From X-Plane SDK
XPLM_API char * XPLMExtractFileAndPath( char * inFullPath);Given a full path to a file, this routine separates the path from the file. If the path is a partial directory (e.g. ends in : or \) the trailing directory separator is removed. This routine works in-place; a pointer to the file part of the buffer is returned; the original buffer still starts with the path.