isalnum-iswalnum-isalnum-l-iswalnum-l.md

description	Learn more about: isalnum, iswalnum, _isalnum_l, _iswalnum_l
title	isalnum, iswalnum, _isalnum_l, _iswalnum_l
ms.date	4/2/2020
api_name	_iswalnum_l _isalnum_l iswalnum isalnum _o_isalnum _o_iswalnum
api_location	msvcrt.dll msvcr80.dll msvcr90.dll msvcr100.dll msvcr100_clr0400.dll msvcr110.dll msvcr110_clr0400.dll msvcr120.dll msvcr120_clr0400.dll ucrtbase.dll api-ms-win-crt-string-l1-1-0.dll ntoskrnl.exe
api_type	DLLExport
topic_type	apiref
f1_keywords	_istalnum_l _iswalnum_l iswalnum _isalnum_l isalnum _istalnum
helpviewer_keywords	_istalnum function _ismbcalnum_l function iswalnum function isalnum function istalnum function _isalnum_l function _istalnum_l function _iswalnum_l function
ms.assetid	0dc51306-ade8-4944-af27-e4176fc89093

isalnum, iswalnum, _isalnum_l, _iswalnum_l

Determines whether an integer represents an alphanumeric character.

Syntax

int isalnum( int c );
int iswalnum( wint_t c );
int _isalnum_l( int c,  _locale_t locale );
int _iswalnum_l( wint_t c, _locale_t locale );

Parameters

c
Integer to test.

locale
The locale to use.

Return value

Each of these routines returns nonzero if c is a particular representation of an alphanumeric character. isalnum returns a nonzero value if either isalpha or isdigit is nonzero for c, that is, if c is within the ranges A - Z, a - z, or 0 - 9. iswalnum returns a nonzero value if either iswalpha or iswdigit is nonzero for c. Each of these routines returns 0 if c doesn't satisfy the test condition.

The versions of these functions that have the _l suffix use the locale parameter that's passed in instead of the current locale. For more information, see Locale.

The behavior of isalnum and _isalnum_l is undefined if c isn't EOF or in the range 0 through 0xFF, inclusive. When a debug CRT library is used and c isn't one of these values, the functions raise an assertion.

Generic-text routine mappings

TCHAR.H routine	_UNICODE and _MBCS not defined	_MBCS defined	_UNICODE defined
_istalnum	isalnum	_ismbcalnum	iswalnum
_istalnum_l	_isalnum_l	_ismbcalnum_l	_iswalnum_l

Remarks

By default, this function's global state is scoped to the application. To change this behavior, see Global state in the CRT.

Requirements

Routine	Required header
isalnum	<ctype.h>
iswalnum	<ctype.h> or <wchar.h>
_isalnum_l	<ctype.h>
_iswalnum_l	<ctype.h> or <wchar.h>

For more compatibility information, see Compatibility.

See also

Character classification
Locale
is, isw routines