Checking Inventory for a Misplaced Item

By this point, you very understandably might have gotten the notion that we have to make changes to our classes every time we need to do anything slightly different in our application program. In that case, where's the advantage of using classes instead of just writing the whole program in terms of shorts, chars, and so on?

Well, this is your lucky day. It just so happens that the next (and last) scenario we are going to examine requires no more member functions at all; in fact, we don't even have to change the application program. Here it is, for reference: "Judy comes in looking for chunky chicken soup; there's none on the shelf where it should be, so we have to check the inventory to see if we're supposed to have any".

The reason we don't have to do anything special for this scenario is that we're already displaying the name and inventory for the item as soon as we find it. Of course, if we hadn't already handled this issue, there are many other ways that we could solve this same problem. For example, we could use the Display member function of StockItem to display an item as soon as the UPC lookup succeeds, rather than waiting for the user to indicate what operation our application is supposed to perform.

For that matter, we'd have to consider a number of other factors in writing a real application program, even one that does such a simple task as this one. For example, what would happen if the user indicated that 200 units of a particular item had been sold when only 100 were in stock? Also, how would we find an item if the UPC isn't available? The item might very well be in inventory somewhere, but the current implementation of Inventory doesn't allow for the possibility of looking up an item by information other than the UPC.

Although these topics and many others are essential to the work of a professional programmer, they would take us too far afield from our purpose here. We'll get into some similar issues later, when we discuss the topic of "software engineering" in Chapter 12.

Now let's review what we've covered in this chapter.