1	#include <stream.h>
    2	
    3	void swap1(int x, int y);
    4	void swap2(int &x, int &y);
    5	void swap3(int *x, int *y);
    6		
    7	main()
    8	{
    9	    int i = 3;
   10	    int j = 4;
   11	
   12	    swap1(i , j);
   13	    cout << i << " " << j << "\n";
   14		
   15	    swap2(i , j);
   16	    cout << i << " " << j << "\n";
   17	
   18	    swap3(&i , &j);
   19	    cout << i << " " << j << "\n";
   20	}