Top 40 Python Interview Questions and Answers

Are you preparing for Python interview? Whether you’re a beginner, fresh graduate or an experienced developer, it’s essential to prepare answers to Python interview questions to crack the technical rounds.

In this article, we have compiled the most frequently asked Python interview questions with the best possible answers. We’ve covered everything from basic to advanced topics—including strings, data structures, OOPs, multithreading, and more.

We have also provided sample coding for better understanding. So, are you ready to level up your Python skills? Let’s dive in, starting from the question number 1! 👇

1. What is Python?

Python is a high-level, interpreted, interactive, general-purpose and object-oriented programming language. Guido van Rossum developed it at Centrum Wiskunde & Informatica (CWI) in the Netherlands. Its first version was released in 1991. Python is known for its simple syntax and readability, making it easy to learn and use. It uses English keywords, concise codes, simple and easy-to-use syntax. Hence, Python is an excellent computer programming language to learn for beginners.

2. Why do companies prefer Python?

Refer to the Python tutorial for answer.

3. What are the key features of Python?

The key features of Python programming language are as follows:

• Easy to learn and use
• Interpreted language
• Expressive language
• Platform independent scripted language
• Free and open source
• Object-oriented language
• Supports interactive mode that allows interacting testing and debugging of code snippets.
• Dynamically typed language
• Supports functional and structural programming as well as OOPs.
• GUI support
• Database support

To get more information about these features, please refer to this tutorial: 16 key features of Python

4. What are the benefits of using Python?

There are the following advantages of using Python. They are as follows:

• Simple to read, understand, and use
• Interpreted language
• Extensive support libraries
• Free and open source
• Dynamically typed
• Portability
• Broad supportive community development
• Component integration
• Presence of third party module
• User-friendly data structure

For more information, please go to this tutorial: Advantages of Python

5. What are the disadvantages of using Python?

The disadvantages of using Python are as follows:

• Slow execution speed
• Weak in mobile computing
• Memory consumption
• Database access
• Runtime errors

6. What are the applications of Python?

Python can be used in the following application areas. They are as:

• Developing web applications
• Desktop GUI applications
• Data analysis
• Machine learning and artificial intelligence applications
• Statistics
• Cloud computing
• Software development
• Scientific and Numeric
• Business applications
• Audio or Video-based applications

Please refer to the top 16 applications of Python for more information.

7. Is Python compiled or interpreted language?

Python is considered an interpreted language because the Python interpreter executes the code line by line, rather than compiling it into machine code all at once like in other compiled languages such as Java or C++. However, Python does go through an internal compilation step, which is completely hidden from the programmer.

When you run a Python program, the .py source code is first compiled into byte code, which creates a file with extension .pyc. This byte code is then interpreted by the Python Virtual Machine (PVM).

Yes, Python is loosely typed (also known as dynamically typed) language. This means that you don’t need to declare the data type of a variable when you create it. The interpreter automatically determines the type at runtime based on the value assigned to the variable. For example:

x = 10        # x is an integer.
x = "hello"   # now x is a string.

In the above Python code, we have reassigned a variable to a value of a different type without any error. This flexibility is why Python is called a loosely typed or dynamically typed language.

9. How to start a new block in Python?

In Python, we can start a new block of code using indentation. An indentation refers to white spaces to define the block of code. Python does not use curly braces {} around the block of code, unlike other programming languages, such as Java. For example:

if x > 0:
    print("x is positive")  # This line is part of the if block.
    print("This is still inside the block")
print("This is outside the block")

In this example, indentation is usually 4 spaces. All lines in the same block must have the same indentation level. Indentation is mandatory in Python. Improper indentation will cause an error.

Basic Python Interview Questions with Answers

Here, we have compiled the basic Python interview questions and answers based on the topics like tokens, variables, and data types.👇

10. What is token in Python? How many tokens are in the below program?

x = int(input("Enter your first number = "))

A token is the smallest individual unit, or element in the Python program, which is identified by the interpreter. Python language supports five types of tokens: keywords, identifiers, literals, operators, and punctuators (separators).

In the above example, there are nine tokens:

• x
• =
• int
• (
• input
• (
• “Enter your first number = “
• )
• )

11. What is a variable in Python? How to determine the data type of a particular variable?

A variable in Python is a reserved memory location to store a value, such as a number, text, object, or anything. We use type() function to get the data type of a variable. For example:

num = 100
print(type(num))

Output:
      <class 'int'>

• my_var
• 2ndValue
• _temp
• class
• userName
• user-name
• _0_0_9

Valid variable names are my_var, _temp, userName, and _0_0_9.

