C++ Introduction

Theory

C++ is a powerful, high-performance programming language developed by Bjarne Stroustrup in 1985 as an extension of the C language. It combines the efficiency and low-level control of C with high-level abstractions like classes, templates, and the Standard Template Library (STL).

C vs C++

| Feature | C | C++ | |---------|---|-----| | Paradigm | Procedural | Multi-paradigm (procedural, OOP, generic) | | Classes | No | Yes | | Inheritance | No | Yes | | Polymorphism | No | Yes | | Templates | No | Yes | | Standard Library | Limited | Rich (STL) | | String handling | Arrays of char | std::string class | | I/O | printf/scanf | std::cin/std::cout |

The key takeaway: C++ is a superset of C — almost all valid C programs are valid C++ programs. But C++ adds object-oriented programming, templates, exceptions, and a rich standard library.

Setting Up a Compiler (G++)

On Linux, install G++ via the package manager:

On macOS, install Xcode Command Line Tools:

xcode-select --install

On Windows, install MinGW or use WSL.

Basic C++ Program

Every C++ program has at least one function — main() — which is the entry point:

Compilation Process

Source Code (.cpp)
    ↓ Preprocessor (#include, #define)
Expanded Source
    ↓ Compiler (g++)
Assembly Code (.s)
    ↓ Assembler
Object Code (.o)
    ↓ Linker (links libraries)
Executable

To compile and run:

The iostream Library and using namespace

#include <iostream> provides input/output functionality:

#include <iostream>
 
// Option 1: Use std:: prefix
std::cout << "Hello" << std::endl;
 
// Option 2: Using directive
using namespace std;
cout << "Hello" << endl;
 
// Option 3: Using specific names (recommended)
using std::cout;
using std::endl;
cout << "Hello" << endl;

cout and cin

cout (console output) uses the insertion operator <<:

int age = 25;
cout << "I am " << age << " years old." << endl;

cin (console input) uses the extraction operator >>:

string name;
int age;
cout << "Enter name: ";
cin >> name;
cout << "Enter age: ";
cin >> age;

Comments

// Single-line comment
 
/*
   Multi-line comment
   spanning multiple lines
*/
 
/**
 * Javadoc-style comment
 * Used for documentation
 */

Basic Syntax Rules

• Statements end with a semicolon ;
• Code blocks use curly braces { }
• C++ is case-sensitive (myVar ≠ MyVar)
• Identifiers can contain letters, digits, and underscores
• Reserved keywords cannot be used as identifiers (int, class, if, etc.)

Function Overloading (Preview)

C++ allows multiple functions with the same name but different parameters:

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

Practical Examples

Exercises

Hello, Alice! You are 25 years old. Your favorite number is 42.

Enter C or F, then the temperature. Example: F 100 → 100°C = 212°F

Sum: 30

Mini Quiz

Mini Project