Was this page helpful?
Your feedback about this content is important. Let us know what you think.
Additional feedback?
1500 characters remaining
Export (0) Print
Expand All
div
eof
Expand Minimize

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
);

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.

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

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.

Show:
© 2015 Microsoft