CTYPE(3) CTYPE(3)
NAME
isalpha, isupper, islower, isdigit, isxdigit, isalnum,
isspace, ispunct, isprint, isgraph, iscntrl, isascii -
character classification
SYNOPSIS
#include <ctype.h> isalnum(c)
isalpha(c) isspace(c)
isupper(c) ispunct(c)
islower(c) isprint(c)
isdigit(c) isgraph(c)
isxdigit(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; stdio(3).
isalpha c is a letter, a-z or A-Z
isupper c is an upper case letter, A-Z
islower c is a lower case letter, a-z
isdigit c is a digit, 0-9
isxdigit c is a hexadecimal digit, 0-9 or a-f or A-F
isalnum c is an alphanumeric character, a-z or A-Z or 0-9
isspace c is a space, horizontal tab, vertical tab, car-
riage return, newline, or formfeed (040, 011, 012,
013, 014, 015)
ispunct c is a punctuation character (one of !"#$%&'()*+,-
./:;<=>?@[\]^_`{|}~)
isprint c is a printing character, 040 (space) through 0176
(tilde)
isgraph c is a visible printing character, 041
CTYPE(3) CTYPE(3)
(exclamation) through 0176 (tilde)
iscntrl c is a delete character, 0177, or ordinary control
character, 000 through 037
isascii c is an ASCII character, 000 through 0177
SEE ALSO
tolower(3), ascii(6)