Write a C++ program to implement circular queue ADT using an array. Java Program To Implement Queue Adt Using Array. Java Program To Implement. Queue ADT; Queue Using Array; Queue Using. One dimensional array. But, queue implemented using array can store only. Program to implement Queue using Array.

The queue is one of the most widely used data structures. So what are queues? Where are they used? How are they implemented? The Basics A queue is a FIFO sequence. Addition takes place only at the tail, and removal takes place only at the head. The basic operations are: • enqueue(x): add an item at the tail • dequeue: remove the item at the head • peek: return the item at the head (without removing it) • size: return the number of items in the queue • isEmpty: return whether the queue has no items Usage You tend to see queues often.

Exercise: Draw a series of pictures that trace the execution of the following code fragment: Queue q = new BoundedQueue(4); q.enqueue('A'); q.enqueue('B'); q.enqueue('C'); q.dequeue(); q.enqueue('D'); q.dequeue(); q.enqueue('E'); q.enqueue('F'); A Linked Implementation This particular version uses dual head and tail pointers. Note here: • Adding to an empty queue is a little different than adding to a queue that already has elements, because we have to update the head in the former case but not the latter. • Removal has three distinct cases: removing from a queue with more than one element, removing the last element, and removing from an empty queue. Exercise: Draw a class diagram for the interface and three implementing classes above. Unit Testing Here is what we need to test: • A queue is empty on construction • A queue has size 0 on construction • After n enqueues to an empty queue, n >0, the queue is not empty and its size is n • If one enqueues x then dequeues, the value dequeued is x. • If one enqueues x then peeks, the value returned is x, but the size stays the same • If the size is n, then after n dequeues, the stack is empty and has a size 0 • If one enqueues the values 1 through 50, in order, into an empty queue, then if 50 dequeues are done the values dequeues are 1 through 50. • Dequeueing from an empty queue does throw a NoSuchElementException • Peeking into an empty queue does throw a NoSuchElementException • For bounded queues only, pushing onto a full stack does throw an IllegalStateException We really have three classes to test, but the test cases share a bunch of things in common; the common tests can go in a base class.

Note how the base test class tests any kind of queue.

It's cheating, but: if you are going to be looking at circular queues, you should really review the implementation of. Reviewing this implementation: There's no particularly good reason to restrict it to ints, is there? CircularQueue isn't much more work.

It's likely a cleaner design to treat the Queue as being backed by an infinite array, rather than wrapping your pointers over and over again. So front and rear should tell you which item in the queue history that they point at, and reserve the modulus function for accessing the array itself. This gives you some nice invariants to check, like rear >= front.

I definitely get tangled by the variable names. InsertCursor and retrieveCursor might be clearer.

Or writeTo and readFrom. Why aren't you implementing java.util.Queue? (Answered by rolfl - because that interface brings too much baggage along with it. It might still be a good idea to support offer(E), though.) Throwing new exceptions each time you hit a problem condition can get expensive. Java.util.Queue.add() does it, so I suppose you've got some prior art in your defense, but if you aren't going to implement that interface, then perhaps you can more cleanly support congestion control. Because every method is synchronized here, lock contention may get to be a problem when you start using this from multiple threads. There doesn't seem to be a need for currentSize, since you can always compute it from front and back.

Do you really intend to expose these member variables to other classes in your package? They should probably be private. And the array should likely be final as well.

A queue data structure can be implemented using one dimensional array. But, queue implemented using array can store only fixed number of data values. The implementation of queue data structure using array is very simple, just define a one dimensional array of specific size and insert or delete the values into that array by using FIFO (First In First Out) principle with the help of variables 'front' and ' rear'. Initially both ' front' and ' rear' are set to -1.

Whenever, we want to insert a new value into the queue, increment ' rear' value by one and then insert at that position. Whenever we want to delete a value from the queue, then increment 'front' value by one and then display the value at ' front' position as deleted element. Queue Operations using Array Queue data structure using array can be implemented as follows.

Airbag Software Reset more. Before we implement actual operations, first follow the below steps to create an empty queue. • Step 1: Include all the header files which are used in the program and define a constant 'SIZE' with specific value. • Step 2: Declare all the user defined functions which are used in queue implementation. • Step 3: Create a one dimensional array with above defined SIZE ( int queue[SIZE]) • Step 4: Define two integer variables 'front' and ' rear' and initialize both with '-1'. ( int front = -1, rear = -1) • Step 5: Then implement main method by displaying menu of operations list and make suitable function calls to perform operation selected by the user on queue.

EnQueue(value) - Inserting value into the queue In a queue data structure, enQueue() is a function used to insert a new element into the queue. In a queue, the new element is always inserted at rear position. The enQueue() function takes one integer value as parameter and inserts that value into the queue.

We can use the following steps to insert an element into the queue. • Step 1: Check whether queue is FULL. ( rear == SIZE-1) • Step 2: If it is FULL, then display 'Queue is FULL!!! Insertion is not possible!!!' And terminate the function.

• Step 3: If it is NOT FULL, then increment rear value by one ( rear++) and set queue[rear] = value. DeQueue() - Deleting a value from the Queue In a queue data structure, deQueue() is a function used to delete an element from the queue. In a queue, the element is always deleted from front position. The deQueue() function does not take any value as parameter. We can use the following steps to delete an element from the queue. • Step 1: Check whether queue is EMPTY. ( front == rear) • Step 2: If it is EMPTY, then display 'Queue is EMPTY!!!

Deletion is not possible!!!' And terminate the function. • Step 3: If it is NOT EMPTY, then increment the front value by one ( front ++). Then display queue[front] as deleted element. Then check whether both front and rear are equal ( front == rear), if it TRUE, then set both front and rear to ' -1' ( front = rear = -1). Display() - Displays the elements of a Queue We can use the following steps to display the elements of a queue. • Step 1: Check whether queue is EMPTY.

( front == rear) • Step 2: If it is EMPTY, then display 'Queue is EMPTY!!!' And terminate the function. • Step 3: If it is NOT EMPTY, then define an integer variable ' i' and set ' i = front+1'. • Step 3: Display ' queue[i]' value and increment ' i' value by one ( i++). Repeat the same until ' i' value is equal to rear ( i.