ISALPHA (3)
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 "C"
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 c 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
and
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.
isascii() is a BSD extension
and is also an SVID extension.
isblank() 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.
SEE ALSO
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