std::wbuffer_convert<Codecvt,Elem,Tr>::wbuffer_convert

wbuffer_convert() : wbuffer_convert(nullptr) { }

(1)

explicit wbuffer_convert( std::streambuf* bytebuf,
                          Codecvt* pcvt = new Codecvt,
                          state_type state = state_type() );

(2)

wbuffer_convert(const std::wbuffer_convert&) = delete;

(3)

(since C++14)

1) Default constructor.

2) Constructs the wbuffer_convert object with the specified underlying byte stream, specified codecvt facet, and specified initial conversion state (all parameters are optional)

3) The copy constructor is deleted, wbuffer_convert is not CopyConstructible

Parameters

bytebuf	-	pointer to std::streambuf to serve as the underlying narrow character stream
pcvt	-	pointer to a standalone (not managed by a locale) `std::codecvt` facet. The behavior is undefined if this pointer is null.
state	-	the initial value of the character conversion state

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

#include <iostream>
#include <sstream>
#include <locale>
#include <codecvt>
int main()
{
    // wrap a UTF-8 string stream in a UCS4 wbuffer_convert
    std::stringbuf utf8buf(u8"z\u00df\u6c34\U0001f34c");  // or u8"zß水????"
                       // or "\x7a\xc3\x9f\xe6\xb0\xb4\xf0\x9f\x8d\x8c";
    std::wbuffer_convert<std::codecvt_utf8<wchar_t>> conv_in(&utf8buf);
    std::wistream ucsbuf(&conv_in);
    std::cout << "Reading from a UTF-8 stringbuf via wbuffer_convert:\n";
    for(wchar_t c; ucsbuf.get(c); )
        std::cout << std::hex << std::showbase << c << '\n';
 
    // wrap a UTF-8 aware std::cout in a UCS4 wbuffer_convert to output UCS4
    std::wbuffer_convert<std::codecvt_utf8<wchar_t>> conv_out(std::cout.rdbuf());
    std::wostream out(&conv_out);
    std::cout << "Sending UCS4 data to std::cout via wbuffer_convert:\n";
    out << L"z\u00df\u6c34\U0001f34c\n";
}

Output:

Reading from a UTF-8 stringbuf via wbuffer_convert produces
0x7a
0xdf
0x6c34
0x1f34c
Sending UCS4 data to std::cout via wbuffer_convert:
zß水????

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