// this program asks the user to enter integer values 
// into an array, sorts the array, and prints out
// the sorted array and the average of all values in 
// the array.
//
// This is almost identical to bubblesort2.cpp, except 
// that it uses a slightly different version of the 
// print_int_array function.

#include <stdio.h>
#include <stdlib.h>

// sorts the array n in ascending order of its elements.
// length is the number of elements in the array n.
void bubblesort(int * n, int length)
{
  int number_of_passes = 0;
  while(1)
  {
    number_of_passes++;
    int changes_made = 0;
    int i;
    for (i = 0; i < length-1; i++)
    {
      if (n[i] > n[i+1])
      {
        int temporary = n[i];
        n[i] = n[i+1];
        n[i+1] = temporary;

        changes_made = 1;
      }
    }

    if (changes_made == 0)
    {
      break;
    }
  }

  printf("%d passes were made\n", number_of_passes);
}


// prints the elements of the array n. See bubblesort1 
// for an alternative version of this function.
// length is the number of elements in the array n.
void print_int_array(int * a, int length)
{
  int i;
  for (i = 0; i < length; i++)
  {
    printf("a[%d] = %d\n", i, a[i]);
  }
}


// computes the average value of all elements in the array n.
// length is the number of elements in the array n.
double array_mean(int * a, int length)
{
  int i;
  int sum = 0;

  for (i = 0; i < length; i++)
  {
    sum = sum + a[i];
  }

  double sum2 = (double) sum;
  double length2 = (double) length;

  return sum2 / length2;
}


int main()
{
  int length;
  printf("how many numbers do you want to enter?\n");
  scanf("%d", &length);

  // create an array of ints. The number of elements
  // in the array is specified by the value of length
  // (which was specified by the user)
  int * numbers = (int *) malloc(sizeof(int) * length);
  
  // ask the user to enter a value for each element in the array.
  int i;
  for (i = 0; i < length; i++)
  {
    printf("please enter a value for element %d:\n", i);
    scanf("%d", &numbers[i]);
  }

  // print the array before sorting.
  printf("\nbefore sorting:\n");
  print_int_array(numbers, length);

  // sort the array
  bubblesort(numbers, length);

  // print the array after sorting
  printf("\nafter sorting:\n");
  print_int_array(numbers, length);

  // compute and print the average value in the array.
  double mean = array_mean(numbers, length);
  printf("the average value is %lf\n", mean);

  // for every array that we create with malloc, we must
  // destroy with free, when we don't need the array anymore.
  free(numbers);
}