isdigit, iswdigit, _isdigit_l, _iswdigit_l
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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 does not 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 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 |
|---|---|---|---|
_istdigit |
isdigit |
_ismbcdigit | iswdigit |
_istdigit_l |
_isdigit_l |
_ismbcdigit_l | _iswdigit_l |
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 additional compatibility information, see Compatibility.