为什么文件名有UTF16转换后不同的字节 - ＆GT; UTF8 - ＆GT; UTF16在WINAPI？ [英] Why filename has different bytes after converting UTF16 -> UTF8 -> UTF16 in winapi?

问题描述

我有一个文件：

我使用 ReadDirectoryChangesW 当前文件夹中阅读的变化。
而我得到此文件路径：LTESTӠ⬨☐.ipt

I use ReadDirectoryChangesW for reading changes in current folder. And I get path to this file: L"TEST Ӡ⬨☐.ipt":

接下来，我想将其转换为UTF8和背部：

Next, I want to convert this to utf8 and back:

std::string wstringToUtf8(const std::wstring& source) {
  const int size = WideCharToMultiByte(CP_UTF8, 0, source.data(), static_cast<int>(source.size()), NULL, 0, NULL, NULL);
  std::vector<char> buffer8(size);
  WideCharToMultiByte(CP_UTF8, 0, source.data(), static_cast<int>(source.size()), buffer8.data(), size, NULL, NULL);
}

std::wstring utf8ToWstring(const std::string& source) {
  const int size = MultiByteToWideChar(CP_UTF8, 0, source.data(), static_cast<int>(source.size()), NULL, 0);
  std::vector<wchar_t> buffer16(size);
  MultiByteToWideChar(CP_UTF8, 0, source.data(), static_cast<int>(source.size()), buffer16.data(), size);
}

int main() {
    // Some code with ReadDirectoryChangesW and 
    // ...
    // std::wstring fileName = "L"TEST Ӡ⬨☐.ipt""
    // ...

    std::string filenameUTF8 = wstringToUtf8(fileName);
    std::wstring filename2 = utf8ToWstring(filenameUTF8);
    assert(filenameUTF8 == filename2); // FAIL!
    return 0;
}

但我赶上断言。
文件名2：

不同位：[29]

为什么？

推荐答案

57216似乎下降到代理对范围内，UTF-16使用EN code非BMP code点。他们需要成对给予，或解码不会给你正确的$ C $连接点。

57216 seems to fall in to surrogate pair range, used in UTF-16 to encode non-BMP code points. They need to be given in pairs, or decoding won't give you correct codepoint.

65533是一个特殊的错误特性而德codeR给人因为其他替代缺失。

65533 is a special error character which decoder gives because other surrogate is missing.

要换个说法：你原来的字符串是无效的UTF-16字符串

To put it another way: Your original string is not valid UTF-16 string.

更多信息。

More info on Wikipedia.

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