stof not working? (no main(), just used for fcns)

float option1() {
  //Option 1 shows the total precipitation for a single day, input of date

  float totalPRCP;
  reader.open("/Users/galenfleet/cpp/CS121Take3/temp/weather_station_five_column.txt");
  if(!reader) {
    cout << "We have a problem " << endl;
    return 1;
  }
  cout << "You Good" << endl;
  pause();
  cin.ignore();
  system("clear");

  cout << "Please input a date you waant to see [MM DD YYYY] " << endl;
  cin >> MM >> DD >> YY;
  cin.ignore();

  getline(reader, dataline);
  prcp = dataline.find("PRCP");
  date = dataline.find("DATE");
  while(getline(reader, dataline)) {
    if((dataline.substr(date, 4) == YY )&& (dataline.substr(date+5, 2) == MM) && (dataline.substr(date+8, 2) == DD)) {
      totalPRCP += stof(dataline.find(prcp, 4))
    }
  }
  reader.close();
  return totalPRCP;

}