Compilation process of a C program -GET EDUCATE

Contents

Introduction to Problem Solving

⯈Elementary Problems

Basics of C Programming

⯈Basic C Programs

Compilation process of a C Program

Compilation is a process of converting high level programming to machine level language.

The compiler goes through the following steps to convert it to the machine code or object code.

You may watch the video at the end of this page.

The source file is written with the .c extension.
This file is in high level language and cannot be understood by the machine, so needs to convert to low level language.

This is the first pass of the compiler.
The pre-processor removes:
- comments.
- expansion of the included files.
- expands the MACROS or mainfest constants.
- conditional compilation.
The pre-processor creates the .i file.

In this step the .i file is compiled to the .s file
The .s file is created with the filename of test.s (since test is the C file that we have created)

In this step the .s file is converted to the .o (object file)
The object file is the one which the machine understands, and we execute the object file.

The linker links all the function calls. If any function definition is missing or there is a mismatch, then the linker reports an error.

We write the program using the editor. Let us use the gedit editor.

gedit test.c

We write the program in the file,

#include<stdio.h>
int main()
{
    printf("Welcome to geteducate.org\n");
    return 0;
}

To convert this file (test.c) to machine language we use compiler, gcc and we compile file as,

gcc test.c

By default, it creates an object file with name a.out

To execute the object file we write,

./a.out

We can change the name of the object file using -o option of gcc.

gcc test.c -o test

Creates an object file with name test instead of a.out

To execute,

./test

Note:

We execute the .o file not the .c file
Hence any modifications in .c file has to be recompiled to overwrite the .o file