ISALNUM(3P) POSIX Programmer's Manual ISALNUM(3P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding
Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
NAMEisalnum - test for an alphanumeric character
SYNOPSIS
#include <ctype.h>
int isalnum(int c);
DESCRIPTION
The isalnum() function shall test whether c is a character of class
alpha or digit in the program's current locale; see the Base Defini‐
tions volume of IEEE Std 1003.1-2001, Chapter 7, Locale.
The c argument is an int, the value of which the application shall
ensure is representable as an unsigned char or equal to the value of
the macro EOF. If the argument has any other value, the behavior is
undefined.
RETURN VALUE
The isalnum() function shall return non-zero if c is an alphanumeric
character; otherwise, it shall return 0.
ERRORS
No errors are defined.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
To ensure applications portability, especially across natural lan‐
guages, only this function and those listed in the SEE ALSO section
should be used for character classification.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSOisalpha(), iscntrl(), isdigit(), isgraph(), islower(), isprint(),
ispunct(), isspace(), isupper(), isxdigit(), setlocale(), the Base Def‐
initions volume of IEEE Std 1003.1-2001, Chapter 7, Locale, <ctype.h>,
<stdio.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 ISALNUM(3P)
