1. 5. Loops Let's Learn Python and Pygame
Aj. Andrew Davison, CoE, PSU Hat Yai Campus
5. Loops
Make a program do things over-and-over-and over again.
Counting loops; Conditional loops.
Games: guessing, ghost, hangman.

2. 1. Counting Loop
Loop1.py

3. Using the Counting Loop Variable
Loop2.py
The [ … ] is
called a list.
More later

4. Using the Counting Loop Var.
Loop3.py

5. Counting without Numbers
Coolest.py
A list can contain anything,
not just numbers

6. Counting Loop Using a Range
Loop4.py
Counting Loop Using a Range
Less typing,
but it goes
from 1 to 4

7. Eight Times Table
EightTimes.py
This range
goes from
1 to 10

8. Range with a Step Amount
BlastOff.py
This range
goes from
10 to 1 in a
step of -1
This program
took 10 secs
to run.

9. 2. Drawing a Turtle Square
from turtle import Turtle t = Turtle() t.forward(100) t.right(90)
This is Square.py from the
Modules slides.
The forward() and right() code
is repeated four times.
A loop will make this code
smaller, and easier to change.

10. Square.py with a Loop

11. Square1.py with Variables
The variables make it easy to change the code.
What if numSides == 3 and angle = 120?

12. Shape.py

13. Connect No. Sides and Angle
For a square, numSides == 4, angle == 90
For a triangle, numSides == 3, angle == 120
The math connection:
numSides * angle == 360
Test it. A 5-sided shape (pentagon) means:
5 * angle == 360
so angle = 360/5

14. Revised Shape.py

15. Make Shape Code Easier to Use
In ShapeInput.py
read in the numSides data using the turtle command numinput()
calculate the angle using the numSides data

16. ShapeInput.py

18. A Square Spiral
SquareSpiral1.py

19. SquareSpiral3.py
Square (90  91) + Color
no need to write

20. Square  Circle

21. ColorSquareSpiral.py
Square Spiral Again
with different colors

22. 3. Conditional Loops
A conditional loop uses a test to decide when to stop looping
the same kind of test as in "if"

23. Eight Times Table Again
WhileLess.py
i < 11
is the test
the while body
is run over
and over
most while body's
need to include
an increment

24. Flowchart for Conditional Loop
program execution
i = 1
no; so finish
i < 11?
yes; keep going
loop back.
action
i = i + 1
execution
continues...

25. Eight Times Table Problem
WhileProb.py
Eight Times Table Problem
I typed
ctrl-c
i never changes because
there is no increment. This
means i never reaches 11
and so the loop never ends.

26. While that Likes "3"
While3.py

27. Using break in a Loop
Breaker.py
break
makes
Python
leave the
loop

28. 4. A Number Guessing Game
GuessingGame.py

31. Uses two modules;
a while loop;
if tests