Until now, we have been looking at how to create certain types and how to use variables as a tool for representing values in our programs. These are all fundamental concepts to understand when learning how to program, and this chapter will build upon that. In this chapter, we will take a look at something called functions.

As you have learned from Chapter 4, Favorite Things, a variable can represent a value in our program. This means that without knowing the actual value, we can use the variable throughout our program to represent that value. In a way, you could say that we are reusing the value throughout the program by just using our variable. A function shares similar advantages in the sense that we are also reusing code when we use a function. We say that a function abstracts an amount of work we only have to define once. This idea of reusing code is central to programming and functions are just a tool to help programmers do that.

In this chapter, the reader will...