Data structures/queue using array2.cpp

[ehtashammd07]

update a queue

fixes #2690

Issues in your code:
Deque() causes incorrect shifting

The shifting logic in Deque() is incorrect.
Instead of shifting all elements and updating rear, use front to track the front element.
Incorrect Underflow condition

If front == rear, the queue is empty, but you still proceed with shifting.
Hardcoded queue size (10)

You are not handling a circular queue approach, which is more efficient for queues.
Loop exits incorrectly in main()

The loop should have an explicit exit condition (0 isn't handled)

[ehtashammd07]

final update