BubbleSort + Call by Ref + Call by Val CS311

#include <iostream>
using namespace std;
void swapnumbers (int &, int &);
void bubblesort (int arr[], int n)
{
    int i, j;
        for(i=n-1; i>0; i--)
            {
            for (j=0; j<i;j++)
                {
                if (arr[j] > arr[j+1])
                    {
                        int temp= arr[j+1];
                        arr[j+1]=arr[j];
                        arr[j]=temp;
                    }
                }
            }
}
void swapnumbers (int &A, int &B)
{
  int temp = B;
   B = A;
   A = temp;
}
void swapval (int x, int y)
{
   int temp = y;
   y = x;
   x = temp;

   return;
}

int main()
{
    cout<<"Bubble Sort\n";
    int array[20]= {1,2,5,6,3,7,6,8,9,3,6,4,7,3,7,5,4,8,5,9};
    int size = 20;
     bubblesort(array, size);
     for (int i = 0; i<20; i++)
        {
            cout<<array[i]<<" ";
        }
    cout<<"\n";
    cout<<"\n";
    cout<<"Call by Reference to Swap to Values\n";
    int a = 10;
    int b = 5;
    cout<<"Before Swap "<<a<<" "<<b;
    cout<<"\n";
    swapnumbers (a,b);
    cout<<"After Swap "<<a<<" "<<b;
    cout<<"\n";
     cout<<"\n";
    cout<<"Call by Value to Swap but not actually Swap\n";
     int x = 20;
    int y = 10;
    cout<<"Before Swap "<<x<<" "<<y;
    cout<<"\n";
    swapnumbers (a,b);
    cout<<"After Swap "<<x<<" "<<y;
    cout<<"\n";
    cout<<"\n";

    return 0;
}