Comparison operators in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of chained comparison

What is the output of this Python code?

Python

x = 5
result = 3 < x <= 5
print(result)

A True

B TypeError

C SyntaxError

D False

💡 Hint

Remember that chained comparisons check all parts together.

The expression 3 < x <= 5 checks if x is greater than 3 and less than or equal to 5. Since x is 5, both conditions are true, so the result is True.

❓ Predict Output

intermediate

Output of equality and identity

What is the output of this code snippet?

Python

a = [1, 2, 3]
b = a
c = a[:]
print(a == b, a is b, a == c, a is c)

A False False False False

B True False True False

C False True False True

D True True True False

💡 Hint

Remember that '==' checks value equality, 'is' checks if two variables point to the same object.

a and b point to the same list, so a is b is True. a and c have the same contents but are different objects, so a == c is True but a is c is False.

❓ Predict Output

advanced

Output of mixed type comparison

What happens when you run this code?

Python

print(5 < '10')

A False

B TypeError

C SyntaxError

D True

💡 Hint

Think about comparing different data types in Python 3.

In Python 3, comparing int and str with < raises a TypeError because these types cannot be ordered.

❓ Predict Output

advanced

Output of complex boolean comparison

What is the output of this code?

Python

x = 10
y = 20
print(x < y and y < 30 or x > 15)

A SyntaxError

B False

C True

D TypeError

💡 Hint

Remember the order of operations for 'and' and 'or'.

x < y is True, y < 30 is True, so 'x < y and y < 30' is True. The 'or x > 15' part is False, but True or False is True.

❓ Predict Output

expert

Output of comparison with custom class

What is the output of this code?

Python

class Number:
    def __init__(self, value):
        self.value = value
    def __lt__(self, other):
        return self.value > other.value

n1 = Number(5)
n2 = Number(3)
print(n1 < n2)

A True

B False

C TypeError

D AttributeError

💡 Hint

Look carefully at the __lt__ method implementation.

The __lt__ method is reversed: it returns True if self.value is greater than other.value. Since 5 > 3, n1 < n2 returns True.

Practice

1. Which of the following comparison operators checks if two values are equal in Python?

easy

A. ==

B. =

C. !=

D. >

Solution

1. Step 1: Understand the equality operator

   The operator == is used to check if two values are equal in Python.

2. Step 2: Differentiate from assignment and other operators

   = is for assignment, != means not equal, and > means greater than.

3. Final Answer:

   == -> Option A

4. Quick Check:

   Equality check = == [OK]

Hint: Remember: double equals means equality check [OK]

Common Mistakes:

• Confusing = with ==
• Using != for equality
• Using > instead of ==

2. Which of the following is the correct syntax to check if variable x is not equal to 10 in Python?

easy

A. x != 10

B. x <> 10

C. x =! 10

D. x !== 10

Solution

1. Step 1: Identify the correct not equal operator

   In Python, != is the correct operator for 'not equal'.

2. Step 2: Recognize invalid syntax

   <> is not valid in Python, =! and !== are syntax errors.

3. Final Answer:

   x != 10 -> Option A

4. Quick Check:

   Not equal operator = != [OK]

Hint: Use != for not equal, not <> or !== [OK]

Common Mistakes:

• Using <> which is invalid in Python
• Writing =! instead of !=
• Using !== from other languages

3. What will be the output of this code?

print(5 > 3 and 2 == 2)

medium

A. SyntaxError

B. False

C. True

D. None

Solution

1. Step 1: Evaluate each comparison

   5 > 3 is True, and 2 == 2 is True.

2. Step 2: Apply the 'and' operator

   True and True results in True.

3. Final Answer:

   True -> Option C

4. Quick Check:

   Both conditions True, so output True [OK]

Hint: Both sides must be True for 'and' to be True [OK]

Common Mistakes:

• Confusing 'and' with 'or'
• Misreading comparison results
• Expecting syntax error

4. Find the error in this code snippet:

if 4 =< 5:
    print("Yes")

medium

A. Missing colon after if statement

B. The operator =< is invalid in Python

C. Indentation error in print statement

D. Variable 4 cannot be compared

Solution

1. Step 1: Check the comparison operator

   The operator =< is not valid in Python; the correct operator is <=.

2. Step 2: Verify other syntax parts

   The colon is present and indentation is correct; 4 is a valid integer literal for comparison.

3. Final Answer:

   The operator =< is invalid in Python -> Option B

4. Quick Check:

   Use <= for less than or equal [OK]

Hint: Remember: less or equal is <=, not =< [OK]

Common Mistakes:

• Swapping operator symbols
• Missing colon
• Incorrect indentation

5. You want to check if a number n is between 10 and 20 inclusive. Which expression correctly uses comparison operators in Python?

hard

A. n > 10 or n < 20

B. 10 < n < 20

C. n >= 10 and n < 20

D. 10 <= n <= 20

Solution

1. Step 1: Understand inclusive range check

   Inclusive means n can be equal to 10 or 20, so use <= operators.

2. Step 2: Evaluate each option

   10 <= n <= 20 uses chained comparison which is correct and concise. 10 < n < 20 excludes 10 and 20. n >= 10 and n < 20 excludes 20. n > 10 or n < 20 uses 'or' which is incorrect for range check.

3. Final Answer:

   10 <= n <= 20 -> Option D

4. Quick Check:

   Use chained <= for inclusive range [OK]

Hint: Use chained comparisons for range checks [OK]

Common Mistakes:

• Using < instead of <=
• Using 'or' instead of 'and'
• Not including boundary values