#include <allegro5/allegro.h> bool al_set_path_extension(ALLEGRO_PATH *path, char const *extension)
Replaces the extension of the path with the given one, i.e. replaces everything from the final dot (`.') character onwards, including the dot. If the filename of the path has no extension, the given one is appended. Usually the new extension you supply should include a leading dot.
Returns false if the path contains no filename part, i.e. the filename part is the empty string.