Introduction to C++

What is C++?

C++ is a general-purpose programming language developed by Bjarne Stroustrup at Bell Labs starting in 1979. It is an extension of the C programming language with object-oriented programming capabilities.

High Performance

C++ compiles to machine code, providing excellent runtime performance

Object-Oriented

Supports classes, objects, inheritance, and polymorphism

Memory Control

Direct memory management with pointers and references

Standard Library

Rich STL with containers, algorithms, and utilities

Your First C++ Program

Let's start with the traditional "Hello, World!" program:

Hello World Program

#include <iostream>
using namespace std;

int main() {
    cout << "Hello, World!" << endl;
    return 0;
}

Code Explanation:

#include <iostream> - Includes the input/output stream library
using namespace std; - Allows us to use standard library functions without std:: prefix
int main() - The main function where program execution begins
cout - Character output stream for printing to console
return 0; - Indicates successful program termination

Basic Input and Output

C++ uses streams for input and output operations:

Input and Output Example

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

int main() {
    string name;
    int age;
    
    // Output
    cout << "Enter your name: ";
    
    // Input
    getline(cin, name);  // Read entire line including spaces
    
    cout << "Enter your age: ";
    cin >> age;  // Read integer
    
    // Output with variables
    cout << "Hello, " << name << "!" << endl;
    cout << "You are " << age << " years old." << endl;
    
    return 0;
}

Comments

Comments help document your code and are ignored by the compiler:

Comment Types

#include <iostream>
using namespace std;

/*
 * This is a multi-line comment
 * Used for longer explanations
 * Author: Your Name
 * Date: Today
 */

int main() {
    // This is a single-line comment
    cout << "Hello, World!" << endl;  // Comment at end of line
    
    /* 
       Multi-line comment can also be 
       used inline like this 
    */
    cout << "Learning C++!" << endl;
    
    return 0;  // Program ends successfully
}

Compilation Process

C++ is a compiled language. Here's how to compile and run your programs:

Step 1: Write Code

Create a .cpp file (e.g., hello.cpp)

Step 2: Compile

Use g++ compiler: g++ -o hello hello.cpp

Step 3: Run

Execute: ./hello (Linux/Mac) or hello.exe (Windows)

Common Beginner Mistakes

Missing Semicolons

Every statement in C++ must end with a semicolon ;

Case Sensitivity

C++ is case-sensitive: cout ≠ Cout ≠ COUT

Missing Headers

Don't forget to #include necessary headers

Unmatched Braces

Every opening brace { must have a closing brace }