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

Converts a wide sequence to a byte string using the facet pointed to by cvtptr .

Before the conversion begins, if * this was not constructed with constructor overload (3) , cvtstate will be set to its default value (the initial conversion state).

The number of input elements successfully converted will be stored in cvtcount .

Return value

If the conversion succeeds, returns the conversion result. Otherwise, if * this is constructed with constructor overload (4) , returns byte_err_string .

Exceptions

If the conversion fails and * this was not constructed with constructor overload (4) , throws std::range_error .

Example

#include <codecvt>
#include <iomanip>
#include <iostream>
#include <locale>
#include <string>
 
// utility function for output
void hex_print(const std::string& s)
{
    std::cout << std::hex << std::setfill('0');
    for (unsigned char c : s)
        std::cout << std::setw(2) << static_cast<int>(c) << ' ';
    std::cout << std::dec << '\n';
}
 
int main()
{
    // wide character data
    std::wstring wstr = L"z\u00df\u6c34\U0001f34c"; // or L"zß水🍌"
 
    // wide to UTF-8
    std::wstring_convert<std::codecvt_utf8<wchar_t>> conv1;
    std::string u8str = conv1.to_bytes(wstr);
    std::cout << "UTF-8 conversion produced " << u8str.size() << " bytes:\n";
    hex_print(u8str);
 
    // wide to UTF-16le
    std::wstring_convert<std::codecvt_utf16<wchar_t, 0x10ffff, std::little_endian>> conv2;
    std::string u16str = conv2.to_bytes(wstr);
    std::cout << "UTF-16le conversion produced " << u16str.size() << " bytes:\n";
    hex_print(u16str);
}

UTF-8 conversion produced 10 bytes:
7a c3 9f e6 b0 b4 f0 9f 8d 8c 
UTF-16le conversion produced 10 bytes:
7a 00 df 00 34 6c 3c d8 4c df

See also