

Character vs String

Important Beginner Concept

Example

Constants

Teaching Example

Input

Multiple Inputs

Example - Student Information

Arithmetic Operators

Example

Integer Division

Very Important!

Compare

Assignment Operators

Example

Increment and Decrement

Prefix vs Postfix

Relational Operators

Example

= vs ==

Very Important!

Common Mistake

Conditional Statements

if

if-else

else if

Logical Operators

AND (&&)

OR (||)

NOT (!)

switch

Loops

Why Loops?

for Loop

Syntax

Example

How a for Loop Executes

Execution Trace

while Loop

Example

Line 1: `#include <iostream>`

Line 2: `int main()`

`{ }`

`std::cout`

`return 0`

AND (`&&`)

OR (`||`)

NOT (`!`)