iswalpha, iswalpha_l - test for an alphabetic wide-character code
int iswalpha(wint_t wc);
[CX] int iswalpha_l(wint_t wc, locale_t locale);
For iswalpha(): [CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2008 defers to the ISO C standard.
The iswalpha() [CX] and iswalpha_l() functions shall test whether wc is a wide-character code representing a character of class alpha in the current locale, [CX] or in the locale represented by locale, respectively; see XBD Locale.
The wc argument is a wint_t, the value of which the application shall ensure is a wide-character code corresponding to a valid character in the locale used by the function, or equal to the value of the macro WEOF. If the argument has any other value, the behavior is undefined.
[CX] The behavior is undefined if the locale argument to iswalpha_l() is the special locale object LC_GLOBAL_LOCALE or is not a valid locale object handle.
The iswalpha() [CX] and iswalpha_l() functions shall return non-zero if wc is an alphabetic wide-character code; otherwise, they shall return 0.
No errors are defined.
To ensure applications portability, especially across natural languages, only these functions and the functions in the reference pages listed in the SEE ALSO section should be used for character classification.
iswalnum, iswcntrl, iswctype, iswdigit, iswgraph, iswlower, iswprint, iswpunct, iswspace, iswupper, iswxdigit, setlocale, uselocale
XBD Locale, <locale.h>, <wctype.h>
First released in Issue 4.
The following change has been made in this version for alignment with ISO/IEC 9899:1990/Amendment 1:1995 (E):
The normative text is updated to avoid use of the term "must" for application requirements.
The iswalpha_l() function is added from The Open Group Technical Standard, 2006, Extended API Set Part 4.
POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0312 , XSH/TC1-2008/0313 , and XSH/TC1-2008/0314  are applied.
POSIX.1-2008, Technical Corrigendum 2, XSH/TC2-2008/0181  is applied.
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