debian man page for make_relative_filename

make_relative_filename(3alleg4) 				  Allegro manual				   make_relative_filename(3alleg4)

NAME
       make_relative_filename - Tries to make a relative filename from absolute path and filename. Allegro game programming library.

SYNOPSIS
       #include <allegro.h>

       char *make_relative_filename(char *dest, const char *path, const char *filename, int size);

DESCRIPTION
       Attempts  to  make a relative filename from an absolute path and an absolute filename, storing at most `size' bytes into the `dest' buffer.
       This function won't work if the paths are not canonical under the current platform (see canonicalize_filename()). Also,	`dest'	cannot	be
       used as input value for `path' or `filename'. Example:

	  char base[] = "/long/absolute/path/program.exe";
	  char user_input[] = "/nice/and/short.txt";
	  ...
	  make_relative_filename(buf, base, user_input, sizeof(buf));
	  /* Under Unix buf would contain:
	     ../../../nice/and/short.txt */

RETURN VALUE
       Returns	a  copy  of  the  `dest'  parameter if it succeeds or NULL if it fails (eg. under DOS, one path starts with "C:" and another with
       "A:").

SEE ALSO
       make_absolute_filename(3alleg4), is_relative_filename(3alleg4), canonicalize_filename(3alleg4)

Allegro 							   version 4.4.2				   make_relative_filename(3alleg4)