Implementation of Queues

Linked Implementation of Queues
The items are deleted from the front of a queue and inserted at the rear. A pointer to the first element of a list represent the front of the queue. Another pointer to the last element of the list represent the rear of the queue. If (empty(q))
{
Printf(“Queue underflow”);
Exit(1);
}
P=q.front;
X=info(p);
q.front=next(p) ;
if(q.front == null)
q.rear = null;
freenode(p);
return(x);
The operation insert(q,x) is implemented by
P = getnode();
Info(p) = x;
Next(p) = null;
If (q.rear == null)
q.front = p;
else
next(q.rear) = p;
q.rear = p;