Character Manipulation Function

int isalpha(int c);

int iswalpha(wint_t c);

int _ismbcalpha(unsigned int c);

int _istalpha(_TINT c);

Internationalization (I18n) Function Overview

The isalpa function returns a non-zero value if c is within the A-Z or a-z ranges.

iswalpha is the wide character version of isalpha, testing the wide character c.

Supported only on Windows platforms, _ismbcalpha is the multibyte equivalent, treating c as a multibyte character and calling _ismbbalpha.

_istalpha is the Windows-only Generic version of the function; with the _MBCS or _UNICODE compiler flags determining its mapping to either _ismbcalpha or iswalpha.

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 isalpha. Instead, convert the character c to a wide character and call iswalpha.

Prior to calling iswalpha 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 iswalpha test is independent of locale.

The _ismbcalpha 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 iswalpha
ANSI UTF-16	iswalpha
Microsoft Windows MBCS	_ismbcalpha
Microsoft Windows Unicode	iswalpha
Microsoft Windows Generic	_istalpha

Character Manipulation Functions