isalpha, iswalpha, _isalpha_l, _iswalpha_l
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Determines whether an integer represents an alphabetic character.
Syntax
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
);
Parameters
c
Integer to test.
locale
The locale to use instead of the current locale.
Return Value
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 |
|---|---|---|---|
_istalpha |
isalpha |
_ismbcalpha |
iswalpha |
_istalpha_l |
_isalpha_l |
_ismbcalpha_l |
_iswalpha_l |
Requirements
| 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.