# std::wstring_convert

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< cpp‎ | locale

Defined in header `<locale>` |  |
template< class Codecvt, class Elem = wchar_t, class Wide_alloc = std::allocator<Elem>, class Byte_alloc = std::allocator<char> > class wstring_convert; |  | (since C++11) (deprecated in C++17)

Class template std::wstring_convert performs conversions between byte string std::string and wide string std::basic_string<Elem>, using an individual code conversion facet `Codecvt`. std::wstring_convert assumes ownership of the conversion facet, and cannot use a facet managed by a locale. The standard facets suitable for use with std::wstring_convert are std::codecvt_utf8 for UTF-8/UCS2 and UTF-8/UCS4 conversions and std::codecvt_utf8_utf16 for UTF-8/UTF-16 conversions.

### Member types

Member type | Definition
`byte_string` | `std::basic_string<char, char_traits<char>, Byte_alloc>`
`wide_string` | `std::basic_string<Elem, char_traits<Elem>, Wide_alloc>`
`state_type` | `Codecvt::state_type`
`int_type` | `wide_string::traits_type::int_type`

### Member functions

(constructor) | constructs a new wstring_convert (public member function)
operator= | the copy assignment operator is deleted (public member function)
(destructor) | destructs the wstring_convert and its conversion facet (public member function)
from_bytes | converts a byte string into a wide string (public member function)
to_bytes | converts a wide string into a byte string (public member function)
converted | returns the number of characters successfully converted (public member function)
state | returns the current conversion state (public member function)

### See also

Character conversions | locale-defined multibyte (UTF-8, GB18030) | UTF-8 | UTF-16
--- | --- | --- | ---
UTF-16 | `mbrtoc16` / `c16rtomb`(with C11's DR488) | `codecvt`<char16_t, char, mbstate_t> `codecvt_utf8_utf16`<char16_t> `codecvt_utf8_utf16`<char32_t> `codecvt_utf8_utf16`<wchar_t> | N/A
UCS2 | `c16rtomb`(without C11's DR488) | `codecvt_utf8`<char16_t> `codecvt_utf8`<wchar_t>(Windows) | `codecvt_utf16`<char16_t> `codecvt_utf16`<wchar_t>(Windows)
UTF-32 | `mbrtoc32` / `c32rtomb` | `codecvt`<char32_t, char, mbstate_t> `codecvt_utf8`<char32_t> `codecvt_utf8`<wchar_t>(non-Windows) | `codecvt_utf16`<char32_t> `codecvt_utf16`<wchar_t>(non-Windows)
system wide: UTF-32(non-Windows) UCS2(Windows) | `mbsrtowcs` / `wcsrtombs` `use_facet`<`codecvt` <wchar_t, char, mbstate_t>>(`locale`) | No | No

wbuffer_convert (C++11)(deprecated in C++17) | performs conversion between a byte stream buffer and a wide stream buffer (class template)
codecvt_utf8 (C++11)(deprecated in C++17) | converts between UTF-8 and UCS2/UCS4 (class template)
codecvt_utf8_utf16 (C++11)(deprecated in C++17) | converts between UTF-8 and UTF-16 (class template)

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