ISDIGIT
#define ISDIGIT 01 /* a digit */
#define ISDIGIT(c) isdigit((unsigned char)(c))
#define ISDIGIT(c) ((c) >= '0' && (c) <= '9')
#define ISDIGIT(x) ( (x) >= '0' && (x) <= '9' )
#define ISDIGIT(c) (isascii ((unsigned char)c) && isdigit ((unsigned char)c))