//Tests the procedure bubsort.
#include <iostream.h>

const int TRUE=1, FALSE=0;

void fill_array(int a[], int size, int& number_used);
//Precondition: size is the declared size of the array a.
//Postcondition: number_used is the number of values stored in a.
//a[0] through a[number_used - 1] have been filled with
//nonnegative integers read from the keyboard.

void bubsort(int a[], int number_used);
//Precondition: number_used <= declared size of the array a.
//The array elements a[0] through a[number_used - 1] have values.
//Postcondition: The values of a[0] through a[number_used - 1] have
//been rearranged so that a[0] <= a[1] <= ... <= a[number_used - 1].
//The algorithm is `bubble sort'.

void swap_values(int& v1, int& v2);
//Interchanges the values of v1 and v2.

int main( )
{   int sample_array[10], number_used;

    cout << "This program sorts numbers from lowest to highest.\n";

    fill_array(sample_array, 10, number_used);
    bubsort(sample_array, number_used);

    cout << "In sorted order the numbers are:\n";
    for (int index = 0; index < number_used; index++)
        cout << sample_array[index] << " ";
    cout << endl;

    return 0;
}

//Uses iostream.h:
void fill_array(int a[], int size, int& number_used)
{
    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;
    }

    number_used = index;
}

void bubsort(int a[], int number_used)
{   int times = 0, exchange=TRUE, current;

    while ((times < number_used - 1)&&(exchange))
    {     exchange = FALSE;
          for (current = 0; current < number_used-1-times; current++)
           {if (a[current] > a[current+1])
            {swap_values(a[current], a[current+1]);
             exchange = TRUE;};};
          times++;
    }
}


void swap_values(int& v1, int& v2)
{
    int temp;
    temp = v1;
    v1 = v2;
    v2 = temp;
}