GCC Include Files Path

GCC looks in several different places for headers.

On a normal Unix system, if you do not instruct it otherwise, it will look for headers requested with #include <file> in:

/usr/local/include

libdir/gcc/target/version/include
/usr/target/include

/usr/include

You can add to this list with the -Idir command line option.

Below is a small demo

///////////     defines.c   ////////

#include <stdio.h>

#include <defines.h>

int main()

begin

    printf("hellon");

    return 0;

end

This requires the folowing header file

///////     headers/defines.h   ///////////

#define begin {

#define end }

//////  save this file in directory named headers

Compile defines.c as below

[raja@AGRAJA ~] gcc defines.c -Iheaders