# std::wstring_convert<Codecvt,Elem,Wide_alloc,Byte_alloc>::wstring_convert

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< cpp‎ | locale‎ | wstring convert

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

### 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

### 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

### Example

Run this code

    #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"));
    }

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