2. Introduction to C Programming

Learn the core features of C, write your first program, and understand the compilation pipeline.

C is a small, fast, portable systems programming language that powers operating systems, databases, and embedded devices.

Features of C

• Small core language with powerful composition
• Close to hardware, predictable performance
• Portable across architectures

C standards

• ANSI C (C89/C90), C99, C11 (and later like C17)
• We’ll use -std=c11 for examples

Your first C program

To build via make:

• make hello_world

To run:

• ./bin/hello_world

The compilation pipeline

1. Preprocessor expands macros and includes headers
2. Compiler turns C into assembly/object code
3. Assembler produces .o files
4. Linker combines objects and libraries into an executable
5. Loader maps the program into memory to run

Examples

Hello World (hello_world.c)

Your very first C program – prints a message to the console:

#include <stdio.h>

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

Add Two Numbers (add_two_numbers.c)

A simple program that demonstrates functions, return values, and printf formatting:

#include <stdio.h>

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

int main(void) {
    printf("add(3,4) = %d\n", add(3,4));
    return 0;
}