C++

23.3    A Class as a Function

So far, you can do two things with a function: you can define it, and you can call it. It becomes exciting and truly flexible only when you consider functions not just as a piece of outsourced program code but as objects like all other C++ objects. When you pass a function as a parameter, receive it as a return value, or simply store it in a variable for later use, you are using functions as objects.

I'll start with a very simple example. Say you want to write something that performs either an addition or a multiplication operation depending on a parameter. In the context of this chapter, I would like to call the thing that sometimes performs one operation and sometimes another a procedure to conceptually distinguish ...