#include <iostream>
using namespace std;

void PtrByValue(int* APtr, int* BPtr)
{
   cout <<"In function:"<<endl;

   int tempPtr = *APtr;
   *APtr = *BPtr;
   *BPtr = tempPtr;

   cout << &APtr <<" "<< &BPtr <<endl;
   cout << *APtr <<" "<< *BPtr <<endl;
   cout <<"End function:"<<endl;
}

void PtrByRef( int* &APtr, int* &BPtr )
{
    int* TempPtr = APtr;
    APtr = BPtr;
    BPtr = TempPtr; 
}

int main()
{
   int* ptr1 = NULL;
   int* ptr2 = NULL;

   int a = 4;
   int b = 6;

   ptr1 = &a;
   ptr2 = &b;

   cout << ptr1 <<" "<< ptr2 <<endl;
   cout << *ptr1 <<" "<< *ptr2 <<endl;
   //PtrByValue( ptr1, ptr2 );
   PtrByRef( ptr1, ptr2 );
   cout << ptr1 <<" "<< ptr2 <<endl;
   cout << *ptr1 <<" "<< *ptr2 <<endl;
}