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isalnum, iswalnum, _isalnum_l, _iswalnum_l

Determines if a particular character is 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
);

c

Integer to test.

locale

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.

When used with a debug CRT library, isalnum will display a CRT assert if passed a parameter that is not EOF or in the range of 0 through 0xFF. isalnum will use the parameter as an index into an array, with undefined results if the parameter is not EOF or in the range of 0 through 0xFF.

The versions of these functions with the _l suffix are identical except that they use the locale parameter passed in instead of the current locale. For more information, see Locale.

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

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 in the Introduction.

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