Character Manipulation Function

int isdigit(int c);

int iswdigit(wint_t c);

int _ismbcdigit(unsigned int c);

int _istdigit(_TINT c);

Internationalization (I18n) Function Overview

The isdigit function returns a non-zero value if c is a digit.

iswdigit is the wide character version of isdigit, testing the wide character c.

Supported only on Windows platforms, _ismbcdigit is the multibyte equivalent, treating c as a multibyte character.

_istdigit is the Windows-only Generic version of the function; with the _MBCS or _UNICODE compiler flags determining its mapping to either _ismcbdigit or iswdigit.

I18n Issues

Use the appropriate version of the function as required for internationalization support, noting the following:

On ANSI platforms, there is no multibyte version of isdigit. Instead, convert the character c to a wide character and call iswdigit.

Prior to calling iswdigit on ANSI platforms, ensure that the locale is set correctly, since the result of the test condition depends on the locale's LC_CTYPE category setting. On Windows platforms, the iswdigit test is independent of locale.

The _ismbcdigit function depends on the multibyte code page in effect. By default, the multibyte code page is set to the system-default ANSI code page obtained from the operating system at program startup. Use _getmbcp and _setmbcp to query or change the current multibyte code page, respectively.

Recommended Replacements*

ANSI UTF-8	convert to wide and call iswdigit
ANSI UTF-16	iswdigit
Microsoft Windows MBCS	_ismbcdigit
Microsoft Windows Unicode	iswdigit
Microsoft Windows Generic	_istdigit

Character Manipulation Functions