isalnum, iswalnum, _isalnum_l, _iswalnum_l

Determines whether an integer represents an alphanumeric character.

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 does not 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 is not EOF or in the range 0 through 0xFF, inclusive. When a debug CRT library is used and c is not one of these values, the functions raise an assertion.

Generic-Text Routine Mappings

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

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 additional compatibility information, see Compatibility.

.NET Framework Equivalent

System::Char::IsLetterOrDigit

See Also

Reference

Character Classification

Locale

is, isw Routines