Introduction to C & Setup

Duration: 45 min

C is a powerful, low-level programming language created by Dennis Ritchie in 1972. It remains one of the most influential languages in computer science, forming the foundation for Unix, Linux, and countless modern systems. In this module, you'll learn C's history, set up your development environment, and write your first program.

History & Why C Matters

C revolutionized programming by providing a balance between high-level abstraction and low-level hardware control. It's used in operating systems, embedded systems, databases, and performance-critical applications. Understanding C teaches you how computers actually work.

Setting Up Your Environment

On macOS

// Install Xcode Command Line Tools
// Open Terminal and run:
// xcode-select --install

// Verify gcc is installed
gcc --version

On Linux (Ubuntu/Debian)

// Install gcc and build tools
// sudo apt-get update
// sudo apt-get install build-essential

// Verify installation
gcc --version

On Windows

// Download MinGW from mingw-w64.org
// Add to PATH
// Verify: gcc --version

Your First Program: Hello World

#include <stdio.h>

int main() {
    printf("Hello, World!\n");
    return 0;
}

Save this as hello.c and compile:

// gcc hello.c -o hello
// ./hello
// Output: Hello, World!

Understanding the Compilation Process

// Source code (hello.c) → Preprocessor → Compiler → Assembler → Linker → Executable

// Step 1: Preprocessing (handles #include, #define)
// gcc -E hello.c

// Step 2: Compilation (converts to assembly)
// gcc -S hello.c

// Step 3: Assembly (converts to object code)
// gcc -c hello.c

// Step 4: Linking (creates executable)
// gcc hello.o -o hello

Common GCC Flags

// gcc -Wall hello.c -o hello        // Enable all warnings
// gcc -g hello.c -o hello           // Include debug symbols
// gcc -O2 hello.c -o hello          // Optimize for speed
// gcc -std=c99 hello.c -o hello     // Use C99 standard

Program Structure

#include <stdio.h>      // Include standard I/O library

int main() {            // Entry point of program
    // Your code here
    return 0;           // Return 0 to indicate success
}

Quiz 1: C History

Quiz 2: Compilation

Quiz 3: Hello World

Quiz 4: GCC Flags

Quiz 5: Return Value