Overview

Functions are a fantastic way of bundling a series of statements together conceptually to make your code much clearer. You’ve already been using them a lot, but now you’ll learn how to make your own and how to think through what they are doing.

Basic Learning Objectives

Before the start of class, you should be able to:

  • Define the terms function and parameter
  • Predict the return value of a function given sample parameter values (aka arguments)
  • Define and use a new function to accomplish a simple task

Advanced Learning Objectives

During and after class, you should be able to:

  • Explain the difference between a return value and a side effect
  • Explain when the code in a function is executed
  • Explain what the scope of a function is and how it impacts variables used inside the function
  • Define and use a new function with multiple parameters to accomplish a task
  • Identify when a function should be created

Readings

You should read the following (note there are a few places where an old checkpoint doesn’t show correctly, don’t worry about it):

Checks

Submit answers to the following on Moodle:

  • What output will the following code produce (Checkpoint 4.4.6): 
      CONSTANT_VALUE = -8
  def cyu(n1: int, n2: int) -> int:
      print(n1 + n2 - CONSTANT_VALUE)

  cyu(4, 3)
  • Write a function cheer_up that takes a string and returns it with a :) at the end.