627: Mainline

Similar additions to the other car classes enable you to modify the class-object–creating for loop, as shown in the following version of the analyze_train program:

#include   
#include   
const double pi = 3.14159; 
// Box and cylinder class definitions go here 
class railroad_car { 
  public: char *serial_number; 
          railroad_car ( ) { } 
          // New constructor: 
          railroad_car (char *input_buffer) { 
            // Create new array just long enough: 
            serial_number = new char[strlen(input_buffer) + 1]; 
            // Copy string into new array: 
            strcpy (serial_number, input_buffer); 
          } 
          virtual char* short_name ( ) {return "rrc";} 
          virtual double capacity ( ) {return 0.0;} 
}; 
class box_car : public railroad_car, public box { 
  public: // Constructors: 
          box_car ( ) : box (10.5, 9.5, 40.0) { } 
          box_car (char *input_buffer) : railroad_car (input_buffer), 
                                         box (10.5, 9.5, 40.0) 
            { } 
          // Displayers: 
          virtual char* short_name ( ) {return "box";} 
          virtual double capacity ( ) {return volume ( );} 
}; 
// Other modified 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];} 
main ( ) { 
  int n, car_count; 
  // Read serial number and create car class objects: 
  for (car_count = 0; cin >> input_buffer; ++car_count) { 
    // Construct new class object: 
    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; 
      case tnk_code: 
        train[car_count] = new tank_car (input_buffer); break; 
      case cab_code: 
        train[car_count] = new caboose (input_buffer);  break; 
    } 
  } 
  // Display report: 
  for (n = 0; n < car_count; ++n) { 
    // Display short name and capacity and terminate the line:  
    cout << train[n] -> short_name ( ) 
         << "     " 
         << train[n] -> capacity ( ) 
         << endl; 
  } 
}