The Compilation Process of C Language

Learn how C code is converted into machine code that can be executed by a computer.

Ishan Hansaka Silva

Published in

LinkIT

2 min readSep 5, 2023

What is compilation?

Compilation is the process the computer takes to transform a program written in a high-level language from source code into machine code that the computer can understand.

Source code

Sour code which appears in a human-readable text format includes instructions that guide the program’s execution.

An example of printing Hello World

#include<stdio.h>
int main()
{
  printf("Hello World"):
  return 0;
}

4 stages of the compilation process

Stage 1 — Preprocessing

The preprocessor is a program that is used to process source code before it is compiled. It performs several tasks, including:

Removing comments
Expanding macros
Including files
Converting source code to expanded code.

Output file: hello.i

Stage 2 — Compiling

The C compiler checks for valid syntax in C language. If any wrong syntax is found, the compiler reports that error. After the expanded code has been syntactically verified, the compiler converts it into assembly code.

Output file: hello.s

Stage 3 — Assembling

In this stage, the assembler converts assembly code into pure binary code or machine code known as the object code.

Output file: hello.o

Stage 4 — Linking

The linker merges all the object code from multiple modules and libraries into a single file and produces the final executable file.

Output file: hello.exe