Stacks

Question 1

What is a stack?

Answer 1

A stack is like a stack of plates. The last item put on, is the first one to be removed (last in first out - LIFO). A stack uses a single pointer to the top of the stack. You can add items (push) and remove items (pop) to/from stacks).

Question 2

What are uses of stacks?

Answer 2

• Back/forward button on browsers
• Undo operations

Question 3

How to add data to a stack?

Answer 3

stack.push() - points to the next free space, adds the item and increments the stacker pointer

Question 4

How to remove data from a stack?

Answer 4

stack.pop() - decrements the stack pointer and returns the item at the top of the stack

Question 5

How are stacks implemented in code?

Answer 5

1. Using a procedural approach - Define an array and pointer variable, and write functions/procedures to pop/push items.
2. Using built in functionality from libraries - Use the built in stack class provided by a library
3. Using an object oriented approach - Define your own stack class