What is C++? Introduction and Overview

What is C++?

C++ is a general-purpose, compiled, statically-typed programming language created by Bjarne Stroustrup in 1979 at Bell Labs as an extension of C. Originally called "C with Classes", it was renamed to C++ in 1983 — the ++ being C's increment operator, symbolising an improvement over C.

C++ combines low-level memory control with high-level abstractions (OOP, templates, STL). It powers operating systems, game engines, browsers, databases, and embedded systems — anywhere performance and control matter.

History of C++

Features of C++

• Object-Oriented Programming — classes, objects, inheritance, polymorphism, encapsulation, abstraction.
• Generic Programming — templates let you write type-independent code; the entire STL is built on this.
• Low-level Memory Control — direct pointer manipulation, new/delete, and smart pointers.
• High Performance — compiled to native machine code; zero-cost abstractions mean you only pay for what you use.
• Standard Template Library (STL) — ready-made containers (vector, map, set), algorithms (sort, find), and iterators.
• Multi-paradigm — supports procedural, object-oriented, generic, and functional programming styles.
• Portability — compiles on Windows, Linux, macOS, and embedded platforms.
• RAII — Resource Acquisition Is Initialization: resources are tied to object lifetimes, preventing leaks automatically.
• Exception Handling — structured error handling with try/catch/throw.
• Operator Overloading — define custom behaviour for operators like +, -, ==, << on your own types.

C++ vs C — Key Differences

Structure of a C++ Program

Every C++ program follows a predictable structure. Understanding each part is essential before writing any code.

// 1. Preprocessor directive — includes the iostream header
#include <iostream>

// 2. Using declaration — avoids writing std:: prefix everywhere
using namespace std;

// 3. main() — entry point of every C++ program
//    int return type: 0 = success, non-zero = error
int main() {

    // 4. cout — standard output stream
    //    <<  — stream insertion operator
    //    endl — newline + flush buffer (\n is faster)
    cout << "Hello, World!" << endl;

    // 5. Variables — must declare type before use
    int    age    = 25;
    double salary = 55000.50;
    string name   = "Alice";

    cout << name << " is " << age << " years old." << endl;

    // 6. return 0 — signals successful program termination
    return 0;
}

/*
 * Output:
 * Hello, World!
 * Alice is 25 years old.
 */

// A C++ program with a class — the OOP way
#include <iostream>
#include <string>
using namespace std;

// Class definition — blueprint for objects
class Car {
private:                    // only accessible inside the class
    string brand;
    int    year;

public:                     // accessible from outside
    // Constructor — called when object is created
    Car(string brand, int year) : brand(brand), year(year) {}

    // Member function (method)
    void display() const {
        cout << year << " " << brand << endl;
    }
};

int main() {
    Car c1("Toyota", 2022);   // create object on stack
    Car c2("BMW",    2024);

    c1.display();   // 2022 Toyota
    c2.display();   // 2024 BMW

    return 0;
}

C++ Compilation Model

Unlike interpreted languages (Python, JavaScript), C++ is compiled — source code is translated to machine code before running. The process has four stages:

# Compile
g++ hello.cpp -o hello

# Compile with C++17 standard and all warnings (recommended)
g++ -std=c++17 -Wall -Wextra hello.cpp -o hello

# Run on Linux/macOS
./hello

# Run on Windows
hello.exe

# See each compilation stage
g++ -E hello.cpp -o hello.i    # preprocessing only
g++ -S hello.cpp -o hello.s    # compile to assembly
g++ -c hello.cpp -o hello.o    # compile to object file
g++ hello.o -o hello           # link to executable

Applications of C++