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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 
);

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. For more information, see 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

isalpha

<ctype.h>

iswalpha

<ctype.h> or <wchar.h>

_isalpha_l

<ctype.h>

_iswalpha_l

<ctype.h> or <wchar.h>

For additional compatibility information, see Compatibility in the Introduction.

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