636: Mainline

Thus, you can have your main program ask for a file name, accept one, open it, check to be sure it is open, and pass the resulting input stream on to do_analysis, over and over, as follows:

main ( ) { 
  // Read file name and call analysis function repeatedly: 
  while (1) { 
    cout << "Please type the name of a train file." << endl << ": "; 
    cin >> input_buffer; 
    // Open: 
    ifstream car_stream (input_buffer); 
    // Check: 
    if (!car_stream) {cout << "No such file." << endl; return 0;} 
    // Analyze: 
    do_analysis (car_stream); 
    // Close 
    car_stream.close ( ); 
  } 
}