Character Manipulation Function

int islower(int c);

int iswlower(wint_t c);

int _ismbclower(unsigned int c);

int _istlower(_TINT c);

Internationalization (I18n) Function Overview

The islower function tests for a lowercase character, using the LC_CTYPE category setting of the current locale.

iswlower is the wide character equivalent of islower, testing the wide character c.

On Windows platforms only, use _ismbclower for the multibyte character equivalent. It returns nonzero if c is a lowercase character within the current multibyte character set.

_istlower is the Windows-only Generic version of the function; with the _MBCS or _UNICODE compiler flags determining its mapping to either _ismbclower or iswlower.

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 islower. Instead, convert the character c to a wide character and call iswlower.

Prior to calling iswlower 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 iswlower test is independent of locale.

The _ismbclower 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 and call iswlower
ANSI UTF-16	iswlower
Microsoft Windows MBCS	_ismbclower
Microsoft Windows Unicode	iswlower
Microsoft Windows Generic	_istlower

Character Manipulation Functions