Boolean values (True and False) in Python

Introduction

Boolean values help us decide between two choices: yes or no, true or false.

Checking if a light is on or off.

Deciding if a user is logged in or not.

Testing if a number is bigger than another.

Verifying if a door is locked or unlocked.

Syntax

Python

True
False

Boolean values always start with a capital letter in Python.

They represent the idea of yes/no or on/off in programs.

Examples

Here, we say it is raining (True) and not sunny (False).

Python

is_raining = True
is_sunny = False

If the light is on (True), we print a message.

Python

light_on = True
if light_on:
    print("The room is bright")

Sample Program

This program checks if you are hungry. If yes (True), it suggests eating.

Python

is_hungry = True
if is_hungry:
    print("Time to eat!")
else:
    print("Not hungry now.")

Important Notes

Boolean values are often used in conditions to control what the program does.

Remember, True and False are special words in Python, not strings.

Summary

Boolean values are True or False.

They help programs make decisions.

Use them to check conditions simply.

Practice

1. Which of the following is a Boolean value in Python?

easy

A. yes

B. "True"

C. True

D. 1

Solution

1. Step 1: Understand Boolean values

   Boolean values in Python are exactly True or False, not strings or numbers.

2. Step 2: Identify the correct Boolean

   True is the Boolean value True. "yes", "True", and 1 are not Boolean types.

3. Final Answer:

   True -> Option C

4. Quick Check:

   Boolean = True or False [OK]

Hint: Look for exact True or False without quotes [OK]

Common Mistakes:

• Confusing string "True" with Boolean True
• Using numbers like 1 as Boolean
• Thinking any word means Boolean

2. Which of these is the correct way to write a Boolean value in Python?

easy

A. False

B. true

C. FALSE

D. false

Solution

1. Step 1: Recall Python Boolean syntax

   Python Boolean values start with a capital letter: True and False.

2. Step 2: Check each option

   Only False, False, is correctly capitalized. Others are lowercase or all caps, which are invalid.

3. Final Answer:

   False -> Option A

4. Quick Check:

   Booleans start with uppercase [OK]

Hint: Booleans start with uppercase T or F [OK]

Common Mistakes:

• Writing booleans in lowercase
• Using all uppercase letters
• Confusing with strings

3. What will be the output of this code?

print(5 > 3)

medium

A. Error

B. False

C. 5 > 3

D. True

Solution

1. Step 1: Evaluate the comparison

   The expression 5 > 3 checks if 5 is greater than 3, which is true.

2. Step 2: Understand print output

   Printing a Boolean expression prints True or False accordingly. Here it prints True.

3. Final Answer:

   True -> Option D

4. Quick Check:

   5 > 3 is True [OK]

Hint: Compare values; print shows True or False [OK]

Common Mistakes:

• Thinking it prints the expression as text
• Confusing True with string 'True'
• Expecting an error from comparison

4. Find the error in this code:

if True = 5:
    print("Yes")

medium

A. Assignment used instead of comparison

B. Missing colon after if

C. True cannot be used in conditions

D. Indentation error

Solution

1. Step 1: Check the if statement syntax

   The code uses = which is assignment, not comparison. Conditions need ==.

2. Step 2: Identify the error type

   Using = in an if condition causes a syntax error because assignment is not allowed there.

3. Final Answer:

   Assignment used instead of comparison -> Option A

4. Quick Check:

   Use == for comparison, not = [OK]

Hint: Use == to compare, = is for assigning [OK]

Common Mistakes:

• Using = instead of ==
• Forgetting colon after if
• Thinking True can't be in conditions

5. You want to check if a number n is NOT zero using Boolean logic. Which code correctly prints True if n is not zero, otherwise False?

hard

A. print(n == 0)

B. print(n != 0)

C. print(n = 0)

D. print(not n)

Solution

1. Step 1: Understand the condition

   We want to print True if n is NOT zero, so the condition should check n != 0.

2. Step 2: Evaluate each option

   print(n == 0) prints True if n is zero (wrong). print(n != 0) correctly prints True if n is not zero. print(n = 0) causes a syntax error (invalid syntax). print(not n) prints True if n is zero (because not 0 is True), so it's opposite.

3. Final Answer:

   print(n != 0) -> Option B

4. Quick Check:

   Use != to check not equal [OK]

Hint: Use != to check not equal, not = [OK]

Common Mistakes:

• Using = instead of !=
• Confusing not n with n != 0
• Using == instead of !=