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isalpha, iswalpha, _isalpha_l, _iswalpha_l 

Check an integer to see it is represents an alphabetic character in a character set.


int isalpha( 
   int c 
);
int iswalpha( 
   wint_t c 
);
int _isalpha_l( 
   int c,
   _locale_t locale 
);
int _iswalpha_l( 
   wint_t c,
   _locale_t locale 
);

Parameters

c

Integer to test.

locale

The locale to use instead of the current locale.

Each of these routines returns nonzero if c is a particular representation of an alphabetic character. isalpha returns a nonzero value if c is within the ranges A – Z or a – z. iswalpha returns a nonzero value only for wide characters for which iswupper or iswlower is nonzero, that is, for any wide character that is one of an implementation-defined set 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.

When used with a debug CRT library, isalpha 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 release CRT library, isalpha 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 parameter passed in instead of the current locale.

Generic-Text Routine Mappings
TCHAR.H routine _UNICODE & _MBCS not defined _MBCS defined _UNICODE defined

_istalpha

isalpha

_ismbcalpha

iswalpha

_istalpha_l

_isalpha_l

_ismbcalpha_l

_iswalpha_l

Routine Required header Compatibility

isalpha

<ctype.h>

ANSI, Windows 95, Windows 98, Windows 98 Second Edition, Windows Millennium Edition, Windows NT 4.0, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003

iswalpha

<ctype.h> or <wchar.h>

ANSI, Windows 95, Windows 98, Windows 98 Second Edition, Windows Millennium Edition, Windows NT 4.0, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003

_isalpha_l

<ctype.h>

Windows 95, Windows 98, Windows 98 Second Edition, Windows Millennium Edition, Windows NT 4.0, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003

_iswalpha_l

<ctype.h> or <wchar.h>

Windows 95, Windows 98, Windows 98 Second Edition, Windows Millennium Edition, Windows NT 4.0, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003

For additional compatibility information, see Compatibility in the Introduction.

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