C_ALPHA
} else if (ctype(c, C_ALPHA)) {
} while (ctype(c, C_ALPHA|C_DIGIT));
ctypes[c] |= C_ALPHA;
ctypes[c] |= C_ALPHA;
ctypes['_'] |= C_ALPHA;
#define letter(c) ctype(c, C_ALPHA)
#define letnum(c) ctype(c, C_ALPHA|C_DIGIT)