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

 

C++

Language

Standard Library Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

 

Localizations library

Locales and facets
locale
use_facet	has_facet
Character classification
isspace isblank (C++11) iscntrl isupper islower isalpha	isdigit ispunct isxdigit isalnum isprint isgraph
Conversions
toupper tolower	wstring_convert (C++11) wbuffer_convert (C++11)
Facet category base classes
ctype_base codecvt_base messages_base	time_base money_base
Facet categories
ctype ctype<char> codecvt collate messages time_get time_put	num_get num_put numpunct money_get money_put moneypunct
Locale-specific facets
ctype_byname codecvt_byname messages_byname collate_byname	time_get_byname time_put_byname numpunct_byname moneypunct_byname
Code conversion facets
codecvt_utf8 (C++11) codecvt_utf16 (C++11)	codecvt_utf8_utf16 (C++11) codecvt_mode (C++11)
C locale
setlocale localeconv lconv	LC_ALLLC_COLLATELC_CTYPELC_MONETARYLC_NUMERICLC_TIME

 

std::wstring_convert

Member functions

wstring_convert::wstring_convert

wstring_convert::~wstring_convert

wstring_convert::from_bytes

wstring_convert::to_bytes

wstring_convert::converted

wstring_convert::state

 

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"));
}