The abstract data type approach to programming in C, as you've seen, involves the following three steps:
Describing a type, including its operations, in an abstract, general fashion
Devising a function interface to represent the new type
Writing detailed code to implement the interface
You've seen this approach applied to a simple list. Now, apply it to something slightly more complex: the queue.
A queue is a list with two special properties. First, new items can be added only to the end of the list. In this respect, the queue is like the simple list. Second, items can be removed from the list only at the beginning. You can visualize a queue as a line of people buying ...