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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.
- Integer to test.
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|
|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.
All versions of the C run-time libraries.