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islower, iswlower

int islower(
   int c 
);
int iswlower(
   wint_t c 
);

Each of these routines returns nonzero if c is a particular representation of a lowercase character.

Parameter

c
Integer to test.

Return Value

islower returns a non-zero value if c is a lowercase character (a – z). iswlower returns a non-zero value if c is a wide character that corresponds to a lowercase letter, or if c is one of an implementation-defined set of wide characters for which none of iswcntrl, iswdigit, iswpunct, or iswspace is nonzero. Each of these routines returns 0 if c does not satisfy the test condition.

The result of the test condition for the islower function depends on the LC_CTYPE category setting of the current locale; see setlocale for more information. For iswlower, the result of the test condition is independent of locale.

When used with a debug CRT library, islower 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, islower 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
_istlower islower _ismbclower iswlower

Requirements

Routine Required header Compatibility
islower <ctype.h> ANSI, Win 98, Win Me, Win NT, Win 2000, Win XP
iswlower <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

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