// Comparing call-by-value and call-by-reference 
// with references.
#include <iostream.h>

int squareByValue(int);
void squareByReference(int &);

main()
{
   int x = 2, z = 4;

   cout << "x = " << x << " before squareByValue" << endl
        << "Value returned by squareByValue: "
        << squareByValue(x) << endl
        << "x = " << x << " after squareByValue" << endl << endl;

   cout << "z = " << z << " before squareByReference" << endl;
   squareByReference(z);
   cout << "z = " << z << " after squareByReference" << endl;

   return 0;
}

int squareByValue(int a)
{
   return a *= a;   // caller's argument not modified
}

void squareByReference(int &cRef)
{
   cRef *= cRef;    // caller's argument modified
}