// Zig Herzog
// Oct. 23, 2007
// Examples of passing one or multiple values back and forth using
// the method "pass-by-reference"
// If you run the program as shown below the cout statement will produce
// v1=10
//
// If you omit the & sign in "void ex1 ( int& )" and in "void ex1 ( int& v1 )"
// the program will still compile but the cout statement will produce :
// v1=2
//
// The task of example below could also have been accomplished using
// the method passing by value because only a single value needed to
// be returned to the calling function ( main() ).

#include <iostream>

using namespace std ;

void ex1 ( int& ) ;    //  <<<<  prototyping

int main () 
{
 
	int v1=2 ; 

	ex1 ( v1 ) ;   // <<<<< call to function ex1()

	cout << "v1=" << v1 << endl ;
}

//////////////  Definition of function ex1() ////////////////////////

void ex1 ( int& v1 )
{
	int factor = 5 ;    // this variable is local to function ex1().

	v1 = v1 * factor ;

}