13. What is data type in Python?

A data type in Python defines a specific type of value that a variable can store.

14. What are the built-in data types in Python?

Python has several built-in data types:

• Number
• Boolean
• None
• String
• List
• Tuple
• Dictionary
• Set

15. What is dynamic data type in Python?

Data types are dynamic in Python, which means that we don’t need to define the data type of variable explicitly. The data type of a variable is determined in accordance with the value assigned to the variable. The change in value leads to the change in the variable’s type. Thus, the same variable can hold the values of different data types at different times during the execution of a program.

16. How can you switch variables in Python?

In Python, you can swap (switch) the values of two variables easily without using a temporary variable. Python supports tuple unpacking, which makes this very simple. For example:

a = 10
b = 20
# Swapping values
a, b = b, a

print("a =", a)  # Output: a = 20
print("b =", b)  # Output: b = 10

In this example, the right side (b, a) creates a tuple of values. The left side (a, b) unpacks them into the variables. So, values of variables are switched in just one line.

17. What is the difference between mutable and immutable data types in Python?

An object that value or data can change during the execution of a program is called mutable data type. The values of a mutable object can change after it has created. The examples of Python’s mutable data types are: list, set, dictionary, bytearray, and array.

An object that value or data cannot change in its place after initialization or assignment during the execution of a program is called immutable data type. The values of an immutable object cannot change after it has created. Examples of Python’s immutable data types or objects are: strings, tuples, etc.

18. What are global and local variables in Python?

A variable defined outside all functions in a program is called global variable in Python. It will be visible everywhere in the entire Python code. You can access a global variable throughout the Python program.

A local variable is a variable that is defined inside the body of the function or in the local scope. It is accessible only within the function where it is defined and exists in the memory as long as the function is executing.

Python Operators – Interview Questions

Now, you will get the Python interview questions and answers based on the operators. So, let’s dive in, starting from the question number 19! 👇

Python supports several types of operators such as:

• Arithmetic operators: +, -, *, /, //, %, **
• Comparison (Relational) operators: ==, !=, >, <, >=, <=
• Assignment operators: =, +=, -=, *=, /=, etc.
• Logical operators: and, or, not
• Bitwise operators: &, |, ^, ~, <<, >>
• Membership operators: in, not in
• Identity operators: is, is not

20. Explain the difference between == and is in Python.

The equality operator (==) is used to check if values are equal or not. The identity operator (is) is used to check if two variables refer to the same object in memory location.

21. What are logical operators in Python?

In Python, logical operators are binary operators which are used to combine two or more simple conditional or relational expressions. There are three types of logical operators: and, or, and not.

22. What are identity operators in Python?

Identity operators in Python are special type of binary operators that compare the memory locations of two objects. Python language supports two types of identity operators:

• is -> Returns True if both refer to the same object in the memory.
• is not -> Returns True if they do not refer to the same object in the memory.

23. What are membership operators in Python?

Membership operators are those binary operators that check whether a value exists in a sequence, such as string, list, tuple, set, or dictionary. Python supports two types of membership operators:

• in – Returns True true if the specified value is present in the specified sequence.
• not in – Returns True true if the specified value is not found in the specified sequence.

24. What is ternary operator in Python?

In Python, a ternary operator is a one-line shorthand operator for an if-else statement. It allows you to assign a value to a variable based on a condition in a single line of code. The basic syntax is:

variable = true_value if conditional_expression else false_value

Conditional Statements – Interview Questions

In this section, you’ll find some of the most frequently asked Python interview questions and answers based on conditional statements, such as if-else, loops, break, continue, and more.

25. Draw the flowchart diagram of if-else statement in Python.

The flowchart diagram for two-way if-else statement in Python is shown below in the figure.

26. What is a loop in Python?

A loop in Python is a control structure that repeatedly executes a statement or a group of statements until a specific condition is true.

27. How does while loop work in Python? Explain it with example.

A while loop works in five simple steps:

1. First, the initialization part is executed. It is basically a loop counter variable that sets the starting value of the variable controlling the loop.
2. Next, Python evaluates the test condition inside the parentheses of the while statement.
3. When the test condition is true, the loop body executes. After the execution of loop body, the control goes to increment or decrement part. It will increment or decrement the value of loop control variable by one.
4. After executing increment or decrement part, the test condition once again evaluates to true. If the specified condition is true, the loop body executes once again. This process continues by the Python interpreter until the condition or expression finally becomes false.
5. Once the test condition is false, the loop terminates and the program control immediately transfers out of the loop.

