Logical Operators

Jake Shoudy

August 22, 2022

CSCI 110 - Lecture 6

Today’s Agenda

Announcements

Pre-class Surveys

Two surveys posted on Ed

Please take them 🙏 🙏 🙏

Google TechExchange

What: Google program for HBCU students to learn CS things on Google campus (targeted at sophomores)

Google program leads will be on Fisk Campus to talk about it!

Timing: Aug 29th 2022, 5-7pm See more here

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Reminder: HW1

Due Wednesday at 11:59pm

Only your most recent submission will be graded. If you submit after the deadline a late day will be used.

Project 1: Part 1

• Blackjack!
• 3 files:
• Name: take a card # and output the card name
• Value: take a card # and output the card value
• End Status: take a hand value and output BLACKJACK or BUST
• Released in Ed
• Due on Sunday at 11:59pm

Quiz 1 Scores

Quiz 1 Notes

• Don’t forget to submit each question! You can always change the answer and resubmit.
• Make sure you are logged in to YOUR account
• BE ON TIME! From now on quizzes will start EXACTLY at :05 and end at :20
• Reminder we drop your lowest 2 scores at the end of the semester and in total they are only 5% of your grade
• Quiz 2 is this Friday!
• If you score higher than you did on quiz 1, we will replace your quiz 1 score.

TA Office Hours

• Aminu
• Monday’s from 5-6pm
• Library 3rd floor
• Aman
• Monday’s from 10:30-11:30am
• Library 3rd floor
• Angel/Arun
• Will be added soon
• All available on class calendar

Recap

Review: I / O

What is it?

User providing input and receiving output

Why is this important?

Many programs and apps need user input, and based on input, program provides output

How (in Python)?

input(): get input from user

print(): show output to user

Review: I/O

age = input(“how old are you today? ”)

print(“Next year you will be “ + (age + 1) + “ years old”)

Traceback (most recent call last):

File "main.py", line 2, in <module>

print('Next year you will be ' + (age + 1) + ' years old')

TypeError: can only concatenate str (not "int") to str

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Review: I/O

age = int(input(“how old are you today? ”))

print(“Next year you will be “ + str(age + 1) + “ years old”)

Review: Conditionals & I/O

fruit = int(input())

if fruit / 2 >= 2:

if fruit % 2 == 1:

print('apples')

elif fruit % 3 == 2:

print('apples')

else:

print('oranges')

else:

print('oranges')

Review: Conditionals & I/O

fruit = int(input())

if fruit / 2 >= 2:

if fruit % 2 == 1:

print('apples')

elif fruit % 3 == 2:

print('apples')

else:

print('oranges')

else:

print('oranges')

4

6

3

5

8

oranges

oranges

oranges

apples

apples

Review: Conditionals & I/O

fruit = int(input())

if fruit / 2 >= 2 and (fruit % 2 == 1 or fruit % 3 == 2):

print('apples')

else:

print('oranges')

Logical Operators

True or False

Have you been to Nepal and Nigeria?

Have you been to Nepal or Nigeria?

Are you not had coffee or tea this morning?

Do we have Monday and not Tuesday off for Labor Day?

Objective: Logical Operators

What are they?

Why are they important?

Examples

Logical Operators

Reminder: Arithmetic operators (+, -, *, /) to combine numbers

Logical operators: combine booleans

• and
• or
• not

Logical Operators: and

and returns true only if both operands are true

Practice: and

chocolate and strawberry

chocolate and chocolate

False

True

Milkshake Time!

vanilla = True

chocolate = True

strawberry = False

vanilla and strawberry

chocolate and vanilla

vanilla and chocolate

True

strawberry and strawberry

False

False

True

Logical Operators: or

or returns true if either (or both) operand is true

Sneakers

Flip Flops

Also includes this

Practice: or

biking or running

biking or biking

True

True

Outdoor Activities!

hiking = True

running = False

biking = False

hiking or running

biking or hiking

hiking or biking

True

running or biking

False

False

False

Logical Operators: not

not inverts (gives opposite value of) the value of its operand

Sneakers

Flip Flops

Not Sleep Deprived

Sleep

Deprived

Practice: not

False

True

Favorite Colors!

blue = True

red = False

green = True

not blue

not red

not green

False

How is not different from and and or?

Unary

Binary

operates on only one variable, like not

example:

not standing

operates on two variables, like and, or

examples:

brother and sister

hot or cold

Combining Operators

Remember PEMDAS? Order of operations for arithmetic operators

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Similarly...

PNAO!

(Parentheses, not, and, or)

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Practice: Combining Logical Operators

True

False

True and not False

(False or True) and False

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not (True or False) or True

True

Practice: Combining Operators

True

False

Animals on a Farm!

dog = False

chicken = True

sheep = True

not dog or not chicken and sheep

chicken and dog or not sheep

dog and not sheep or chicken

True

not chicken or not sheep or dog

False

Let’s Code!

https://replit.com/@csci110-01/Logical-Operators#main.py

One last note...

answer = input("What city is Fisk in?")

if answer == "nashville" or "Nashville":

print("Correct!")

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Find the bug!

One last note...

answer = input("What city is Fisk in?")

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if answer == "nashville" or "Nashville":

print("Correct!")

Evaluates this first

One last note...

answer = input("What city is Fisk in?")

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if answer == "nashville" or "Nashville":

print("Correct!")

then evaluates this???

One last note...

answer = input("What city is Fisk in?")

if answer == "nashville" or "Nashville":

print("Correct!")

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Python considers "" (empty string) to be FALSE

Python considers all other strings to be TRUE

One last note...

answer = input("What city is Fisk in?")

if answer == "nashville" or "Nashville":

print("Correct!")

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Because OR only needs one condition to be True,

this entire statement will always be True

One last note...

answer = input("What city is Fisk in?")

if answer == "nashville" or answer == "Nashville":

print("Correct!")

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THIS IS RIGHT

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Review: Logical Operators

What are they?

Operators that combine booleans

and: True only if both operands are True

or: True if either (or both) operand is True

not: Inverts value of its operand

Why are they important?

Enable programs to make decisions based on multiple conditions

Questions?