639: Mainline

Assembling all file-handling elements into a new program, you have the following:

#include   
#include 
#include 
const double pi = 3.14159; 
// 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) { 
  // Declare various integer variables: 
  int n, car_count; 
  // Read serial number and create car class objects: 
  for (car_count = 0; car_stream >> 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 here 
} 
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 ( ); 
  } 
}