4.2.3 - FoDS (Stacks)

Question 1

What are pointers

Answer 1

References to the location of stored data items in stack and queues

Question 2

What type of data structures are stacks, and what does the term used to describe it mean

Answer 2

LIFO - Last in first out
meaning that the last item placed in is the first item taken out

Question 3

How many pointers do stacks have and where do they point

Answer 3

• 1 which points to the front of the stack

Question 4

What are the 4 key functions of stacks

Answer 4

• Push/Add items
• Pop/Remove items
• Peek/Top which returns the value of the top element without removing it
• Testing whether full or empty

Question 5

How does the stack pop work

Answer 5

• Check to see that the stack isn’t empty
• If empty report an error and stop
• Copy data item in the location pointed to by stack pointer
• Decrement the stack pointer

Question 6

How does the push function work

Answer 6

• Check to see that the stack is not full
• If full report an error and stop
• Otherwise, increment the pointer
• Insert new data into the location pointed to by the pointer

Question 7

What is a peek/top

Answer 7

• A function of a tack that returns the value of the top element without removing it