C Basics

C is a compiled, statically-typed language from 1972 that still powers operating systems, databases, and language runtimes today. Learning C means learning how a computer actually works, no hidden garbage collector, no implicit conversions you didn't ask for, just you and the machine.

Your first program

#include <stdio.h>

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

• #include <stdio.h> pulls in the standard I/O library, so printf exists.
• int main(void) is the entry point every C program starts from, it returns an int exit code to the operating system, 0 means "success".
• printf formats and prints text, \n is a newline escape sequence, unlike Python there's no automatic newline after a print.

Compiling and running

C is compiled ahead of time, there's no interpreter:

gcc hello.c -o hello
./hello

gcc translates your .c source file into a native executable, -o hello names the output file. Every time you change the source, you recompile before running again.

Variables and types

Unlike Python or JavaScript, every variable in C has a fixed, explicit type:

int xp = 0;
float ratio = 0.5f;
char grade = 'A';
xp += 10;

There's no var/let inference, you declare the type up front and it never changes. This is why C is fast, the compiler knows exactly how much memory each variable needs and never has to check types at runtime.