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//Program to demonstrate call-by-reference parameters.
//Shows the difference between each of a list of golf scores and their average.
#include <iostream>
using namespace std;
const int MAX_NUMBER_SCORES = 10;
void fillArray(int a[], int size, int& numberUsed);
//Precondition: size is the declared size of the array a.
//Postcondition: numberUsed is the number of values stored in a.
//a[0] through a[numberUsed-1] have been filled with
//nonnegative integers read from the keyboard.
double computeAverage(const int a[], int numberUsed);
//Precondition: a[0] through a[numberUsed-1] have values; numberUsed > 0.
//Returns the average of numbers a[0] through a[numberUsed-1].
void showDifference(const int a[], int numberUsed);
//Precondition: The first numberUsed indexed variables of a have values.
//Postcondition: Gives screen output showing how much each of the first
//numberUsed elements of the array a differs from their average.
int main()
{
int score[MAX_NUMBER_SCORES], numberUsed;
cout << "This program reads golf scores and shows\n"
<< "how much each differs from the average.\n";
cout << "Enter golf scores:\n";
fillArray(score, MAX_NUMBER_SCORES, numberUsed);
showDifference(score, numberUsed);
return 0;
}
void fillArray(int a[], int size, int& numberUsed)
{
cout << "Enter up to " << size << " nonnegative whole numbers.\n"
<< "Mark the end of the list with a negative number.\n";
int next, index = 0;
cin >> next;
while ((next >= 0) && (index < size))
{
a[index] = next;
index++;
cin >> next;
}
numberUsed = index;
}
double computeAverage(const int a[], int numberUsed)
{
double total = 0;
for (int index = 0; index < numberUsed; index++)
total = total + a[index];
if (numberUsed > 0)
{
return (total / numberUsed);
}
else
{
cout << "ERROR: number of elements is 0 in computeAverage.\n"
<< "computeAverage returns 0.\n";
return 0;
}
}
void showDifference(const int a[], int numberUsed)
{
double average = computeAverage(a, numberUsed);
cout << "Average of the " << numberUsed
<< " scores = " << average << endl
<< "The scores are:\n";
for (int index = 0; index < numberUsed; index++)
cout << a[index] << " differs from average by "
<< (a[index] - average) << endl;
}
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