How to convert string to wstring in C++

Question

I have programmed some code but there is some problem. In this codes i am trying to convert string to wstring. But this string have \"█\" characters. This character have 219

Answer 1

The C-library solution for converting between the system's narrow and wide encoding use the mbsrtowcs and wcsrtombs functions from the <cwchar> header. I've spelt this out in this answer.

In C++11, you can use the wstring_convert template instantiated with a suitable codecvt facet. Unfortunately this requires some custom rigging, which is spelt out on the cppreference page.

I've adapted it here into a self-contained example which converts a wstring to a string, converting from the system's wide into the system's narrow encoding:

#include <iostream>
#include <string>
#include <locale>
#include <codecvt>

// utility wrapper to adapt locale-bound facets for wstring/wbuffer convert
template <typename Facet>
struct deletable_facet : Facet
{
    using Facet::Facet;
};

int main()
{
    std::wstring_convert<
        deletable_facet<std::codecvt<wchar_t, char, std::mbstate_t>>> conv;

    std::wstring ws(L"Hello world.");
    std::string ns = conv.to_bytes(ws);

    std::cout << ns << std::endl;
}