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 );
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.
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.
