In chapter 3, you’ll learn the most important things to know about functions and subroutines (collectively called procedures). They’ll allow you to abstract away any piece of code that you need to run many times. Functions and subroutines are fundamental building blocks that will allow you to write reusable, composable, and complex (but not complicated) code. You’ll apply this knowledge to refactor the tsunami simulator we started in chapter 2.
In chapter 4, you’ll learn about modules and how to use them to organize your data and procedures in reusable and portable components.
Chapter 5 covers arrays, the fundamental Fortran data structure. You’ll learn how to declare, initialize, and use arrays, as well as how to leverage whole-array arithmetic to greatly simplify your code. You’ll use arrays for the analysis of stock price time series.
Finally, chapter 6 covers I/O. You’ll learn how to read and write data from the standard input, output, and error streams, as well as how to read from and write to files on disk. You’ll also learn how to format numerical data as text. You’ll practice these skills by writing a minimal note-taking app for the command line.