isdigit, iswdigit, _isdigit_l, _iswdigit_l
Determines whether an integer represents a decimal-digit character.
Syntax
int isdigit(
int c
);
int iswdigit(
wint_t c
);
int _isdigit_l(
int c,
_locale_t locale
);
int _iswdigit_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 a decimal-digit character. isdigit returns a nonzero value if c is a decimal digit (0 - 9). iswdigit returns a nonzero value if c is a wide character that corresponds to a decimal-digit character. 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 that's passed in instead of the current locale for their locale-dependent behavior. For more information, see Locale.
The behavior of isdigit and _isdigit_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 |
|---|---|---|---|
_istdigit |
isdigit |
_ismbcdigit |
iswdigit |
_istdigit_l |
_isdigit_l |
_ismbcdigit_l |
_iswdigit_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 |
|---|---|
isdigit |
<ctype.h> |
iswdigit |
<ctype.h> or <wchar.h> |
_isdigit_l |
<ctype.h> |
_iswdigit_l |
<ctype.h> or <wchar.h> |
For more compatibility information, see Compatibility.