• Stacks:
  • Drink Shelves at Convenience Stores
  • Trucks/Containers/Boxcars
• Queues:
  • "Checkout" Lines
  • Toll Booths

• Stacks:
  • Activation Records/Call Stack
  • Undo Stack
• Queues:
  • Process/Thread Queue
  • Event Queue
  • Print Queue

• Different Notations:
  • Infix: 5 + 3
  • Prefix: + 5 3
  • Postfix: 5 3 +
• Complex Postfix Expressions:
  1. Choose any group: operand1 operand2 operator
  2. Evaluate that group
  3. Replace the group with its evaluation
  4. Repeat

3 4 * 8 7 3 - / / 4 +

while (moreTokens)
{
    token = nextToken()
    if (token isa number)
    {
        push(token)
    }
    else
    {
        operand2 = pop()
        operand1 = pop()
        result = operand1 token operand2
        push(result)
    }
}
answer = pop()
return answer