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isalpha, iswalpha

int isalpha( 
   int c 
);
int iswalpha( 
   wint_t c 
);

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

Parameter

c
Integer to test.

Return Value

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.

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

When used with a debug CRT library, isalpha 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, isalpha 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
_istalpha isalpha _ismbcalpha iswalpha

Requirements

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