A queue is a data structure where items are added at the rear and removed from the front, following a first in first out (FIFO) principle. Key operations include creating an empty queue, getting the front element, enqueuing new elements, dequeuing elements, and checking if the queue is empty. An example of a queue is a line of customers at a bank.

1. Queues

2. Queues
“A Queue is a special kind of list, where items
are inserted at one end (the rear) And
deleted at the other end (the front)”
Other Name:
 First In First Out (FIFO)

3. 3
A
B
A
C
B
A
D
C
B
A
D
C
B
rear
front
rear
front
rear
front
rear
front
rear
front
First In First Out
Difference from Stack:
Insertion go at the end of the list, rather than
the beginning of the list.

4. Common Operations on Queues
(Queue ADT)
1. MAKENULL(Q): Makes Queue Q be an empty list.
2. FRONT(Q): Returns the first element on Queue Q.
3. ENQUEUE(x,Q): Inserts element x at the end of Queue Q.
4. DEQUEUE(Q): Deletes the first element of Q.
5. EMPTY(Q): Returns true if and only if Q is an empty queue.
Example:
Line of customers in a bank