C++ Read UTF-8 (Lithuanian letters) symbols from txt file and show them in console application [duplicate] - c++

Question

This question already has answers here:
Read Unicode UTF-8 file into wstring
(7 answers)
Closed 1 year ago.
I need you help.
I'm using Windows 10 and Visual Studio Community compiler.
I managed to get Lithuanian letter to show on C++ console application using wstring and wcout.
#include <iostream>
#include <io.h>
#include <fcntl.h>
using namespace std;
int main()
{
_setmode(_fileno(stdout), _O_U16TEXT);
wstring a = L"ąėėąčėį";
wcout << a;
return 0;
}
Result is exactly what I wanted it to be
Now I want my program to read Lithuanian letters from Info.txt file.
This is how far I managed to get.
#include <iostream>
#include <fstream>
#include <io.h>
#include <fcntl.h>
#include <string>
using namespace std;
int main()
{
_setmode(_fileno(stdout), _O_U16TEXT);
wstring text;
wifstream fin("Info.txt");
getline(fin, text);
wcout << text;
return 0;
}
Returned string in console application shows different simbols.
But the returned string in console application shows different simbols.
In my belief a possible solution
I need to add L before the text like in previous example with wcout.
wstring a = L"ąėėąčėį";
But I'm still just learning C++ and I don't know how to do so in example with Info.txt
I need your help!

Answer 1

UTF8 needs std::ifstream, not wifstream. The latter is used in Windows as UTF16 file storage (not recommended in any system)
You can use SetConsoleOutputCP(CP_UTF8) to enable UTF8 printing, but that can run in to problems, specially in C++ 20
Instead, call _setmode and convert UTF8 to UTF16.
Make sure notepad saves the file in UTF8 (encoding option is available in Save window)
#include <iostream>
#include <fstream>
#include <string>
#include <io.h>
#include <fcntl.h>
#include <Windows.h>
std::wstring u16(const std::string u8)
{
if (u8.empty()) return std::wstring();
int size = MultiByteToWideChar(CP_UTF8, 0, u8.c_str(), -1, 0, 0);
std::wstring u16(size, 0);
MultiByteToWideChar(CP_UTF8, 0, u8.c_str(), -1, u16.data(), size);
return u16;
}
int main()
{
(void)_setmode(_fileno(stdout), _O_U16TEXT);
std::string text;
std::ifstream fin("Info.txt");
if (fin)
while (getline(fin, text))
std::wcout << u16(text) << "\n";
return 0;
}