CTYPE(3) CTYPE(3) NAME isalpha, isupper, islower, isdigit, isalnum, isspace, ispunct, isprint, iscntrl, isascii - character classification SYNOPSIS #include <ctype.h> isalnum(c) isalpha(c) isspace(c) isupper(c) ispunct(c) islower(c) isprint(c) isdigit(c) iscntrl(c) isascii(c) DESCRIPTION These macros classify ASCII-coded integer values by table lookup. Each is a predicate returning nonzero for true, zero for false. Isascii is defined on all integer values; the rest are defined only where isascii is true and on the single non-ASCII value EOF (see stdio(3)). isalpha c is a letter isupper c is an upper case letter islower c is a lower case letter isdigit c is a digit isalnum c is an alphanumeric character isspace c is a space, tab, carriage return, newline, or formfeed ispunct c is a punctuation character (neither control nor alphanumeric) isprint c is a printing character, code 040 octal (space) through 0176 (tilde) iscntrl c is a delete character (0177) or ordinary control character (less than 040). isascii c is an ASCII character, i.e. 0≦c<0200. SEE ALSO CTYPE(3) CTYPE(3) tolower(3), ascii(7)