1 .\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
3 .\" Permission is granted to make and distribute verbatim copies of this
4 .\" manual provided the copyright notice and this permission notice are
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7 .\" Permission is granted to copy and distribute modified versions of this
8 .\" manual under the conditions for verbatim copying, provided that the
9 .\" entire resulting derived work is distributed under the terms of a
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12 .\" Since the Linux kernel and libraries are constantly changing, this
13 .\" manual page may be incorrect or out-of-date. The author(s) assume no
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17 .\" which is licensed free of charge, as they might when working
20 .\" Formatted or processed versions of this manual, if unaccompanied by
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24 .\" Modified Sat Jul 24 19:10:00 1993 by Rik Faith (faith@cs.unc.edu)
25 .\" Modified Sun Aug 21 17:51:50 1994 by Rik Faith (faith@cs.unc.edu)
26 .\" Modified Sat Sep 2 21:52:01 1995 by Jim Van Zandt <jrv@vanzandt.mv.com>
27 .\" Modified Mon May 27 22:55:26 1996 by Martin Schulze (joey@linux.de)
29 .TH ISALPHA 3 2009-03-15 "GNU" "Linux Programmer's Manual"
31 isalnum, isalpha, isascii, isblank, iscntrl, isdigit, isgraph, islower,
32 isprint, ispunct, isspace, isupper, isxdigit \- character
33 classification routines
38 .BI "int isalnum(int " "c" );
40 .BI "int isalpha(int " "c" );
42 .BI "int isascii(int " "c" );
44 .BI "int isblank(int " "c" );
46 .BI "int iscntrl(int " "c" );
48 .BI "int isdigit(int " "c" );
50 .BI "int isgraph(int " "c" );
52 .BI "int islower(int " "c" );
54 .BI "int isprint(int " "c" );
56 .BI "int ispunct(int " "c" );
58 .BI "int isspace(int " "c" );
60 .BI "int isupper(int " "c" );
62 .BI "int isxdigit(int " "c" );
66 Feature Test Macro Requirements for glibc (see
67 .BR feature_test_macros (7)):
72 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE
75 _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE; or
79 These functions check whether
81 which must have the value of an
85 falls into a certain character class according to the current locale.
88 checks for an alphanumeric character; it is equivalent to
89 .BI "(isalpha(" c ") || isdigit(" c "))" \fR.
92 checks for an alphabetic character; in the standard \fB"C"\fP
93 locale, it is equivalent to
94 .BI "(isupper(" c ") || islower(" c "))" \fR.
95 In some locales, there may be additional characters for which
97 is true\(emletters which are neither upper case nor lower
101 checks whether \fIc\fP is a 7-bit
104 the ASCII character set.
107 checks for a blank character; that is, a space or a tab.
110 checks for a control character.
113 checks for a digit (0 through 9).
116 checks for any printable character except space.
119 checks for a lower-case character.
122 checks for any printable character including space.
125 checks for any printable character which is not a space or an
126 alphanumeric character.
129 checks for white-space characters.
134 locales, these are: space, form-feed
146 checks for an uppercase letter.
149 checks for a hexadecimal digits, that is, one of
151 .BR "0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F" .
153 The values returned are nonzero if the character
155 falls into the tested class, and a zero value
159 C89 specifies all of these functions except
165 and is also an SVr4 extension.
167 conforms to POSIX.1-2001 and C99 7.4.1.3.
171 noting that it cannot be used portably in a localized application.
173 The details of what characters belong into which class depend on the current
177 will not recognize an A-umlaut (\(:A) as an uppercase letter in the default