Export (0) Print
Expand All

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

Show:
© 2014 Microsoft