C++：有关单双字节字串转换及编码转换

单双字节字串转换示例：

//单(string)->双字节(CString)字串
void doSomething(string aStr) {
  USES_CONVERSION;
  LPCTSTR x = A2CT(aStr.c_str());
  CString xx = x;
  ...
}

//双(CString)->单字节(string)字串
void doSomething(CString tStr) {
  USES_CONVERSION;
  LPCSTR x = T2CA(tStr);
  string xx = x;
  ...
}

编码转换函数：

#define STACK_ARRAY(TYPE, LEN) static_cast(alloca(LEN * sizeof(TYPE)))

inline std::wstring MutiBytesToCodePage(const std::string& str, UINT CodePage) {
  int len16 = ::MultiByteToWideChar(CodePage, 0, str.data(), (int)str.length(), NULL, 0);
  wchar_t *ws = STACK_ARRAY(wchar_t, len16);
  ::MultiByteToWideChar(CodePage, 0, str.data(), (int)str.length(), ws, len16);
  std::wstring result(ws, len16);
  return result;
}
inline std::wstring ToUtf16(const std::string& str) {
  return MutiBytesToCodePage(str, CP_UTF8);
}
inline std::wstring ToSystemCodePage(const std::string& str) {
  return MutiBytesToCodePage(str, CP_UTF8);
}

inline std::string WstrToCodePage(const std::wstring& wstr, UINT CodePage) {
  int len8 = ::WideCharToMultiByte(CodePage, 0, wstr.data(), (int)wstr.length(), NULL, 0, NULL, NULL);
  char* ns = STACK_ARRAY(char, len8);
  ::WideCharToMultiByte(CodePage, 0, wstr.data(), (int)wstr.length(), ns, len8, NULL, NULL);
  std::string result(ns, len8);
  return result;
}
inline std::string ToUtf8(const std::wstring& wstr) {
  return WstrToCodePage(wstr, CP_UTF8);
}
inline std::string ToSystemCodePage(const std::wstring& wstr) {
  return WstrToCodePage(wstr, CP_ACP);
}

调用示例：

void doSomething(string aStr) {
  wstring x = MutiBytesToCodePage(aStr, CP_UTF8);
  CString xx = xx.c_str();
  ...
}