Boolean

A Boolean value is either true or false.
A Boolean expression produces a Boolean value (true or false) when evaluated.

Conditional ("if") statements

Affect the sequential flow of control by executing different statements based on the value of a Boolean expression.

IF (condition)
{
	<block of statements>
}

The code in <block of statements> is executed if the Boolean expression condition evaluates to true; no action is taken if condition evaluates to false.

IF (condition)
{
	<block of statements>
}
ELSE
{
	<second block of statements>
}

The code in the first <block of statements> is executed if the Boolean expression condition evaluates to true; otherwise, the code in <second block of statements> is executed.

Example: Calculate the sum of 2 numbers. If the sum is greater than 10, display 10; otherwise, display the sum.

num1 = INPUT
num2 = INPUT
sum = num1 + num2
IF (sum > 10)
{
	DISPLAY (10)
}
ELSE
{
	DISPLAY (sum)
}

---------------------------------------------------------------------------

NameError                                 Traceback (most recent call last)

/tmp/ipykernel_1445/770612961.py in <module>
----> 1 num1 = INPUT
      2 num2 = INPUT
      3 sum = num1 + num2
      4 IF (sum > 10)
      5 {


NameError: name 'INPUT' is not defined

Hack 1

Add a variable that represents an age.
Add an ‘if’ and ‘print’ function that says “You are an adult” if your age is greater than or equal to 18.
Make a function that prints “You are a minor” with the else function.

age = int(input("how old are u"))

if age >= 18:
    print("you are an adult")
else:
    print("you are a minor")
 

you are a minor

Relational operators:

Used to test the relationship between 2 variables, expressions, or values. These relational operators are used for comparisons and they evaluate to a Boolean value (true or false).

Ex. a == b evaluates to true if a and b are equal, otherwise evaluates to false

a == b (equals)
a != b (not equal to)
a > b (greater than)
a < b (less than)
a >= b (greater than or equal to)
a <= b (less than or equal to)

Example: The legal age to work in California is 14 years old. How would we write a Boolean expression to check if someone is at least 14 years old?

age >= 14

Example: Write a Boolean expression to check if the average of height1, height2, and height3 is at least 65 inches.

(height1 + height2 + height3) / 3 >= 65

Hack 2

Make a variable called ‘is_raining’ and set it to ‘True”.
Make an if statement that prints “Bring an umbrella!” if it is true
Make an else statement that says “The weather is clear”.

is_raining = bool(input("is it raining? (True/False)"))

if is_raining == True: 
    print("Bring an umbrella")
else:
    print("The weather is clear")

Bring an umbrella

Logical operators:

Used to evaluate multiple conditions to produce a single Boolean value.

NOT evaluates to true if condition is false, otherwise evaluates to false
AND evaluates to true if both conditions are true, otherwise evaluates to false
OR evaluates to true if either condition is true or if both conditions are true, otherwise evaluates to false

Example: You win the game if you score at least 10 points and have 5 lives left or if you score at least 50 points and have more than 0 lives left. Write the Boolean expression for this scenario.

(score >= 10 AND lives == 5) OR (score == 50 AND lives > 0)

Relational and logical operators:

Example: These expressions are all different but will produce the same result.

age >= 16
age > 16 OR age == 16
NOT age < 16

Hack 3

Make a function to randomize numbers between 0 and 100 to be assigned to variables a and b using random.randint
Print the values of the variables
Print the relationship of the variables; a is more than, same as, or less than b

from random import randint

a = randint(1, 100)
b = randint(1, 100)
print(a)
print(b)
if a > b:
    print("a is greater than b")
elif a < b:
    print("b is greater than a")
else:
    print("b is equal to a!")

75
39
a is greater than b

Homework

Criteria for above 90%:

Add more questions relating to Boolean rather than only one per topic (ideas: expand on conditional statements, relational/logical operators)
Add a way to organize the user scores (possibly some kind of leaderboard, keep track of high score vs. current score, etc. Get creative!)
Remember to test your code to make sure it functions correctly.

# Import necessary modules
import getpass
import sys

# Function to ask a question and get a response
def question_with_response(prompt, correct_answer):
    # Print the question
    print("Question: " + prompt)
    # Get user input as the response
    user_response = input("Your answer: ")
    
    # Check if the user's response is correct
    if user_response.lower() == correct_answer.lower():
        print("Correct!\n")
        return 1
    else:
        print("Incorrect. The correct answer is:", correct_answer, "\n")
        return 0

# Define the number of questions and initialize the correct answers counter
questions = 5
correct = 0

# Personalized greeting message
user_name = input("Enter your name: ")
print('Hello, ' + user_name + " running " + sys.executable)
print("You will be asked " + str(questions) + " questions.")
answer = input("Are you ready to take the test? (yes/no): ")

if answer.lower() != "yes":
    print("Test canceled.")
else:
    # Questions and answers
    correct += question_with_response("Question 1: What is a Boolean value? (true/false)", "true")
    correct += question_with_response("Question 2: What are Boolean expressions used for in programming?", "to make decisions")
    correct += question_with_response("Question 3: What is the purpose of conditional statements in programming?", "to execute code")
    correct += question_with_response("Question 4: Give an example of a relational operator.", "greater than")
    correct += question_with_response("Question 5: Give an example of a logical operator.", "and ")

    # Display the final score
    percentage_correct = (correct / questions) * 100
    print(user_name + ", you scored " + str(correct) + "/" + str(questions) + " (" + str(percentage_correct) + "%).")

Hello, aditya running /bin/python
You will be asked 5 questions.
Question: Question 1: What is a Boolean value? (true/false)
Correct!

Question: Question 2: What are Boolean expressions used for in programming?
Correct!

Question: Question 3: What is the purpose of conditional statements in programming?
Incorrect. The correct answer is: to execute code conditionally 

Question: Question 4: Give an example of a relational operator.
Incorrect. The correct answer is: greater than (>) 

Question: Question 5: Provide an example of a logical operator.
Incorrect. The correct answer is: and (&&) 

aditya, you scored 2/5 (40.0%).

Boolean, If Lesson • 18 min read

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