Introduction to C++ & Your First Program

What Is C++?

C++ is a compiled, statically-typed, general-purpose programming language. It was created by Bjarne Stroustrup starting in 1979 at Bell Labs, originally as an extension of the C language called "C with Classes." The name was changed to C++ in 1983 — the ++ is a nod to C's own increment operator, meaning "one step beyond C."

C++ gives you two things that many modern languages trade away for convenience: direct control over memory and hardware, and compiled performance close to the metal. That combination is exactly why it's still the language of choice whenever raw speed and predictable resource usage matter.

Where C++ Is Used

C++ shows up wherever a program needs to run fast, use memory efficiently, and talk closely to hardware or an operating system. That's a wide net — from the engine rendering a video game frame to the firmware inside a microcontroller.

Compiled vs. Interpreted — C++ vs. Python

If you've come from BitWithBite's Python course, this is the biggest mental shift you'll make. Python is interpreted — the Python interpreter reads your .py file and executes it line by line, on the spot. C++ is compiled — a separate program (the compiler) translates your entire .cpp file into a standalone machine-code executable before anything runs.

Installing a C++ Compiler

To turn C++ source code into a runnable program, you need a compiler. The two most common ones are g++ (part of the GNU Compiler Collection) and clang++ (the LLVM project's compiler). Either is a fine choice for this course.

🪟 Windows

🍎 macOS

🐧 Linux

# Update package list
sudo apt update

# Install the GNU C++ compiler
sudo apt install g++

# Verify installation
g++ --version

🌐 No installation? Use an online compiler

If you just want to try code snippets without installing anything yet, any browser-based C++ compiler works fine for following along with this course — you type code, click run, and see output immediately. You'll still want a real local compiler once you start building larger programs.

Your First C++ Program — Hello, World!

Every C++ program starts life as a .cpp text file. Let's write the classic first program and then compile and run it.

// hello.cpp
// My first C++ program

#include <iostream>

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

Line by line

Compiling and running hello.cpp

Save the file, open a terminal in the same folder, and run these two commands:

# Step 1: compile hello.cpp into an executable named "hello"
g++ hello.cpp -o hello

# Step 2: run the executable
./hello        # macOS / Linux
hello.exe       # Windows

# Output:
# Hello, World!

A Second Program — Reinforcing Compile & Run

Let's extend the pattern: print a few lines, then do a tiny calculation and print its result too.

// welcome.cpp
// Prints a short welcome, then adds two numbers

#include <iostream>

int main() {
    std::cout << "Hello, World!" << std::endl;
    std::cout << "Welcome to C++." << std::endl;

    int a = 7;
    int b = 5;
    std::cout << "7 + 5 = " << (a + b) << std::endl;

    return 0;
}

Compiling this works exactly the same way: g++ welcome.cpp -o welcome, then ./welcome. The output prints three lines — the two greetings, then 7 + 5 = 12. Notice that a and b are declared with a type (int) before they're used — you'll dig deeper into this in Lesson 2.

Lesson Summary

Let's recap everything you learned in this lesson: