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std::wstring_convert::wstring_convert

From cppreference.com
wstring_convert() : wstring_convert( new Codecvt ) { }
(1)
explicit wstring_convert( Codecvt* pcvt );
(2)
wstring_convert( Codecvt* pcvt, state_type state);
(3)
explicit wstring_convert( const byte_string& byte_err,
                          const wide_string& wide_err = wide_string() );
(4)
wstring_convert(const std::wstring_convert&) = delete;
(5) (since C++14)
1) Default constructor.
2) Constructs the wstring_convert object with a specified conversion facet, using default-constructed values for the shift state and the error strings
3) Constructs the wstring_convert object with a specified conversion facet and specified shift state, using default-constructed values for the error strings
4) Constructs the wstring_convert object with specified error strings, using new Codecvt as the conversion facet and the default-constructed state_type as shift state.
5) The copy constructor is deleted, wstring_convert is not CopyConstructible

[edit] Parameters

pcvt - pointer to the conversion facet of type Codecvt (behavior is undefined if this pointer is null)
state - initial value of the conversion shift state
byte_err - narrow string to display on errors
wide_err - wide string to display on errors

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
P0935R0 C++11 default constructor was explicit made implicit

[edit] Example

#include <locale>
#include <utility>
#include <codecvt>
 
// utility wrapper to adapt locale-bound facets for wstring/wbuffer convert
template<class Facet>
struct deletable_facet : Facet
{
    using Facet::Facet; // inherit constructors
    ~deletable_facet() {}
};
 
int main()
{
    // UTF-16le / UCS4 conversion
    std::wstring_convert<
         std::codecvt_utf16<char32_t, 0x10ffff, std::little_endian>
    > u16to32;
 
    // UTF-8 / wide string conversion with custom messages
    std::wstring_convert<std::codecvt_utf8<wchar_t>> u8towide("Error!", L"Error!");
 
    // GB18030 / wide string conversion facet
    typedef deletable_facet<std::codecvt_byname<wchar_t, char, std::mbstate_t>> F;
    std::wstring_convert<F> gbtowide(new F("zh_CN.gb18030"));
}