1. Nate Brunelle Today: Conditional Decision Statements
CS1110
Nate Brunelle
Today: Conditional Decision Statements

2. Questions?

3. Last Time
If, elif, else

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

5. Values and Types (not exhaustive)
Operators
-50 ,0 ,5, 30, 512
int
3+7, 3*7,
3-7, 3/7
0.5, 1.2,
float
+, *, -, /, //, %, **, compare
‘hi’, “hi”, ‘hello world! ✃’
str
+, * int
Print, input
function
print()
True, False
bool
and, or, not

6. and, or, not examples x<2 and x>0 x<0 or x>2 not x>2
When all things are true
X=1
x<0 or x>2
When any of the things are true
X=-1
X=15
X=2
X=0
not x>2
When the thing is false

7. and, or, not and or not True if all things are True
False if any things are False or
True if any things are True
False if all things are False
not
True if the thing was False
False if the thing was True

8. Leap year rules Year is divisible by 4 Unless divisible by 100
div400 or (div4 and not div100)

9. “Truthiness” of all things in python
“Truish” Things
“Falsish” things
True
False
“True”
1, -1
0.0
None
“ “
Empty things
“False” ‘’ “”
Advice: make sure every and, or has a bool on both sides

10. What do and, or evaluate to?
Evaluate to the first truish thing
If all things are falsish, give the last falsish thing
And
Give the first falsish thing
If all things are truish, give the last truish thing

11. Chained Comparitors 1 < 2 < 3 1 < 2 and 2 < 3
True
1 < 2 < 3
1 < 2 and 2 < 3
1 < 2 > 0 < 8 > -5 == -5
Gives true
True