Conditionals Preparation

Overview

Frequently you want a program to do one thing in one situation and a different thing some other time. The programming structure that allows for this is a conditional. Today will be focused on the conditional structures in Python and the necessary Boolean values.

Basic Learning Objectives

Before class, you should be able to:

• Define what Boolean values are
• Recognize the if/elif/else syntax for conditionals
• Define what the and, or, and not logical operators do
• Define what the in operator does in the basic case

Advanced Learning Objectives

After class, you should be able to:

• Use basic, nested, and chained conditionals to solve a problem
• Use logical operators to solve a problem
• Predict what code will do when short-circuit boolean evaluation is used

Resources

You should read/watch the following:

• 5.1 What we can do with Conditionals
• 5.2 Boolean Values and Expressions
• 5.3 Logical operators
• 5.4 The in and not in opreators
• 5.6 Conditional Execution
• 5.7 Omiting the else Clause
• 5.8 Nested conditionals
• 5.9 Chained conditionals

Checks

Submit answers to the following on Moodle.

• (Checkpoint 5.9.2) What will the following code print?

x = 3
y = 5
z = 2

if x < y and x < z:
  print("a")
elif y < x and y < z:
  print("b")
else:
  print("c")

• Write a snippet of code that prints out whether the value in the variable mystery is greater than or less than 5.