655: Mainline

In summary, you have the following version of analyze_train:

#include 
#include
#include
const double pi = 3.14159;
// Box and cylinder class definitions go here
class railroad_car {
  public: char *serial_number;
          // Constructors:
          railroad_car ( ) {++counter;}
          railroad_car (char *input_buffer) {
            ++counter;
            serial_number = new char[strlen(input_buffer) + 1]; 
            strcpy (serial_number, input_buffer);
          }
          // Destructor:
          virtual ~railroad_car ( ) {
             cout << "Destroying a railroad car; "
                  << --counter << " remain." << endl;
             delete [ ] serial_number;                          
          }
          // Other:
          virtual char* short_name ( ) {return "rrc";}
          virtual double capacity ( ) {return 0.0;}
  private: static int counter;
};
int railroad_car::counter = 0;
// Other railroad-car class definitions go here
railroad_car *train[100];
char input_buffer[100];
enum {eng_code = 'E', box_code = 'B', tnk_code = 'T', cab_code = 'C'};
char extract_car_code (char *input_buffer) {return input_buffer[4];}
void do_analysis (ifstream& car_stream) {
  int n, car_count;
  for (car_count = 0; car_stream >> input_buffer; ++car_count) {
    delete train[car_count];                                    
    switch (extract_car_code (input_buffer)) {
      case eng_code:
        train[car_count] = new engine (input_buffer); break;    
      case box_code:
        train[car_count] = new box_car (input_buffer); break;   
      // Entries for tank cars and cabooses 
    } 
  } 
  car_stream.close ( ); 
  for (n = 0; n < car_count; ++n)  
    cout << train[n] -> serial_number << "     " 
         << train[n] -> short_name ( ) << "     " 
         << train[n] -> capacity ( ) << endl; 
} 
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 the input file: 
    ifstream car_stream (input_buffer); 
    // Give up if the input file does not exist: 
    if (!car_stream) {cout << "No such file." << endl; return 0;} 
    // Analyze: 
    do_analysis (car_stream); 
    // Close: 
    car_stream.close ( ); 
  } 
}