isdigit, iswdigit
int isdigit( int c ); int iswdigit( wint_t c );
Each of these routines returns nonzero if c is a particular representation of a decimal-digit character.
Parameter
- c
- Integer to test.
Return Value
isdigit returns a non-zero value if c is a decimal digit (0 – 9). iswdigit returns a non-zero value if c is a wide character corresponding to a decimal-digit character. Each of these routines returns 0 if c does not satisfy the test condition.
The result of the test condition for the isdigit function depends on the LC_CTYPE category setting of the current locale; see setlocale for more information. For iswdigit, the result of the test condition is independent of locale.
When used with a debug CRT library, isdigit will display a CRT assert if passed a parameter that isn't EOF or in the range of 0 through 0xFF. When used with a debug CRT library, isdigit will use the parameter as an index into an array, with undefined results if the parameter isn't EOF or in the range of 0 through 0xFF.
Generic-Text Routine Mappings
| TCHAR.H routine | _UNICODE & _MBCS not defined | _MBCS defined | _UNICODE defined |
|---|---|---|---|
| _istdigit | isdigit | _ismbcdigit | iswdigit |
Requirements
| Routine | Required header | Compatibility |
|---|---|---|
| isdigit | <ctype.h> | ANSI, Win 98, Win Me, Win NT, Win 2000, Win XP |
| iswdigit | <ctype.h> or <wchar.h> | ANSI, Win 98, Win Me, Win NT, Win 2000, Win XP |
For additional compatibility information, see Compatibility in the Introduction.
Libraries
All versions of the C run-time libraries.
See Also
Character Classification Routines | Locale Routines | is, isw Function Overview | Run-Time Routines and .NET Framework Equivalents
