Queues

Another ADT is the queue. The queue is the opposite of a stack in that it is known as first in and first out data structure. All data insertions in a queue come in at one end of the list and all the deletions will come at the other end of the list. It can be thought of like the line at the supermarket. A person enters at one end is exits at the other end. There are several ways to implement a queue . The first is a pointer based implementation. The pointer based implementation is essential the same as a linked list with two extra pointers to track the first and last data elements in the queue. The second implementation is done through and array. The array is implemented by setting the max size and when it is completely filled the array dumps the data that was in the last element of the array and shifts all the other elements down to the next element. One of the common uses of queues are when a certain resource is needed by more than one part of the computer. This can commonly be found in the use of a printer since only one item can be printed at a time queues are often used to delegate the sequence of documents printed.