#include <iostream>

using namespace std;


void Square( double & out, double x )                
{
   out = x * x;          // Store result in output variable      
}

int main(int argc, char ** argv )
{
   double a, b;

   a = 4.0;
   Square( b, a );       // b is passed by reference and can be modified by
                         // the method so that the result can be returned

   cout << "a = " << a << " --- squared = " << b << endl;
}