cwchar

cwchar is a C++ standard library header that provides facilities for handling wide characters, mirroring the C header wchar.h. It declares types, constants, and a set of functions for processing wchar_t strings and for converting between wide-character and multibyte representations. In typical C++ usage, these facilities are provided in the std namespace, while some implementations expose them in the global namespace as well.

Core types include wchar_t, used to represent individual wide characters; mbstate_t, which records the conversion state for multibyte-to-wide and wide-to-multibyte transitions; and the macro WEOF, used to indicate end-of-file in wide streams. cwchar forms part of the bridge between C and C++ wide-character support.

Function families include wide-string operations (such as wcslen, wcscpy, wcscat, and wcscmp) for manipulating wide-character sequences; and conversion routines (such as wcstombs, mbstowcs, wcsrtombs, and mbsrtowcs) for translating between wide strings and multibyte sequences. The header also provides wide I/O facilities such as fwprintf, fgetwc, fputwc, and their variants when used with wide streams.

Usage notes: include <cwchar> and refer to names in std:: (e.g., std::wcslen). The C and C++ standards ensure compatibility with the corresponding C library; it is common to use cwchar alongside <cwctype> for classification and transformation of wide characters.

See also: wchar.h, cwctype, and wide-character I/O.