iswspace

iswspace is a wide-character classification function in the C standard library. It tests whether a given wide character is considered whitespace in the current locale. The function is declared in the header <wctype.h> and takes a wint_t argument, returning a nonzero value if the character is classified as whitespace, and zero otherwise.

The set of characters that count as whitespace is locale-dependent. In the default C locale it typically includes ASCII whitespace such as space, horizontal tab, newline, vertical tab, form feed, and carriage return. In other locales, additional wide characters may be treated as whitespace, depending on the locale data loaded for LC_CTYPE.

Usage and portability: iswspace compares wide characters, so it is the wide-character counterpart to isspace. In C, you may call it with a wchar_t value promoted to wint_t, for example iswspace(L' '), iswspace(L'\n'), or iswspace(L'A'). In C++, the equivalent is std::iswspace in the header <cwctype> (often used within the std namespace). To affect locale-dependent classification, set the locale with setlocale(LC_CTYPE, "") or another locale string before using iswspace.

Notes: The argument wc should be a wide character value representable as a wint_t. Passing an invalid value yields unspecified or undefined behavior according to the C standard. iswspace is widely supported across modern C and C++ standard libraries.