c++ 截取字符串

void  RoomTool::CalculateRoomNum(string strRoomNum, string &strRoom)
{
	string strRoomT = strRoomNum;
	string strTemp = "";
	char cp = ',';

	int i = 0;
	while (true)
	{
		i++;
		int iLocation = strRoomT.find(cp, 0);
		strRoomT = strRoomT.substr(iLocation + 1);

		if (i == 4)
		{
			strTemp = strRoomT;
		}

		if (i == 5)
		{
			strRoom = strTemp.substr(0, iLocation);
			break;
		}
	}
}

string strSrc = "234D833A78,1,2,10,10101,3,2007-10-10 12:20:00,2007-10-11 12:00:00,1";

截取10101字符串