ISALPHA

NAME

isalnum, isalpha, isascii, isblank, iscntrl, isdigit, isgraph, islower, isprint, ispunct, isspace, isupper, isxdigit - character classification routines

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 check whether c, which must have the value of an unsigned char or EOF, falls into a certain character class according to the current locale.

isalnum(): checks for an alphanumeric character; it is equivalent to (isalpha(c) || isdigit(c))fR.
isalpha(): checks for an alphabetic character; in the standard fB"C"fP locale, it is equivalent to (isupper(c) || islower(c))fR. In some locales, there may be additional characters for which isalpha() is true--letters which are neither upper case nor lower case.
isascii(): checks whether fIcfP is a 7-bit unsigned char value that fits into the ASCII character set. This function is a BSD extension and is also an SVID extension.
isblank(): checks for a blank character; that is, a space or a tab. This function is a GNU extension.
iscntrl(): checks for a control character.
isdigit(): checks for a digit (0 through 9).
isgraph(): checks for any printable character except space.
islower(): checks for a lower-case character.
isprint(): checks for any printable character including space.
ispunct(): checks for any printable character which is not a space or an alphanumeric character.
isspace(): checks for white-space characters. In the C and POSIX locales, these are: space, form-feed ('ef'), newline ('en'), carriage return ('er'), horizontal tab ('et'), and vertical tab ('ev').
isupper(): checks for an uppercase letter.
isxdigit(): checks for a hexadecimal digits, i.e. one of 0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F.

RETURN VALUE

The values returned are nonzero if the character c falls into the tested class, and a zero value if not.

CONFORMING TO

ANSI - C, BSD 4.3. fBisascii()fP is a BSD extension and is also an SVID extension. fBisblank()fP is a GNU extension.

NOTE

The details of what characters belong into which class depend on the current locale. For example, isupper() will not recognize an A - umlaut as an uppercase letter in the default C locale.