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Float

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Code Implementation

// DYNAMICALLY LINKED IMPLEMENTATION OF STACK 
Struct NodeType; 			//Forward declaration

class StackType
{
public: 
//Identical to previous implementation
private:
   NodeType* topPtr;
};
.
.
.
Struct NodeType 	
{
	ItemType  info;
	NodeType* next;
};







void StackType::Push ( ItemType newItem )
	// Adds newItem to the top of the stack.
{    
     if (IsFull())
     throw FullStack();
   NodeType*  location;
   location = new  NodeType;
   location->info = newItem;
   location->next = topPtr;
   topPtr = location;

}
Next

void StackType::Pop()		// Remove top item from Stack.
{
   if (IsEmpty())
	   throw EmptyStack();
   else
   {
	   NodeType* tempPtr;
      tempPtr = topPtr;
	   topPtr = topPtr ->next;
	   delete tempPtr;
   }
}

ItemType StackType::Top()  
// Returns a copy of the top item in the stack.
{
	if (IsEmpty())
	   throw EmptyStack();
   else
	   return topPtr->info;
}

Next

bool StackType::IsFull()  const
// Returns true if there is no room for another
// ItemType on the free store; false otherwise
{
	NodeType* location;
	try
	{
	   location = new NodeType;
	   delete location;
	   return false;
   }
   catch(std::bad_alloc exception)
   {
	   return true;
   }
}

When a local stack variable goes out of scope, the memory space for data member topPtr is deallocated. But the nodes that topPtr points to are not automatically deallocated.........NEED a DESTRUCTOR

stackType::~StackType()
// Post: stack is empty; 
// All items have been deallocated.
{
	NodeType* tempPtr;

	while (topPtr != NULL)
	{
	  tempPtr = topPtr;
	  topPtr = topPtr-> next;
	  delete tempPtr;
	}
}