Exercise 4.3 E2

E2. What is wrong with the following attempt to use the copy constructor to implement the overloaded assignment operator for a linked Stack?

void Stack::operator=(const Stack&original)
{
 Stack new_copy(original);
 top_node=new_copy.top_node;
}

How can we modify this code to give a correct implementation?

 

正解：

void Stack::operator=(const Stack&original)
{
 Node*new_top,*new_copy,*original_node=original.top_node;
 if(original_node==NULL)
  new_top=NULL;
 else
 {
  new_copy=new_top=new Node(origanal_node->entry);
  while(original_code->NULL)
  {
   original_node=original_node->next;
   new_copy->next=new Node(original_node->entry);
   cew_copy=new_copy->next;
  }
 }
 while(!empty())
  pop();
 top_node=new_top;
}