ctype.3c (2010 09)

c
ctype(3C) ctype(3C)
NAME
ctype: isalnum(), isalpha(), isascii(), isblank(), iscntrl(), isdigit(), isgraph(), islower(), isprint(), ispunct(),
isspace(), isupper(), isxdigit() - classify characters according to type
SYNOPSIS
#include <ctype.h>
int isalnum(int c);
int isalpha(int c);
int isascii(int c);
int isblank(int c);
int iscntrl(int c);
int isdigit(int c);
int isgraph(int c);
int islower(int c);
int isprint(int c);
int ispunct(int c);
int isspace(int c);
int isupper(int c);
int isxdigit(int c);
DESCRIPTION
These functions classify character-coded integer values according to the rules of the coded character set
identified by the last successful call to setlocale() (see setlocale (3C)). Each function is a predicate
returning nonzero for true, zero for false.
If
setlocale() has not been called successfully, characters are classified according to the rules of the
default ASCII 7-bit coded character set (see setlocale (3C)).
isascii() is defined on all integer values; the other functions are defined for the range
-1 (EOF)
through
255.
RETURN VALUE
The functions return nonzero under the following circumstances; zero otherwise:
isalnum(c) c is an alphanumeric (letters or digits).
isalpha(c) c is a letter.
isascii(c) c is any ASCII character code between 0 and 0177, inclusive.
isblank(c) c is a blank character; that is, a space or a tab.
iscntrl(c) c is a control character (in ASCII: character codes less than 040 and the delete
character (0177)).
isdigit(c) c is a decimal digit (in ASCII: characters [0-9]).
isgraph(c) c is a visible character (in ASCII: printing characters, excluding the space
character (040)).
islower(c) c is a lowercase letter.
isprint(c) c is a printing character.
ispunct(c) c is a punctuation character (in ASCII: any printing character except the space
character (040), digits, letters).
isspace(c) c is a character that creates whitespace in displayed text (in ASCII: space, tab,
carriage return, newline, vertical tab, and formfeed).
isupper(c) c is an uppercase letter.
isxdigit(c) c is a hexadecimal digit (in ASCII: characters [0-9], [A-F] or [a-f]).
If the argument to any of these functions is outside the domain of the function, the result is undefined.
EXTERNAL INFLUENCES
Environment Variables
The LC_CTYPE category determines the classification of character type.
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1