1. Types, Truth, and Expressions (Part 2)
Intro to Computer Science
CS1510
Dr. Sarah Diesburg

2. Observations from PA 1
Variable names matter (don’t call it startingMileageStr when it contains a number)
Import math?
Why would you say float(2.2)
Do your own work!

3. Review : Python if Statement
if <expression> :
suite
Evaluate the expression to a Boolean value (True or False)
if True, execute all statements in the suite

4. Review : Warning About Indentation
Elements of the “suite” must all be indented the same number of spaces/tabs
Python only recognizes suites when they are indented the same “distance”
You must be careful to get the indentation right to get suites right.

5. Let’s test your knowledge
Look at #1-4 in my questions.py program…
Which letters are printed? A B
A and B
Neither

6. Python Selection The process is: evaluate the boolean
if boolean expression: suite1 else: suite2
The process is:
evaluate the boolean
if True, run suite1
if False, run suite2

7. Let’s test your knowledge
Let’s look at statements with if, elif, else
Problems #5-9 : Which letters are printed? A B
A and B
Neither

8. Python Selection The process is: evaluate expression1
if boolean expression1: suite1 elif expression2: suite2
The process is:
evaluate expression1
if True, run suite1
If False, evaluate expression 2
if True, run suite2

9. Python Selection – All Together
if boolean expression1: suite1 elif boolean expression2: suite2 #(as many elif’s as you want) else: suiteLast

10. if, elif, else, the Process
Evaluate boolean expressions until:
The boolean expression returns True
None of the boolean expressions return True
If a boolean returns True, run the corresponding suite. Skip the rest of the if
If no boolean returns True, run the else suite, the default suite