Comparison operators in Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the == operator do in Python?

The == operator checks if two values are equal. It returns True if they are the same, and False if they are different.

beginner

What is the difference between == and != operators?

== checks if two values are equal, while != checks if two values are not equal. != returns True if values differ.

beginner

How do you check if one number is greater than another in Python?

Use the > operator. For example, 5 > 3 returns True because 5 is greater than 3.

beginner

What does the <= operator mean?

The <= operator means 'less than or equal to'. It returns True if the left value is smaller than or exactly equal to the right value.

intermediate

Can comparison operators be used with strings in Python? How?

Yes, comparison operators can compare strings based on alphabetical order. For example, 'apple' < 'banana' returns True because 'apple' comes before 'banana'.

What will 7 == 7 return in Python?

A False

B True

C 7

D Error

== checks if two values are equal. Since 7 equals 7, it returns True.

Which operator checks if two values are NOT equal?

A !=

B ==

C >

D <=

!= means 'not equal to' and returns True if values differ.

What does 5 <= 5 evaluate to?

A False

B 5

C True

D Error

<= means 'less than or equal to'. Since 5 equals 5, it returns True.

Which comparison operator means 'greater than'?

A >

B ==

C <

D !=

> means 'greater than'.

What will 'cat' < 'dog' return?

A False

B Depends on Python version

C Error

D True

Strings are compared alphabetically. 'cat' comes before 'dog', so it returns True.

Explain how to use comparison operators to compare two numbers in Python.

Think about checking if numbers are equal, different, or which one is bigger.

Describe how comparison operators work with strings in Python.

Strings are compared like words in a dictionary.

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