How Do I Work with Program Functions to Edit Data and Trigger Actions?

Functions are the workhorse of most programming languages to do the actual job, whether it’s taking data from the user, reading from or writing to files and databases, manipulating data, displaying information, controlling the behavior of user interfaces, and much more. This chapter is about how functions work, how to call them from within your program, how to extend the capabilities of your programming language by finding suitable function libraries/modules on the internet to help you solve your tasks, and finally how to write your own functions to make parts of your code reusable.