ISALPHA
Section: Linux Programmer's Manual (3)
Updated: April 4, 1993
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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 equivalent to
(isalpha(c) || isdigit(c)).
- isalpha()
-
checks for an alphabetic character; it is equivalent 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)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- CONFORMS TO
-
- BUGS
-
- SEE ALSO
-
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