How can I efficiently convert a `wstring` to a `string` in C ?

Converting wstring to string in C

Issue

How can I convert a wstring to a string in C ? Consider the following example:

#include <string>
#include <iostream>

int main() {
    std::wstring ws = L"Hello";
    std::string s(ws.begin(), ws.end());

    std::cout << "std::string =     " << s << std::endl;
    std::wcout << "std::wstring =    " << ws << std::endl;
    std::cout << "std::string =     " << s << std::endl;
}

With the commented-out line, the output is:

std::string =     Hello
std::wstring =    Hello
std::string =     Hello

However, without it, the output is only:

std::wstring =    Hello

Answer

Using std::wstring_convert (C 11)

As pointed out by Cubbi, std::wstring_convert provides an easy solution:

#include <locale>
#include <codecvt>

std::wstring string_to_convert;

using convert_type = std::codecvt_utf8<wchar_t>;
std::wstring_convert<convert_type, wchar_t> converter;

// Convert wstring to string
std::string converted_str = converter.to_bytes(string_to_convert);

You can also use helper functions to simplify the conversion:

// Convert string to wstring
std::wstring s2ws(const std::string& str) {
    using convert_typeX = std::codecvt_utf8<wchar_t>;
    std::wstring_convert<convert_typeX, wchar_t> converterX;
    return converterX.from_bytes(str);
}

// Convert wstring to string
std::string ws2s(const std::wstring& wstr) {
    using convert_typeX = std::codecvt_utf8<wchar_t>;
    std::wstring_convert<convert_typeX, wchar_t> converterX;
    return converterX.to_bytes(wstr);
}

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