Circular Queues- Insertion of item into circular queue

Procedure EnCqueue (Q, data)

This procedure inserts value data in circular queue.

Step 1 If Empty

if (CQ (front = – 1) then

{

set CQ (front) ¬ 0

set CQ (rear) ¬ 0

}

elseif (CQ (rear) = (SIZE – 1) then

set CQ (rear) = 0

else

set CQ(rear) ¬ CQ(rear) + 1

Step 2 Inserts value at rear end

set CQ (item [CQ (rear)]) ¬ data

Step 3 return at the point of call

return

Equivalent C code is given below:

void EnCqueue (queue * CQ, int data)

{

if (CQ ® front = = – 1

Q ® front = CQ ® rear = 0;

else if (CQ ® rear = = SIZE – 1

CQ ® rear = 0;

else

CQ ® rear = CQ ® rear + 1; ...(i)

CQ ® item [CQ ® rear] = data;

}