Stack Data Type (5.1)

















What's a Stack?


	1. a List with restricted access
	2. only the top item on the stack is accessible
	3. LIFO (Last In First Out)
	4. items come out in reverse order

















What operations are supported by a Stack?
What's the abstract interface for a Stack?


	push(item);
	pop();
	top();
	empty();

















Classwork
You may work with a partner.

What does the program print?

	Stack S1;
	S1.push(4);
	S1.push(2);
	S1.push(4);
	S1.push(8);
	print(S1);

	Stack S2;
	Stack S3;
	while (!S1.empty()) {
	    S2.push(S1.pop());
	    S3.push(S1.pop());
	}
	print(S2);
	print(S3);

	while (!S2.empty())
	    S3.push(S2.pop());
	print(S3);

















What kinds of applications is a Stack good for?
What kinds of problems can be solved using a Stack?


	nested data

	data with a reversing nature

















Stacks in the C++ Library


	#include <stack>

	std::stack

















What are some of the operations supported by std::stack?


	void push ( const ItemType& item );
	void pop ( );  // does not return the popped item
	ItemType& top ( );
	bool empty () const;
	size_t size() const;