isalnum, iswalnum, _isalnum_l, _iswalnum_l
Determines whether an integer represents an alphanumeric character.
Syntax
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 doesn't 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 isn't EOF or in the range 0 through 0xFF, inclusive. When a debug CRT library is used and c isn't one of these values, the functions raise an assertion.
Generic-text routine mappings
| TCHAR.H routine | _UNICODE and _MBCS not defined |
_MBCS defined |
_UNICODE defined |
|---|---|---|---|
_istalnum |
isalnum |
_ismbcalnum |
iswalnum |
_istalnum_l |
_isalnum_l |
_ismbcalnum_l |
_iswalnum_l |
Remarks
By default, this function's global state is scoped to the application. To change this behavior, see Global state in the CRT.
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 more compatibility information, see Compatibility.