islower
Hurricane Electric Internet Services
NAME
isalnum, isalpha, 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 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 equiva-
lent to (isalpha(c) || isdigit(c)).
isalpha()
checks for an alphabetic character; it is equiva-
lent to (isupper(c) || islower(c)).
iscntrl()
checks for a control character.
isdigit()
checks for a digit.
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
('\f'), newline ('\n'), carriage return ('\r'),
horizontal tab ('\t'), and vertical tab ('\v').
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 0 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.
CONFORMS TO
ANSI - C, BSD 4.3
BUGS
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.
SEE ALSO
toupper(3), setlocale(3), ascii(7), locale(7)
Hurricane Electric Internet Services
Copyright (C) 1998
Hurricane Electric.
All Rights Reserved.