558: Mainline

The following program is stripped down to a few essentials so as to illustrate the speed-up and argument-altering properties of call-by-reference parameters without the complexity involved in reading information and producing a report:

#include   
// Class definitions; container class includes percent_loaded 
// Define ordinary functions: 
double slow_floor_space_function (box_car b) { 
  return b.width * b.length; 
} 
double fast_floor_space_function (box_car& b) { 
  return b.width * b.length; 
} 
void defective_loading_function (box_car b) { 
  b.percent_loaded = 100; 
  return; 
} 
void working_loading_function (box_car& b) { 
  b.percent_loaded = 100; 
  return; 
} 
main ( ) { 
  box_car typical_box_car; 
  cout << "                     Slow    Fast" << endl 
       << "Area computations:   " 
       << slow_floor_space_function (typical_box_car) 
       << "     " 
       << fast_floor_space_function (typical_box_car) 
       << endl; 
  typical_box_car.percent_loaded = 0; 
  cout << "                                          Percent Loaded" 
       << endl; 
  cout << "Before calling either loading function:   " 
       << typical_box_car.percent_loaded 
       << endl; 
  defective_loading_function (typical_box_car);   
  cout << "After calling defective_loading_function: " 
       << typical_box_car.percent_loaded 
       << endl; 
  working_loading_function (typical_box_car); 
  cout << "After calling working_loading_function:   " 
       << typical_box_car.percent_loaded 
       << endl; 
} 
--- Result --- 
                     Slow    Fast 
Area computations:   380     380 
                                          Percent Loaded 
Before calling either loading function:   0 
After calling defective_loading_function: 0 
After calling working_loading_function:   100