Stacks (last-in, first-out) in Intro to Computing - Flowchart & Logic Diagram

Process Overview

A stack is a way to store items where the last item added is the first one to be taken out. Think of it like a stack of plates: you add plates on top and take plates from the top.

Flowchart

Rectangle

↓

Rectangle

Yes No↓

Rectangle

<-- Loop back to 'Push item onto stack?'↓

Rectangle

No Yes↓

Rectangle

↩<-- Loop back to 'Push item onto stack?'

Step-by-Step Trace - 7 Steps

Step 1: Start with an empty stack

Step 2: Push item 'A' onto the stack

Step 3: Push item 'B' onto the stack

Step 4: Push item 'C' onto the stack

Step 5: Pop item from the stack

Step 6: Pop item from the stack

Step 7: Pop item from the stack

Diagram

Top -> | C |
        | B |
        | A |
        -----
Bottom

This diagram shows the stack with 'C' on top, then 'B', then 'A' at the bottom. Items are added and removed from the top.

Flowchart Quiz - 3 Questions

If you push items A, B, then C onto an empty stack, which item will be popped first?

A A

B C

C B

D None, stack is empty

Key Result

A stack stores items so the last one added is always the first one removed, like a stack of plates.