Name
isalnum, isalpha, isascii, isblank, iscntrl, isdigit,
isgraph, islower, isprint, ispunct, isspace, isupper,
isxdigit — character classification routines
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; in the standard
"C" locale,
it is equivalent to (isupper(c) || islower(c)). 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.
isblank()-
checks for a blank character; that is, a space or a
tab.
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 ('\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 a b c d e f
A B C D E F.
RETURN VALUE
The values returned are non-zero if the character
c falls into the
tested class, and a zero value if not.
CONFORMING TO
C99, 4.3BSD. C89 specifies all of these functions except
isascii() and isblank(). isascii() is a BSD extension and is also an
SVr4 extension. isblank()
conforms to POSIX.1-2001 and C99 7.4.1.3.
NOTES
The details of what characters belong into which class
depend on the current locale. For example, isupper() will not recognize an A-umlaut
(Ä) as an uppercase letter in the default C locale.
SEE ALSO
iswalnum(3), iswalpha(3), iswblank(3), iswcntrl(3), iswdigit(3), iswgraph(3), iswlower(3), iswprint(3), iswpunct(3), iswspace(3), iswupper(3), iswxdigit(3), setlocale(3), tolower(3), toupper(3), ascii(7), locale(7)
(c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
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entire resulting derived work is distributed under the terms of a
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Since the Linux kernel and libraries are constantly changing, this
manual page may be incorrect or out-of-date. The author(s) assume no
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Formatted or processed versions of this manual, if unaccompanied by
the source, must acknowledge the copyright and authors of this work.
License.
Modified Sat Jul 24 19:10:00 1993 by Rik Faith (faith@cs.unc.edu)
Modified Sun Aug 21 17:51:50 1994 by Rik Faith (faith@cs.unc.edu)
Modified Sat Sep 2 21:52:01 1995 by Jim Van Zandt <jrv@vanzandt.mv.com>
Modified Mon May 27 22:55:26 1996 by Martin Schulze (joey@linux.de)
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