NAME

isalpha, isupper, islower, isdigit, isxdigit, isalnum, isspace, ispunct, isprint, isgraph, iscntrl, isascii − classify characters

SYNOPSIS

#include <ctype.h>

int isalpha (c)
int c;

. . . 

DESCRIPTION

These macros classify character-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 (−1 − see stdio(3S)).

isalpha c is a letter. 

isupper c is an upper-case letter. 

islower c is a lower-case letter. 

isdigit c is a digit [0-9]. 

isxdigit c is a hexadecimal digit [0-9], [A-F] or [a-f]. 

isalnum c is an alphanumeric (letter or digit). 

isspace c is a space, tab, carriage return, new-line, vertical tab, or form-feed. 

ispunct c is a punctuation character (any printing character except space, digit, letter). 

isprint c is a printing character, code 040 (space) through 0176 (tilde). 

isgraph c is a printing character, like isprint except false for space. 

iscntrl c is a delete character (0177) or an ordinary control character (less than 040). 

isascii c is an ASCII character, code less than 0200. 

DIAGNOSTICS

If the argument to any of these macros is not in the domain of the function, the result is undefined. 

SEE ALSO

stdio(3S), ascii(5). 

Hewlett-Packard Company  —  Version B.1,  May 11, 2021