isalnum, iswalnum, _isalnum_l, _iswalnum_l
The latest version of this topic can be found at 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 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 |
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.