Including a header file from another directory

Question

I have a main directory A with two sub directories B and C.

Directory B contains a header file structures.c

Answer 1

If you work on a Makefile project or simply run your code from command line, use

gcc -IC main.c

where -I option adds your C directory to the list of directories to be searched for header files, so you'll be able to use #include "structures.h"anywhere in your project.

Answer 2

write

#include "../b/structure.h"

in place of

#include <structures.h>

then go in directory in c & compile your main.c with

gcc main.c

Answer 3

If you want to use the command line argument then you can give gcc -idirafter ../b/ main.c

then you don't have to do any thing inside your program.

Answer 4

When referencing to header files relative to your c file you should use #include "path/to/header.h"

The form #include <someheader.h> is only used for internal headers or for explicitly added directories (in gcc with the -I option).