int isalpha( int c );
int iswalpha( wint_t c );
Each of these routines returns true if c is a particular representation of an alphabetic character.
| Routine | Required Header | Compatibility |
| isalpha | <ctype.h> | ANSI, Win 95, Win NT |
| iswalpha | <ctype.h> or <wchar.h> | ANSI, Win 95, Win NT |
For additional compatibility information, see Compatibility in the Introduction.
Libraries
| LIBC.LIB | Single thread static library, retail version |
| LIBCMT.LIB | Multithread static library, retail version |
| MSVCRT.LIB | Import library for MSVCRT.DLL, retail version |
Return Value
isalpha returns a non-zero value if c is within the ranges A – Z or a – z. iswalpha returns a non-zero value only for wide characters for which iswupper or iswlower is true, that is, for any wide character that is one of an implementation-defined set for which none of iswcntrl, iswdigit, iswpunct, or iswspace is true. 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.
Parameter
c
Integer to test
Generic-Text Routine Mappings
| TCHAR.H Routine | _UNICODE & _MBCS Not Defined | _MBCS Defined | _UNICODE Defined |
| _istalpha | isalpha | _ismbcalpha | iswalpha |
Character Classification Routines | Locale Routines | is, isw Function Overview