mfc字符转码

std::wstring UTF8ToUnicode(const std::string& utf8string)

{
 int widesize = ::MultiByteToWideChar(CP_UTF8, 0, utf8string.c_str(), -1, NULL, 0);
 if (widesize == ERROR_NO_UNICODE_TRANSLATION)
 {
  throw std::exception("Invalid UTF-8 sequence.");
 }
 if (widesize == 0)
 {
  throw std::exception("Error in conversion.");
 }
 std::vector<wchar_t> resultstring(widesize);
 int convresult = ::MultiByteToWideChar(CP_UTF8, 0, utf8string.c_str(), -1, &resultstring[0], widesize);
 if (convresult != widesize)
 {
  throw std::exception("La falla!");
 }
 return std::wstring(&resultstring[0]);
}

std::string WideByteToAcsi(std::wstring& wstrcode)

{
 int asciisize = ::WideCharToMultiByte(CP_OEMCP, 0, wstrcode.c_str(), -1, NULL, 0, NULL, NULL);
 if (asciisize == ERROR_NO_UNICODE_TRANSLATION)
 {
  throw std::exception("Invalid UTF-8 sequence.");
 }
 if (asciisize == 0)
 {
  throw std::exception("Error in conversion.");
 }
 std::vector<char> resultstring(asciisize);
 int convresult = ::WideCharToMultiByte(CP_OEMCP, 0, wstrcode.c_str(), -1, &resultstring[0], asciisize, NULL, NULL);
 if (convresult != asciisize)
 {
  throw std::exception("La falla!");
 }
 return std::string(&resultstring[0]);
}

std::string UTF8ToASCII(std::string& strUtf8Code)

{
 std::string strRet("");
 //先把 utf8 转为 unicode   
 std::wstring wstr = UTF8ToUnicode(strUtf8Code);
 //最后把 unicode 转为 ascii   
 strRet = WideByteToAcsi(wstr);
 return strRet;
}

std::string ASCIIToUTF8(std::string& strASCIICode)

{
 std::string strOutUTF8 = "";
 WCHAR * str1;
 int n = MultiByteToWideChar(CP_ACP, 0, strASCIICode.c_str(), -1, NULL, 0);
 str1 = new WCHAR[n];
 MultiByteToWideChar(CP_ACP, 0, strASCIICode.c_str(), -1, str1, n);
 n = WideCharToMultiByte(CP_UTF8, 0, str1, -1, NULL, 0, NULL, NULL);
 char * str2 = new char[n];
 WideCharToMultiByte(CP_UTF8, 0, str1, -1, str2, n, NULL, NULL);
 strOutUTF8 = str2;
 delete[]str1;
 str1 = NULL;
 delete[]str2;
 str2 = NULL;
 return strOutUTF8;
}

//!!为了减少字符串的拷贝，改为使用shared_array，性能升级

#include <boost/shared_array.hpp>

#define CHAR_EMPTY_ARR_PTR boost::shared_array<char>(new char[1]{''})
#define WCHAR_EMPTY_ARR_PTR boost::shared_array<wchar_t>(new wchar_t[1]{L''})

boost::shared_array<char> UTF8ToASCII(std::string& strUtf8Code)

{
 return std::move(UTF8ToASCII(strUtf8Code.c_str()));
}

boost::shared_array<char> UTF8ToASCII(const char* ch, int nLen /*= -1*/)

{
 //先把 utf8 转为 unicode   
 auto wstr = UTF8ToUnicode(ch, nLen);
 //最后把 unicode 转为 ascii   
 return std::move(WideByteToAcsi(wstr.get()));
}

boost::shared_array<char> ASCIIToUTF8(std::string& strASCIICode)

{
 return std::move(ASCIIToUTF8(strASCIICode.c_str()));
}

boost::shared_array<char> ASCIIToUTF8(const char* ch, int nLen/* = -1*/)

{
 int n = MultiByteToWideChar(CP_ACP, 0, ch, nLen, NULL, 0);
 if (0 == n)
 {
  return CHAR_EMPTY_ARR_PTR;
 }
 boost::shared_array<wchar_t> ptrWtArr(new wchar_t[n]{ L'' });
 if (0 == MultiByteToWideChar(CP_ACP, 0, ch, nLen, ptrWtArr.get(), n))
 {
  return CHAR_EMPTY_ARR_PTR;
 }
 n = WideCharToMultiByte(CP_UTF8, 0, ptrWtArr.get(), -1, NULL, 0, NULL, NULL);
 if (0 == n)
 {
  return CHAR_EMPTY_ARR_PTR;
 }
 boost::shared_array<char> ptrArr(new char[n]{ '' });
 if (0 == WideCharToMultiByte(CP_UTF8, 0, ptrWtArr.get(), -1, ptrArr.get(), n, NULL, NULL))
 {
  return CHAR_EMPTY_ARR_PTR;
 }
 return std::move(ptrArr);
}

boost::shared_array<wchar_t> UTF8ToUnicode(const char* ch, int nLen /*= -1*/)

{
 int widesize = ::MultiByteToWideChar(CP_UTF8, 0, ch, nLen, NULL, 0);
 if (0 == widesize)
 {
  return WCHAR_EMPTY_ARR_PTR;
 }
 boost::shared_array<wchar_t> ptrWtArr(new wchar_t[widesize]{ L'' });
 int convresult = ::MultiByteToWideChar(CP_UTF8, 0, ch, nLen, ptrWtArr.get(), widesize);
 if (0 == convresult)
 {
  return WCHAR_EMPTY_ARR_PTR;
 }
 return std::move(ptrWtArr);
}
boost::shared_array<char> DPC::WideByteToAcsi(std::wstring& wstrcode)
{
 return std::move(WideByteToAcsi(wstrcode.c_str()));
}

boost::shared_array<char> WideByteToAcsi(const wchar_t* wch, int nLen /*= -1*/)

{
 int asciisize = ::WideCharToMultiByte(CP_OEMCP, 0, wch, nLen, NULL, 0, NULL, NULL);
 if (0 == asciisize)
 {
  return CHAR_EMPTY_ARR_PTR;
 }
 boost::shared_array<char> ptrArr(new char[asciisize + 1]{''});
 int convresult = ::WideCharToMultiByte(CP_OEMCP, 0, wch, nLen, ptrArr.get(), asciisize, NULL, NULL);
 if (0 == convresult)
 {
  return CHAR_EMPTY_ARR_PTR;
 }
 return std::move(ptrArr);
}