static std::string w2c(std::wstring str)	{		int nlength = str.length();		int nbytes = WideCharToMultiByte(0,0,str.c_str(),nlength,NULL,0,NULL,NULL);		if(nbytes == 0) return "";		char*buff = new char[nbytes+1];		WideCharToMultiByte(0,0,str.c_str(),nlength,buff,nbytes,NULL,NULL);		buff[nbytes] = '\0';		std::string ret_str = std::string(buff);		delete [] buff;		return ret_str;			}static std::wstring c2w(std::string str)	{		if(str.length() == 0) return std::wstring();		int nu = str.length();		size_t n =(size_t)MultiByteToWideChar(CP_ACP,0,str.c_str(),nu,NULL,0);		wchar_t*wbuff = new wchar_t[n+1];		MultiByteToWideChar(CP_ACP,0,str.c_str(),(int)nu,wbuff,(int)n);		wbuff[n] = 0;		std::wstring wstr_ret = std::wstring(wbuff);		delete []wbuff;		return wstr_ret;	}