Introduction to Programming & Modern C++

What you'll learn

C++ combines direct control over native resources with high-level abstractions that can be both expressive and efficient. In this lesson, you'll establish the modern mental model, install a C++20 toolchain, and compile your first native program.

By the end, you'll be able to:

• Explain what Modern C++ is and how it relates to—but differs from—C
• Describe preprocessing, compilation, linking, and execution
• Compile a warning-clean C++20 program with GCC or Clang
• Read the essential structure of a small C++ source file

What is Modern C++?

C++ is a general-purpose compiled language designed for software where performance, predictable resource use, portability, and rich abstraction all matter. It supports procedural, object-oriented, generic, functional, and low-level programming styles.

C++ grew from C and retains substantial compatibility, but it is its own language. Modern C++ code normally favors std::string, containers, algorithms, value types, and scope-bound resource owners over raw arrays and manual allocation.

Modern C++ principles

This course uses C++20 as its baseline. Later lessons identify selected C++23 facilities. Selecting a standard matters because the compiler should reject accidental reliance on unavailable language or library features.

Where C++ is used

C++ is strongest when an application needs control over latency, memory, hardware, or a large cross-platform native codebase while still benefiting from reusable abstractions.

How source becomes a program

A .cpp file is human-readable source. A toolchain translates it into machine instructions and combines it with the standard library and your other compiled files.

1. The preprocessor handles directives such as #include.
2. The compiler checks types and translates one translation unit.
3. The assembler emits an object file containing native code.
4. The linker resolves names across object files and libraries.
5. The operating system loads and executes the resulting program.

Compiler & editor setup

Install a current GCC, Clang, or Microsoft Visual C++ toolchain. On Windows, Visual Studio, LLVM, MSYS2, or WSL are common choices. macOS provides Clang through Xcode Command Line Tools; Linux distributions provide GCC and Clang through their package managers.

g++ --version
clang++ --version

# In a Visual Studio Developer Command Prompt:
cl

Use an editor with C++ diagnostics and navigation—VS Code, Visual Studio, CLion, or another capable editor—but learn the terminal command too. It makes the real inputs to the compiler visible.

Your first program: Hello, World!

Create main.cpp and enter the following program:

#include <iostream>

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

# GCC
g++ -std=c++20 -Wall -Wextra -Wpedantic main.cpp -o hello
./hello

# Clang uses the same core options
clang++ -std=c++20 -Wall -Wextra -Wpedantic main.cpp -o hello

Anatomy of a C++ program

• #include <iostream> makes standard stream declarations available.
• int main() defines the program's entry point.
• std::cout is the standard character-output stream.
• << inserts a value into an output stream.
• \n writes a newline without forcing an unnecessary flush.
• return 0; reports successful completion to the environment.

Development workflow

1. Edit one small, understandable change
2. Compile with the selected standard and strict warnings
3. Fix the first diagnostic before interpreting later cascaded errors
4. Run normal, boundary, and invalid-input cases
5. Save a working checkpoint in version control

A diagnostic normally includes a file, line, column, severity, and explanation. Read the exact source location and nearby context; one missing quote, brace, or semicolon can cause several later messages.

Comments

C++ supports line and block comments. Prefer clear names and small functions; use comments to preserve intent, constraints, units, ownership, or a non-obvious design decision.

#include <iostream>

int main() {
    // Explain intent or a constraint—not obvious punctuation.
    std::cout << "C++ rewards clear ownership.\n";

    /* Block comments can span several lines,
       but they do not nest. */
    return 0;
}

Recap & quick check

Your Modern C++ toolchain is ready. Next: Module 2 — Variables, Fundamental Types & Operators, where programs begin representing and transforming real values.