isalnum, iswalnum, _isalnum_l, _iswalnum_l


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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  


Integer to test.

The locale to use.

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
RoutineRequired header
iswalnum<ctype.h> or <wchar.h>
_iswalnum_l<ctype.h> or <wchar.h>

For additional compatibility information, see Compatibility.


Character Classification
is, isw Routines