C++ 从 txt 文件中读取 UTF-8（立陶宛字母）符号并在控制台应用程序中显示它们

Question

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;
}