Example:

# Program to display numbers from 1 to 5.
i = 1 # Initialization.
while i <= 5:
    print('Current value of i is ',i)
    i = i + 1 # Increment by 1.

28. Explain for loop in Python with the help of an example.

For loop in Python is a conditional looping structure that executes a statement or a block of statements a certain number of times. We use a for loop in the program when we know exactly how many times we have to repeat a loop. For example, the following code prints “Hello Python” five times.

# Program code to print a statement five times.
for count in range(0, 5):
    print('Hello Python')

29. What is the difference between break statement and continue statement?

There are two main differences between break statement and continue statement. They are:

• Break statement terminates or breaks the loop, whereas continue statement escapes from the current iteration.
• Break statement transfers the control to the statement (if any) immediately following the loop. While, continue statement transfers the control back to the start of the loop for the next iteration.

30. What is the use of pass statement in Python?

The pass statement is a simple statement in Python that tells the Python interpreter to ‘do nothing’. The use of pass statement in Python is as:

• You can use pass statement when a statement is syntactically required, but we do not want to use any executable statement at its place.
• You use the pass statement to hold the place of code that is not ready or incomplete code yet.
• Normally, the pass statement is used within the code block under the conditional if statement or while statement.
• We mostly use the pass statement to create empty or null classes or functions.

Functions – Interview Questions and Answers

Now, you will find the most frequently asked Python interview questions and answers based on functions and strings. Keep going to enhance your Python interview preparation!

31. Is Python pass by value or pass by reference?

Python is pass by object reference. We know that almost everything in Python is an object. Thus, every value is an object in Python, and all values contain references to actual objects. So, object references that refer to the actual objects are passed by value. We call this mechanism as pass by object reference in Python.

32. What is the use of global keyword in Python programming?

Global keyword is used to make a variable global inside the function.

33. What is lambda function in Python? Give an example of it.

A function that is defined without a name is called lambda function in Python. It is also called anonymous function, which means a function without a name (i.e. nameless function). An example of lambda function is given below:

# Program to calculate the square of a number.
squared = lambda num: num ** 2 # lambda function with lambda keyword.
print(squared(20)) # output 400

34. What is recursion in Python? How to stop it?

Recursion in Python is a process in which a function calls itself one or more times in its body. It may call itself directly or indirectly. We can stop recursion by defining base case or terminal case. Base case is basically a condition that stops the recursion and prevents infinite calls.

String – Interview Questions

35. What is string in Python? How will you create it?

A string is a sequence of characters, which consist of one or more letters, numbers, punctuation marks, and spaces. It is an immutable object, meaning once we create it, we can no longer change it.

To create strings or a string literal in Python, you must enclose it in either single (‘), double (“) or triple (”’ or “””) quotes and assign it to a variable.

36. How to find length of string in Python without using len() function?

Let’s take an example in which we will calculate the length of string without using len() function.

def main():
    user_str = input('Enter a string: ')
    count_char = 0
    for ch in user_str:
        count_char += 1
    print(f"Length of entered string is '{count_char}'")

main() # calling function.

37. What are common ways to concatenate strings in Python?

There are five convenient ways to concatenate strings. They are as:

• Using + operator
• Using join() method
• By using % operator
• By using format() function
• Using f-string (Literal String Interpolation)

For more information, go to this tutorial: String concatenation in Python.

38. What is string slicing in Python? How to perform string slicing?

String slicing is a technique in which you can obtain a sub-part of the original string by specifying a range of index numbers separated by a colon. There are basically two ways to perform string slicing. They are:

• Using slice() method
• Using array slice operator

39. What are ways to format strings in Python?

There are mainly three ways to format strings in Python.

• Formatting with % Operator.
• Formatting with format() string method.
• Formatting with string literals, called f-strings

Refer to String formatting to get more knowledge.

40. How to check whether two strings are equal?

In Python, you can check whether two strings are equal using the equality operator (==). For example:

str1 = "hello"
str2 = "hello"

if str1 == str2:
    print("Strings are equal")
else:
    print("Strings are not equal")

In this example, the equality operator (==) checks that if the values of the strings are the same. Since str1 == str2 are True, it will print “Strings are equal”.

If you want to check if two strings are the same object in memory, you can use is membership operator. However, it is usually not needed for string comparison.

I hope that you will have understood the best possible answers of Python interview questions. To crack Python interview, it’s important to understand both basic and advanced concepts of Python. By practicing common interview questions, you’ll be more confident and answer any interview question that comes your way. Keep learning and coding to do your best in the interview!