将wstring转换为以UTF-8编码的字符串

问题描述

我需要在wstring和string之间转换。我想，使用codecvt facet应该做的伎俩，但它似乎并不适用于utf-8区域。

I need to convert between wstring and string. I figured out, that using codecvt facet should do the trick, but it doesn't seem to work for utf-8 locale.

我的想法是，当我阅读utf-8编码的文件到字符，一个utf-8字符读入两个正常字符（这是utf-8的工作原理）。我想从我的代码中使用的库的wstring表示创建这个utf-8字符串。

My idea is, that when I read utf-8 encoded file to chars, one utf-8 character is read into two normal characters (which is how utf-8 works). I'd like to create this utf-8 string from wstring representation for library I use in my code.

有没有人知道怎么做？

我已经尝试过了：

  locale mylocale("cs_CZ.utf-8");
  mbstate_t mystate;

  wstring mywstring = L"čřžýáí";

  const codecvt<wchar_t,char,mbstate_t>& myfacet =
    use_facet<codecvt<wchar_t,char,mbstate_t> >(mylocale);

  codecvt<wchar_t,char,mbstate_t>::result myresult;

  size_t length = mywstring.length();
  char* pstr= new char [length+1];

  const wchar_t* pwc;
  char* pc;

  // translate characters:
  myresult = myfacet.out (mystate,
      mywstring.c_str(), mywstring.c_str()+length+1, pwc,
      pstr, pstr+length+1, pc);

  if ( myresult == codecvt<wchar_t,char,mbstate_t>::ok )
   cout << "Translation successful: " << pstr << endl;
  else cout << "failed" << endl;
  return 0;

对cs_CZ.utf-8区域设置返回failed，并对cs_CZ.iso8859-2 locale。

which returns 'failed' for cs_CZ.utf-8 locale and works correctly for cs_CZ.iso8859-2 locale.

推荐答案

C ++不知道Unicode。使用外部库（例如ICU）（）或Qt（），都支持Unicode，包括UTF-8。

C++ has no idea of Unicode. Use an external library such as ICU (UnicodeString class) or Qt (QString class), both support Unicode, including UTF-8.

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