#include <iostream>
#include <string>
#include <windows.h>
#include <clocale>
#include <fstream>
#include <cwchar>
#include <cstdio>
using namespace std;

string toUTF8(const wstring& wstr) {
    int size_needed = WideCharToMultiByte(CP_UTF8, 0, wstr.c_str(), wstr.size(), NULL, 0, NULL, NULL);
    string str;
    str.resize(size_needed);
    WideCharToMultiByte(CP_UTF8, 0, wstr.c_str(), wstr.size(), &str[0], str.size(), NULL, NULL);
    return str;
}


wstring toUTF16(const string& str) {
    int size_needed = MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, str.c_str(), str.size(), NULL, 0);
    wstring wstr;
    wstr.resize(size_needed);
    MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, str.c_str(), str.size(), &wstr[0], wstr.size()); 
    return wstr;
}

class WFile {
    public:
        FILE* ptr;
        WFile(const wstring& filename, const wstring& mode) {
            ptr = _wfopen(filename.c_str(), mode.c_str());
        }
        ~WFile() {
            if (ptr) {
                fclose(ptr);
            }
        }
};

int main() {
    setlocale(LC_CTYPE, ".OCP");
    wstring wstr(L"\u221A");
    wcout << wstr << endl;
    cout << toUTF8(wstr) << endl;
    WFile wtest(L"utf-16.txt", L"wb, ccs=UTF-16LE");
    if (!wtest.ptr) {
        return EXIT_FAILURE;
    }
    fwprintf(wtest.ptr, L"\uFEFF");
    fwprintf(wtest.ptr, L"%s", toUTF16(toUTF8(wstr)).c_str());
    WFile test(L"utf-8.txt", L"wb, ccs=UTF-8");
    if (!test.ptr) {
        return EXIT_FAILURE;
    }
    fprintf(test.ptr, "%s", toUTF8(wstr).c_str());
}