484: Mainline

The following revised version of the analyze_train program replaces if-else statements with a switch statement, includes error handling, and exploits enumeration constants:

#include   
#include   
// Railroad car class definitions go here 
// Define railroad car pointer array: 
railroad_car *train[100]; 
// Declare enumeration constants, needed in switch statement: 
enum {eng_code, box_code, tnk_code, cab_code}; 
main ( ) { 
  // Declare various integer variables: 
  int n, car_count, type_code; 
  // Read car-type number and create car class objects: 
  for (car_count = 0; cin >> type_code; ++car_count) 
    switch (type_code) { 
      case eng_code: train[car_count] = new engine;   break; 
      case box_code: train[car_count] = new box_car;  break; 
      case tnk_code: train[car_count] = new tank_car; break; 
      case cab_code: train[car_count] = new caboose;   break; 
      default: cerr << "Car code " << type_code 
                    << " is unknown!" << endl;  
               exit (0); 
    } 
  // Display classes using display_short_name virtual function: 
  for (n = 0; n < car_count; ++n) { 
    train[n] -> display_short_name ( ); 
    cout << endl; 
  } 
} 
--- Data ---
0 1 1 2 3  
--- Result --- 
eng 
box 
box 
tnk 
cab