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
);
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 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 |
iswalnum |
|
_istalnum_l |
_isalnum_l |
_ismbcalnum_l |
_iswalnum_l |
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 additional compatibility information, see Compatibility in the Introduction.