windows 使用 std::wofstream 写入文件。该文件仍然为空
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Wrote to a file using std::wofstream. The file remained empty
提问by Armen Tsirunyan
I wrote the following program using VS2008:
我使用 VS2008 编写了以下程序：
#include <fstream>
int main()
{
std::wofstream fout("myfile");
fout << L"???????? Россия ?sterreich Ελλ?δα ????" << std::endl;
}
When I tried to compile it the IDE asked me whether I wanted to save my source file in unicode, I said "yes, please".
Then I run the program, and myfile appeared in my project's folder. I opened it with notepad, the file was empty. I recalled that notepad supported only ASCII data. I opened it with WordPad, it was still empty. Finally the little genius inside me urged me to look at the file size and not surprisingly it was 0 bytes. So I rebuilt and reran the program, to no effect. Finally I decided to ask very intelligent people on StackOverflow as to what I am missing and here I am :)
当我试图编译它时，IDE 询问我是否想以 unicode 保存我的源文件，我说“是的，请”。
然后我运行程序，myfile 出现在我的项目文件夹中。我用记事本打开它，文件是空的。我记得记事本只支持 ASCII 数据。我用写字板打开它，它仍然是空的。最后，我内心的小天才催促我查看文件大小，毫不奇怪，它是 0 字节。所以我重建并重新运行程序，没有任何效果。最后，我决定在 StackOverflow 上询问非常聪明的人我错过了什么，我在这里:)
Edited:
编辑：
After the abovementioned intelligent people left some comments, I decided to follow their advice and rewrote the program like this:
在上述聪明人留下了一些评论后，我决定听从他们的建议，将程序改写成这样：
#include <fstream>
#include <iostream>
int main()
{
std::wofstream fout("myfile");
if(!fout.is_open())
{
std::cout << "Before: Not open...\n";
}
fout << L"???????? Россия ?sterreich Ελλ?δα ????" << std::endl;
if(!fout.good())
{
std::cout << "After: Not good...\n";
}
}
Built it. Ran it. And... the console clearly read, to my surprise: "After: Not good...". So I edited my post to provide the new information and started waiting for answers which would explain why this is and what I could do. :)
建造了它。跑了 而且……控制台清楚地读到，令我惊讶的是：“之后：不好……”。所以我编辑了我的帖子以提供新信息并开始等待答案，这些答案可以解释为什么会这样以及我可以做什么。:)
采纳答案by Artyom
In Visual studio the output stream is always written in ANSI encoding, and it does not support UTF-8 output.
在 Visual Studio 中，输出流始终以 ANSI 编码编写，并且不支持 UTF-8 输出。
What is basically need to do is to create a locale class, install into it UTF-8 facet and then imbue it to the fstream.
基本上需要做的是创建一个语言环境类，将 UTF-8 facet 安装到其中，然后将其注入 fstream。
What happens that code points are not being converted to UTF encoding. So basically this would not work under MSVC as it does not support UTF-8.
代码点未转换为 UTF 编码会发生什么情况。所以基本上这在 MSVC 下不起作用，因为它不支持 UTF-8。
This would work under Linux with UTF-8 locale
这将在使用 UTF-8 语言环境的 Linux 下工作
#include <fstream>
int main()
{
std::locale::global(std::locale(""));
std::wofstream fout("myfile");
fout << L"???????? Россия ?sterreich Ελλ?δα ????" << std::endl;
}
~ And under windows this would work:
〜在Windows下这将起作用：
#include <fstream>
int main()
{
std::locale::global(std::locale("Russian_Russia"));
std::wofstream fout("myfile");
fout << L"Россия" << std::endl;
}
As only ANSI encodings are supported by MSVC.
因为 MSVC 只支持 ANSI 编码。
Codecvt facet can be found in some Boost libraries. For example: http://www.boost.org/doc/libs/1_38_0/libs/serialization/doc/codecvt.html
Codecvt facet 可以在一些 Boost 库中找到。例如：http: //www.boost.org/doc/libs/1_38_0/libs/serialization/doc/codecvt.html
回答by DerKuchen
MSVC offers the codecvt_utf8locale facet for this problem.
MSVCcodecvt_utf8为这个问题提供了语言环境方面。
#include <codecvt>
// ...
std::wofstream fout(fileName);
std::locale loc(std::locale::classic(), new std::codecvt_utf8<wchar_t>);
fout.imbue(loc);
