Question

I want to create a header file in C and add it to a library. How do I create the header file and add/access it to/from the library.

Answer 1

Some header:

//header.h
#ifndef HEADER_H
#define HEADER_H

int ThisReturnsOne() {
    return 1;
}

#endif //HEADER_H

Some c file:

//file.c
#include "header.h"

int main() {
    int x;
    x = ThisReturnsOne(); //x == 1
}

So the contents of “header.h” are available to “file.c”. This assumes they are in the same directory.

Edit: Added include guards. This prevents the header file from being included in the same translation unit twice.