isdigit, iswdigit, _isdigit_l, _iswdigit_l

Determines if a particular character is a decimal-digit character.

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 corresponding to a decimal-digit character. Each of these routines returns 0 if c does not satisfy the test condition.

When used with a debug CRT library, isdigit will display a CRT assert if passed a parameter that is not 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 is not EOF or in the range of 0 through 0xFF.

The versions of these functions with the _l suffix are identical except that they use the locale passed in instead of the current locale for their locale-dependent behavior. For more information, see Locale.

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 in the Introduction.

.NET Framework Equivalent

System::Char::IsDigit

See Also

Concepts

Character Classification

Locale

is, isw Routines