What does '#include <stdio.h>' really do in a C program

c include stdio
yaylitzis picture yaylitzis · Sep 30, 2013 · Viewed 72.1k times · Source

I am new to c programming and I was coding some simple programs "Hello world" style.

In all of these programs I put #include<stdio.h> in the top but I am not sure what this means exactly. I googled it and I found that stdio.h is a file that has commands for the preprocessor, but what is a preprocessor? I thought when I write code, I compile it and my code transforms to a form that a "computer" can read and then I can run it. Can somebody explain to me what the usage of this command is?

Answer

user267885 picture user267885 · Sep 30, 2013

It looks for the stdio.h file and effectively copy-pastes it in the place of this #include statements. This file contains so-called function prototypes of functions such as printf(), scanf(), ... so that compiler knows what are their parameters and return values.

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