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isalnum, iswalnum

int isalnum( 
   int c 
);
int iswalnum( 
   wint_t c 
);

Each of these routines returns nonzero if c is a particular representation of an alphanumeric character.

Parameter

c
Integer to test.

Return Value

isalnum returns a non-zero 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 non-zero 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 result of the test condition for the isalnum function depends on the LC_CTYPE category setting of the current locale; see setlocale for more information. For iswalnum, the result of the test condition is independent of locale.

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

Generic-Text Routine Mappings

TCHAR.H routine _UNICODE & _MBCS not defined _MBCS defined _UNICODE defined
_istalnum isalnum _ismbcalnum iswalnum

Requirements

Routine Required header Compatibility
isalnum <ctype.h> ANSI, Win 98, Win Me, Win NT, Win 2000, Win XP
iswalnum <ctype.h> or <wchar.h> ANSI, Win 98, Win Me, Win NT, Win 2000, Win XP

For additional compatibility information, see Compatibility in the Introduction.

Libraries

All versions of the C run-time libraries.

See Also

Character Classification Routines | Locale Routines | is, isw Function Overview | Run-Time Routines and .NET Framework Equivalents

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