388: Mainline

Similarly, in the following program, you create an array that can hold up to 100 cylinders. Then, you fill part or all of it using a for reading pattern, and you use another for loop to add up the volumes, producing the total volume of the oil storage tanks:

#include   
const double pi = 3.14159; 
// Define the cylinder class: 
class cylinder { 
  public: double radius, length; 
          double volume ( ) {return pi * radius * radius * length;} 
}; 
// Define cylinder array: 
cylinder oil_tanks[100]; 
main ( ) { 
  // Declare various variables: 
  int limit, counter; 
  double radius, length, sum = 0.0; 
  // Read numbers and write them into array: 
  for (limit = 0; cin >> radius >> length; ++limit) { 
    oil_tanks[limit].radius = radius; 
    oil_tanks[limit].length = length; 
  } 
  // Compute volumes: 
  for (counter = 0; counter < limit; ++counter) 
    sum = sum + oil_tanks[counter].volume ( ); 
  // Display sum: 
  cout << "The total volume in the " 
       << limit << " storage tanks is " 
       << sum << endl; 
} 
--- Data ---
4.7       40.0 
3.5       35.5 
3.5       45.0       
--- Result --- 
The total volume in the 3 storage tanks is 5873.91