/* Program to process exam grades - illustrate use of EOF detection */
#include <iostream>
#include <fstream>
#include <cstdlib>          //needed to use exit() function
using namespace std;

const int SIZE = 50;

/* Function Prototypes */
void readdata(int [], int &);
int sumarray(int [], int);
double avgarray(int [], int);
int findmax(int [], int);
void countmarks(int [], int, double, int &, int &, int &);

int main()
{
    int num;
    int mark[SIZE];
    double avgmark;
    int numabove,numbelow,numequal,hi_mark;

    // call function to read the marks
    readdata(mark,num);

    // print the mark array
    cout << endl << endl << "The values of the array are:" << endl;
    for (int count = 0; count < num; count++)
        cout << "mark[" << count << "]=" << mark[count] << endl;

    // find and print the average mark
    avgmark = avgarray(mark,num);
    cout << endl << "The average is " << avgmark << endl;

    // find and print the highest mark
    hi_mark = findmax(mark,num);
    cout << "The highest mark is " << hi_mark << endl;

    // classify marks w.r.t. average mark
    countmarks(mark,num,avgmark,numbelow,numabove,numequal);
    cout << "Number of marks below the average is " << numbelow << endl;
    cout << "Number of marks above the average is " << numabove << endl;
    cout << "Number of marks equal to the average is " << numequal << endl;

//  system("pause");    //un-comment when using DevC++
    return 0;
}

/* Function sumarray()
 * Input:
 *  numbers - an array of integers
 *  n - the number of elements in the array
 * Process:
 *  finds the sum of the first n elements in the numbers array.
 * Output:
 *  returns the sum to the calling function.
 */
int sumarray(int numbers[], int n)
{
    int sum=0;

    for (int count = 0; count < n; count++)
        sum += numbers[count];
    return(sum);
}

/* Function avgarray()
 * Input:
 *  numbers - an array of integers
 *  n - the number of elements in the array
 * Process:
 *  calls sumarray to find the sum of the first n elements
 *  and then divides by n to find the average.
 * Output:
 *  returns the average to the calling function.
 */
double avgarray(int numbers[], int n)
{
    return ((double)sumarray(numbers,n)/n);
}

/* Function readdata()
 * Input:
 *  numbers - an array to be filled
 *  n - a reference to the number of elements in the array
 *  the parameters are uninitialized upon entry
 * Process:
 *  reads values into the array until EOF encountered
 *  and counts how many are read
 * Output:
 *  the filled numbers array
 *  n - the number of elements in the array
 */
void readdata(int numbers[], int &n)
{
    //un-comment to redirect cin to a file
    //ifstream cin("c:\\bc\\CISC1110\\pgms\\chapter7\\myinput.txt");

    // read and count number of marks
    n = 0;
    cout << "Enter the marks - end with EOF: " << endl;

    while (cin >> numbers[n])
        n++;

    if (n > 0 && n <= SIZE)
        cout << endl << endl << "There are " << n << " marks" << endl;
    else
    {
        cout << "Invalid number of marks" << endl;
//      system("pause");    //un-comment when using DevC++
        exit(1);
    }

    return;
}

/* Function findmax()
 * Input:
 *  numbers - an array of integers
 *  n - the number of elements in the array
 * Process:
 *  finds the largest value in the array
 * Output:
 *  returns the maximum value within the array
 */
int findmax(int numbers[], int n)
{
    int largest_so_far;

    largest_so_far = numbers[0];
    for (int count = 1; count < n; count++)
    if (largest_so_far < numbers[count])
        largest_so_far = numbers[count];
    return(largest_so_far);
}

/* Function countmarks()
 * Input:
 *  numbers - an array of integers
 *  n - the number of elements in the array
 *  avgnum - the average value of the array elements
 *  num_below - a reference to the number of elements of
 *      the array that are below the average
 *  num_above - a reference to the number of elements of
 *      the array that are above the average
 *  num_equal - a reference to the number of elements of
 *      the array that equal to the average
 * Process:
 *  counts the number of elements that are above, below,
 *  and equal to avgnum.
 * Output:
 *  num_below - the number of elements below average
 *  num_above - the number of elements above average
 *  num_equal - the number of elements equal to the average
 */
void countmarks(int numbers[], int n, double avgnum,
    int &num_below, int &num_above, int &num_equal)
{
    num_below = num_above = num_equal = 0;          //initialize the counters

    for (int count = 0; count < n; count++)
        if ((double)numbers[count] < avgnum)
            num_below++;
        else if ((double)numbers[count] > avgnum)
            num_above++;
        else
            num_equal++;
    return;
}