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isalpha, iswalpha, _isalpha_l, _iswalpha_l


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The latest version of this topic can be found at isalpha, iswalpha, _isalpha_l, _iswalpha_l.

Determines whether an integer represents an alphabetic character.

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   


Integer to test.

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.

The versions of these functions that have the _l suffix use the locale parameter that's passed in instead of the current locale. For more information, see Locale.

The behavior of isalpha and _isalpha_l is undefined if c is not EOF or in the range 0 through 0xFF, inclusive. When a debug CRT library is used and c is not one of these values, the functions raise an assertion.

Generic-Text Routine Mappings

TCHAR.H routine_UNICODE & _MBCS not defined_MBCS defined_UNICODE defined
RoutineRequired header
iswalpha<ctype.h> or <wchar.h>
_iswalpha_l<ctype.h> or <wchar.h>

For additional compatibility information, see Compatibility.


Character Classification
is, isw Routines