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 );
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.
TCHAR.H routine | _UNICODE & _MBCS not defined | _MBCS defined | _UNICODE defined |
|---|---|---|---|
_istalnum | isalnum | 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.
