SIMPLE QUEUE

• Array representation of the queue two pointer variable such as front and rear, which indicates the position of elements present in the queue of the front and rear ends.
• Array representation of the queue which involves the declaration of one_dimensional array.

                                           

• simple queue operations are:                                 

        (1)Insert an element at the rear end.

        (2)Delete an element at the front end.

        (3)Display the element of the queue.

Insert an element at the rear end: 

   Algorithm: Insert_rear(item)

    STEP 1: Check for queue overflow

                     if(rear==Queue_size-1)

                     {

                       print("QUEUE OVERFLOW");

                       return;

                      }

     STEP 2: Increment rear pointer.

                        rear=rear+1;

     STEP 3: Insert element.

                        queue[rear]=item;

     STEP 4: Stop algorithm.

                         return;

EXAMPLE:

• Maximum queue size is 5.Assume 4 elements are inserted.

• The queue can insert at most 5 elements & any new elements should be inserted at rear end .it has inserted to the right of the element 40  (ie) queue queue[4] then increment rear pointer    by 1. 

• Now the rear pointer reaches "Queue_size-1" position so we cannot insert new elements into queue.

Delete an element at the front end:

     Algorithm: delete_front()

     STEP 1:Check for underflow.

                     if(front>rear)

                     {

                       Printf("Queue is underflow");

                       return;

                      }

     STEP 2:Delete element.

                       queue[rear];

     STEP 3:Decrease the front pointer.

                        front=front+1;

     STEP 4:Stop algorithm.

                         return;

EXAMPLE:

• After deleting element 10 from the queue the pointer variable front should be incremented by 1 then front pointer points to the element 20.

Display the elements of the queue:

           The elements of the queue can be displayed only if the queue is not empty.

  

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