SLIDE 1
Loops Loops Loops!
How can we repeat a piece of code without having to write it out over and
- ver?!
LOOPS Loops Loops Loops! How can we repeat a piece of code without - - PowerPoint PPT Presentation
LOOPS Loops Loops Loops! How can we repeat a piece of code without - - PowerPoint PPT Presentation
Session 6 LOOPS Loops Loops Loops! How can we repeat a piece of code without having to write it out over and over?! With loops! The Game Loop For Loop vs. While Loop For Loops While Loops Start/End are Known Start/End not Always Clear
SLIDE 2
SLIDE 3
The Game Loop
SLIDE 4
For Loop vs. While Loop
For Loops While Loops Start/End are Known Start/End not Always Clear Range “Until” something happens
SLIDE 5
For Loops
for i in range(5): print(“I will not chew gum in class.”)
- What do you think this will print?
- C/P the first example of loops.pdf into a new
PyCharm file (loops.py) and find out!
SLIDE 6
Solution
Output: I will not chew gum in class. I will not chew gum in class. I will not chew gum in class. I will not chew gum in class. I will not chew gum in class.
SLIDE 7
Example 2
for i in range(5): print("Please,") print("Can I go to the mall?")
- What will this print?
- Predict and test!
SLIDE 8
Solution
Please, Please, Please, Please, Please, Can I go to the mall?
SLIDE 9
Example 3
for i in range(5): print("Please,") print("Can I go to the mall?")
- How about this one?
- Think first, run second!
SLIDE 10
Solution
Please, Can I go to the mall? Please, Can I go to the mall? Please, Can I go to the mall? Please, Can I go to the mall? Please, Can I go to the mall?
SLIDE 11
Loopy Stuff
For i in range(10) print(i)
- What number does this loop stop on?
- (this is a trick question)
SLIDE 12
Solution
1 2 3 4 5 6 7 8 9
SLIDE 13
Workarounds
#Print the numbers 1 to 10, version 2 for i in range(10): print(i+1) #Print the numbers version 2 for i in range(1,11): print(i)
SLIDE 14
Nested Loops
# What does this print? Why? for i in range(3): print("a") for j in range(3): print("b")
- What will this print?
SLIDE 15
Nested Loops
# What does this print? Why? for i in range(3): print("a") for j in range(3): print("b") print("Done")
SLIDE 16
Counter Variables, pt. 2
total = 0 for i in range(5): new_number = int(input("Enter a number: " )) total += new_number print("The total is: ", total)
SLIDE 17
Example
# What is the value of sum? sum = 0 for i in range(1, 101): sum = sum + i print(sum)
SLIDE 18
Extra Loops Practice
# What is the value of a? a = 0 for i in range(10): a = a + 1 print(a)
SLIDE 19
Extra Loops Practice
# What is the value of a? a = 0 for i in range(10): a = a + 1 for j in range(10): a = a + 1 print(a)
SLIDE 20
Extra Loops Practice
# What is the value of a? a = 0 for i in range(10): a = a + 1 for j in range(10): a = a + 1 print(a)
SLIDE 21
While Loops
i = 0 while i < 10: print(i) i = i + 1 for i in range(10): print(i)
SLIDE 22
CAUTION
while range(10): print(i) Don’t use range with a while loop! The range function only works with the for
- loop. Do not use it with the while loop!
SLIDE 23
Counter Variables, pt. 3
i = i + 1 → i += 1 i = 0 while i < 10: print(i) i += 1 i = 1 while i <= 2 ** 32: print(i) i *= 2 What does this print?
SLIDE 24
Loop Until Quit
done = False while not done: quit = input("Do you want to quit? ") if quit == "y": done = True attack = input("Does your elf attack the dragon? ") if attack == "y": print("Bad choice, you died.") done = True
SLIDE 25
Solution
done = False while not done: quit = input("Do you want to quit? ") if quit == "y": done = True elif quit =="n": attack = input("Does your elf attack the dragon? ") if attack == "y": print("Bad choice, you died.") done = True
SLIDE 26
Strength-o-Meter
- Make a new activity file,
strength_o_meter.py, in Session 6
- Build a while loop to report and increase
player strength
- Get crazy(should I say loopy?) with it!