man empty_string () - Universal string NULL terminator. Allegro game programming library.
NAME
empty_string - Universal string NULL terminator. Allegro game programming library.
SYNOPSIS
#include <allegro.h>
extern char empty_string[];
DESCRIPTION
You can't just rely on "" to be a valid empty string in any encoding format. This global buffer contains a number of consecutive zeros, so it will be a valid empty string no matter whether the program is running in ASCII, Unicode, or UTF-8 mode.