// FILE: CmpSmAvN.cpp
// COMPUTES AND PRINTS THE SUM AND AVERAGE OF A COLLECTION OF DATA
//    ITEMS

#include <iostream.h>
#include <iomanip.h>

// Functions used ...
// COMPUTES SUM OF DATA
double compute_sum
  (int);			// IN: number of data items

// COMPUTES AVERAGE OF DATA
double compute_ave
  (int,				// IN: number of data items
   double);			// IN: sum of data items

// PRINTS NUMBER OF ITEMS, SUM, AND AVERAGE
void print_sum_ave
  (int,				// IN: number of data items
   double,			// IN: sum of the data
   double);			// IN: average of the data

int main ()
{
   // Local data ...
   int num_items;		// input: number of items to be added
   double sum;		// output: accumulated sum of data
   double average;	// output: average of data being processed

   // Read the number of items to process.
   cout << "Enter the number of items to process:";
   cin >> num_items;

   // Compute the sum of the data.
   sum = compute_sum (num_items);

   // Compute the average of the data.
   average = compute_ave (num_items, sum);

   // Print the sum and the average.
   print_sum_ave (num_items, sum, average);

   return 0;
}
// Insert definitions for functions compute_sum, compute_ave,
//   and print_ave here.

// COMPUTES SUM OF DATA
double compute_sum
  (int num_items)		// IN: number of data items
// Pre:  num_items is assigned a value.
// Post: num_items data items read; their sum is stored in sum.
// Returns: Sum of all data items read if num_items >= 1;
//ÊÊÊÊotherwise 0.0.
{
   // Local data ...
   double item;		// input: contains current item being added
   double sum;		// output: used to accumulate sum of data
				// ÊÊÊÊÊÊÊÊitems read

   // Read each data item and accumulate it in sum.
   sum = 0.0;
   for (int count = 0; count < num_items; count++)
    {
      cout << "Enter a number to be added: ";
      cin >> item;
      sum += item;
   }  // end for
   return sum;
}  // end compute_sum

// COMPUTES AVERAGE OF DATA
double compute_ave
  (int num_items,		// IN: number of data items
   double sum)			// IN: sum of data
// Pre:  num_items and sum are defined; num_items must be
//       greater than 0.
// Post: If num_items is positive, the average is computed as
//       sum / num_items;
// Returns: The average if num_items is positive; otherwise, 0.
{
   // Compute the average of the data.
   if (num_items < 1)				// test for invalid input
   {
      cout << "Invalid value for num_items = " << num_items
           << endl;
      cout << "Average not computed." << endl;
      return 0.0;					// return for invalid input
   }  // end if
   return sum / double (num_items);	// recast operand num_items
}  // end compute_ave

// PRINTS NUMBER OF ITEMS, SUM, AND AVERAGE OF DATA
void print_sum_ave
  (int num_items,		// IN: number of data items
   double sum,			// IN: sum of the data
   double average)		// IN: average of the data
// Pre:  num_items, sum, and average are defined.
// Post: Displays num_items, sum and average if num_items > 0.
{
   // Display results if num_items is valid.
   if (num_items > 0)
   {
      cout.precision (2);
      cout.setf (ios::fixed);
      cout << "The number of items is " << num_items << endl;
      cout << "The sum of the data is " << sum << endl;
      cout << "The average of the data is " << average << endl;
   }
   else
   {
      cout << "Invalid number of items = " << num_items << endl;
      cout << "Sum and average are not defined." << endl;
      cout << "No printing done.  Execution terminated." << endl;
   }  // end if
}  // end print_sum_ave