CS210 Lab: Recursion Prelab

• pass by reference and pass by value (see CS 115 lab on pointers)
• deleting nodes in a linked list (see CS115 lab on linked list operations)

Prelab Questions:

1. Given the following piece of code, why aren't a and b exchanged after the call to exchange? (How could you modify the code?)

   void exchange(int, int);
   
   int main
   {
       int a=5,b=7;
      
       exchange(a,b);
   }
   
   void exchange (int x, int y)
   {
      int temp;
   
      temp = x;
      x = y;
      y = temp;
      return;
   } // end exchange
   		

2. What is the difference between ClearPtr and ClearPtr2 in the following code? Will both pointer and pointer2 be set to 0 after the calls to ClearPtr and ClearPtr2. Why/Why not?

   #include<iostream>
   using namespace std;
   
   void ClearPtr(int *&p);
   void ClearPtr2(int *p2);
   
   int main()
   {
   	int x=5, x2=6;
   	int *pointer, *pointer2;
   	
   	pointer=&x;
   	pointer2=&x2;
   	
   	cout << "x is: " << *pointer << endl;
   	cout << "pointer is holding address: " << pointer << endl;
   	cout << endl;
   	cout << "x2 is: " << *pointer2 << endl;
   	cout << "pointer2 is holding address: " << pointer2 << endl;
   	cout << endl;
   
   	ClearPtr(pointer);
   	ClearPtr2(pointer2);
   
   	cout <<"pointer is holding address: " << pointer << endl;
   	cout <<"pointer2 is holding address: " << pointer2 << endl;
   	
   
   	return 0;
   }
   
   void ClearPtr(int *& p)
   {
   	p=0;
   }
   
   void ClearPtr2(int *p2)
   {
   	p2=0;
   }