Introduction to C & How Compilation Works

C is not just history — it still powers operating system kernels (including Linux and parts of Windows), embedded devices, microcontrollers, database engines, and performance-critical software. C gives you direct, low-level control over memory, which teaches you how computers actually work under the hood — something higher-level languages deliberately hide from you.

Unlike Python, which is interpreted line-by-line while it runs, C is a compiled language. Before your program can run, a compiler translates your entire C source code into machine code — raw instructions the CPU can execute directly. This extra compilation step is why C programs typically run much faster than interpreted ones, at the cost of needing to be recompiled every time you change the code.

Turning a .c file into a runnable program involves four distinct stages:

1. Preprocessing — handles lines starting with #, like #include and #define, before real compilation begins
2. Compilation — translates your C code into assembly language
3. Assembly — converts assembly into machine code, producing an object file
4. Linking — combines your object file with any needed libraries into one final, executable program

Our Compiler runs all four of these steps automatically the moment you click Run.

#include <stdio.h>

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

#include <stdio.h> pulls in the Standard Input/Output library so you can use printf(). Every C program needs a main() function — this is where execution always begins. return 0; tells the operating system the program finished successfully.

#include <stdio.h>

int main() {
    printf("Hello, my name is Claude!\n");
    printf("I am learning the C language.\n");
    return 0;
}