Learning to Program in C++

Setting the Standard

We have seen how a polymorphic object works once it is set up, so let's continue our examination of the StockItem class by looking at the "standard" member functions; that is, the ones that are necessary to make it a concrete data type. As you may remember, these are the default constructor, the copy constructor, the assignment operator (operator =), and the destructor.

It may occur to you to wonder why we have to rewrite all these functions; what's wrong with the ones we've already written for StockItem? The answer is that these functions create, copy, and destroy objects of a given class. Now that we have changed the way we want to use the StockItem class and the way it works, we have to rewrite these functions to do the ...