1. Nate Brunelle Today: Repetition, A Trip To The Moon
CS1110
Nate Brunelle
Today: Repetition,
A Trip To The Moon

2. Questions?

3. Last Times
exam
review
If, elif, else

4. Repetition (pseudocode)
def wash_hair(): Repeat 3 times: Lather() Rinse def Lather(): put shampoo in hand Repeat until hair is foamy: rub hand through hair

5. Repetition (Python), aka loops
def wash_hair(): for i in range(3): Lather() Rinse def Lather(): put shampoo in hand while not hair_is_foamy: rub hand through hair

6. “While” Loops while loop while boolean expression:
Keep repeating until the boolean expression is False
“so long as this is True, keep doing the action”
while boolean expression:
action1
action2

7. Conditional decision Statement
if boolean expression:
action
elif boolean expression:
another action
else:
yet another action
0 or more
0 or 1

8. Lists My_list[i] # gives the ith thing in the list (starts with 0)
A way of collecting together a bunch of things, and giving it all one name
[the things separated by commas]
my_list = [1, 2, 3, 4]
my_list = [“one”, “two”, “three”, “four”]
my_list = [1, “two”, 3, “four”]
len(my_list) # gives the number of things in the list, in this case 4
My_list[i] # gives the ith thing in the list (starts with 0)
my_list[1] -> “two”

9. “for” Loops For loop for [variable v] in [collection]: action
Do the action a certain number of times
“do the action once per each thing in here”
The variable takes the value of each thing in the collection in order
for [variable v] in [collection]:
action
for i in range(5):
print(‘hi’)
Range(5) -> [0,1,2,3,4]