12. Adding and Deleteing from a queue

A queue maintains two pointers

1. A 'front of queue' pointer.
2. An 'end of queue' pointer.

These are used to add and remove nodes from the queue

To add an item to a queue.

1. Is the queue full?
2. Case 1: Queue is full
   1. Return an error message to the calling function
   2. End of task
3. Case 1: Queue is not full
   1. Allocate memory to the new node
   2. Adjust the rear pointer to locate the new node

To remove an item to a queue.

1. Is the queue empty?
2. Case 1: Queue is empty
   1. Return an error message to the calling function
   2. End of task
3. Case 1: Queue is not empty
   1. Mark the memory the node used as free once more
   2. Adjust the rear pointer to locate the previous node
   3. End of task