Queue and Stack behavior in C Sharp (C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the main difference between a Queue and a Stack?

A Queue follows First-In-First-Out (FIFO) order, meaning the first item added is the first removed. A Stack follows Last-In-First-Out (LIFO) order, meaning the last item added is the first removed.

beginner

In C#, which method adds an item to a Queue?

The Enqueue() method adds an item to the end of the Queue.

beginner

How do you remove the top item from a Stack in C#?

Use the Pop() method to remove and return the item at the top of the Stack.

intermediate

What happens if you call Dequeue() on an empty Queue in C#?

It throws an InvalidOperationException because there are no items to remove.

intermediate

Explain the behavior of Peek() method in both Queue and Stack.

The Peek() method returns the next item to be removed without removing it. For a Queue, it returns the item at the front. For a Stack, it returns the item at the top.

Which method adds an element to the top of a Stack in C#?

A Pop()

B Enqueue()

C Push()

D Dequeue()

The Push() method adds an element to the top of the Stack.

What order does a Queue follow?

A First-In-First-Out (FIFO)

B Last-In-First-Out (LIFO)

C Random order

D Sorted order

A Queue follows First-In-First-Out (FIFO) order.

What does the Pop() method do in a Stack?

A Removes and returns the top item

B Returns the bottom item without removing

C Adds an item to the bottom

D Removes the first item added

Pop() removes and returns the top item of the Stack.

Which method removes the front item from a Queue?

A Pop()

B Push()

C Peek()

D Dequeue()

Dequeue() removes and returns the front item of the Queue.

What will happen if you call Peek() on an empty Stack?

A Returns null

B Throws InvalidOperationException

C Returns default value

D Removes an item

Calling Peek() on an empty Stack throws InvalidOperationException.

Describe how Queue and Stack differ in the order they remove items.

Think about a line of people versus a stack of plates.

Explain the purpose of the Enqueue, Dequeue, Push, and Pop methods in C# collections.

Match methods to adding or removing items in Queue or Stack.