Comments in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of code with inline comments

What is the output of this Python code with inline comments?

Python

x = 5  # assign 5 to x
# next line multiplies x by 2
y = x * 2
print(y)  # print the value of y

A 5

B 10

C SyntaxError

D null

💡 Hint

Look at the calculation done on x before printing y.

The comment lines do not affect the code execution. x is 5, y is x*2 which is 10, so print(y) outputs 10.

❓ Predict Output

intermediate

Effect of comments on code execution

What will be printed by this code?

Python

a = 3
# a = 10
print(a)

A SyntaxError

B 10

C 3

D null

💡 Hint

Check which line is commented out.

The line 'a = 10' is commented out, so it does not run. a remains 3, so print(a) outputs 3.

❓ Predict Output

advanced

Output with multi-line string used as comment

What is the output of this code?

Python

'''
This is a multi-line string
used as a comment
'''
print('Hello')

A SyntaxError

B

This is a multi-line string
used as a comment
Hello

C null

D Hello

💡 Hint

Multi-line strings not assigned to a variable are ignored by Python.

The triple quotes create a multi-line string that is not assigned or used, so it acts like a comment. Only 'Hello' is printed.

❓ Predict Output

advanced

Effect of comments inside code block

What will this code print?

Python

for i in range(3):
    # print(i)
    print(i + 1)

A

1
2
3

B

0
1
2

C SyntaxError

D null

💡 Hint

Look at which print statement is active inside the loop.

The first print is commented out, so only print(i + 1) runs, printing 1, 2, 3 on separate lines.

🧠 Conceptual

expert

Identifying error caused by misplaced comment

Which option will cause a SyntaxError due to incorrect comment placement?

A print(#'Hello')

B #print('Hello')

C print('Hello') # This is a comment

D print('Hello')

💡 Hint

Comments cannot start inside a string or expression.

Option A tries to start a comment inside the parentheses before the string ends, causing a SyntaxError.