ctype(3C)
NAME
isdigit, isxdigit, islower, isupper, isalpha, isalnum, isspace, iscntrl, ispunct, isprint, isgraph, isascii − character handling
SYNOPSIS
#include <ctype.h>
int isdigit (c)
int c;
. . .
DESCRIPTION
The character classification macros listed below return nonzero for true, zero for false. isascii is defined on all integer values; the rest are defined on valid members of the character set and on the single value EOF (guaranteed not to be a character set member, see stdio(3S)).
isdigit tests for the digits 0 through 9.
isxdigit tests for hexadecimal digits, any character for which isdigit is true or which is one of the letters a through f or A through F.
islower tests for any lowercase letter as defined by the character set.
isupper tests for any uppercase letter as defined by the character set.
isalpha tests for any character for which islower or isupper is true and possibly any others as defined by the character set.
isalnum tests for any character for which isalpha or isdigit is true.
isspace tests for a space, horizontal-tab, carriage return, newline, vertical-tab, or form-feed.
iscntrl tests for “control characters” as defined by the character set.
ispunct tests for any character other than the ones for which isalnum, iscntrl, or isspace is true or space.
isprint tests for a space or any character for which isalnum or ispunct is true or other “printing character” as defined by the character set.
isgraph tests for any character for which isprint is true, except for space.
isascii tests for an ASCII character (a non-negative number less than 0200.)
All the character classification macros except isascii do a table lookup.
The tables used by these macros may be loaded by setlocale(3C) or by setchrclass(3C) to correspond to a specific locale.
SEE ALSO
conv(3C), stdio(3S), setchrclass(3C), setlocale(3C), ascii(5), environ(5).
chrtbl(1M) in the CX/UX Administrator’s Reference Manual.
DIAGNOSTICS
If the argument to any of the character handling macros is not in the domain of the function, the result is undefined.
CX/UX Programmer’s Reference Manual