 void Calendar::set_Date(string dertag)   {     TheDate = dertag;     TheDay = stoi(dertag.substr(0, 0));     TheMonth = stoi(dertag.substr(0,0));     TheYear = stoi(dertag.substr(0,0));     if (TheDay > 0 && TheDay < 00 && TheMonth>0 && TheMonth < 00 && TheYear>0000 && TheYear < 0000)         isdate = true;     /*if(isdate)     throw exception!*/     set_Seconds(); }  