// Copyleft: Sathiamoorthy Manoharan.

#include <iostream>

// Passing by value means passing a copy of the object.
// This version of Swap passes n1 and n2 by value (i.e. copy of the
// objects 'a' and 'b' are passed in as 'n1' and 'n2'. 
// Changes to 'n1' and 'n2' inside the method do not
// change the original objects 'a' and 'b'.
int
SwapV1(int n1, int n2)
{
   int temp = n1;
   n1 = n2;
   n2 = temp;
} // SwapV1

// Passing by reference means passing the object itself.
// This version of Swap passes n1 and n2 by reference (i.e. the
// objects 'a' and 'b' are passed, though they are named 'n1' and
// 'n2' within the method.
int
SwapV2(int& n1, int& n2)
{
   int temp = n1;
   n1 = n2; 
   n2 = temp;
} // SwapV2

int
main()
{
   int a = 34, b = 86;
   std::cout << "Initial values:\n";
   std::cout << "a: " << a << " b: " << b << "\n";

   SwapV1(a, b);
   std::cout << "After SwapV1:\n";
   std::cout << "a: " << a << " b: " << b << "\n";

   SwapV2(a, b);
   std::cout << "After SwapV2:\n";
   std::cout << "a: " << a << " b: " << b << "\n";

   return 0;
}