2.9. Functions

Functions are an indispensable part of programming in that they wrap code into blocks that can be executed only when needed. They also allow code blocks to be reused and edited efficiently, without having to copy, paste, and edit repeatedly. Without functions, all code would be executed in a linear progression from start to finish, and edits would require changes to every single occurrence of any repeated code. We’ll look at functions in three parts: minimal structure, use of arguments, and returning values. Figure 2-3 identifies examples of each of the parts of a function that we’ll discuss.