→ Well, Step 2 is mainly deallocating any memory assigned to the element being dequeued. ★ But we just implemented Step 1, right? Where's Step 2? The queue can be empty when the dequeue operation is called. ▹ Can you think of an exception in this case like the one above of the queue is full? In the end, return the value stored at the Otherwise, increase the value of front by 1 i.e. So we need to set the empty queue condition before returning the value i.e. After the deletion of this single element, queue become empty. , then this is a case of a single element in the queue. Which end of the queue do we use to delete an element? The front end! How do we delete an element?Īccess the element which is stored in front position i.e. Now that we have discussed the insertion of an element, let’s discuss the deletion of an element. ▹ What if the queue is filled up to its capacity? We shall check if the queue if full before inserting a new element and throw an error if it is. Simple, right? Any exceptions that come to mind? In a circular array, the index after the last element is that of the first element. So much that its declaration is not even slightly different. ![]() Don't stress, its quite similar to our normal array. To implement a circular queue, we would need a circular array. In order to improve our memory utilization, we will implement what's known as a ★ You are also required to allocate memory toĪccording to the conventions of the language you use to implement it. Let us also create a constructor which initializes Let us wrap this group of data members in a The size of a queue should not exceed this limit Here, 8 is a pre-defined capacity of the queue. Will hold index positions of front end and back end respectively. Instead of using actual pointers, we will use indexes, So first, after initializing an array, we need two pointers, one each to point to the front end and back end. Only the first and last elements are accessible in a queue. But what are the access criteria in a queue? Can you access any element of the queue? We shall be implementing queue in two different ways by changing the underlying container:Īn array is one of the simplest containers offering random access to users based on indexes. You should remember one very important thing though → This is as simple as its concept because we just need to simply keep in mind all of its properties and operations. The key idea of queue implementation is to use both ends of the queue: front end for deleting elements and back/rear end for inserting elements. isEmpty() conventionally returns a boolean value: True if size is 0, else False. To prevent performing operations on an empty queue, the programmer is required to internally maintain the size of the queue which will be updated during enqueue and deque operations accordingly. This is similar to the peek operation in stacks, it returns the value of the element at the front without removing it. Naturally, the element inserted first will be at the front of the queue so we will remove theĮlement and let the element behind it be the new front element. Since queue follows the FIFO principle we need to remove the element of the queue which was inserted at first. Similarly, a new element in a queue is inserted at the back of the queue.ĭequeue means removing an element from the queue. ![]() In a normal queue at a ticket counter, where does a new person go and stand to become a part of the queue? The person goes and stands in the Enqueue means inserting an element in the queue.
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