Mostly asked Python Interview Questions - 2021.

Python interview questions 

1. How Python different from other programming language ?
   1. Python has high-level built-in datatypes.
   2. Python is dynamically typed language.
   3. Python programs are 3-5 times shorter than other languages like Java.
   4. Python run slower than other languages like Java.
   
   
2. What is Monkey patching in Python ?
   1. Monkey patching refers to run-time modifications in class or modules in Python.
   2. It is good for testing or mocking out behavior.
   3.In general, it is referred to add, modify or suppress the default behavior of class or modules during runtime without changing the original source code.


3. What is the difference b/w list and tuple in Python ?
   

Parameter	List	Tuple
Memory	It consume more memory.	It consume less memory.
Mutable	Lists are mutable.	Tuples are immutable.
Iteration	List iterations are time consuming.	Tuple iterations are faster.
Built-in	List has many built-in methods.	Tuple doesn't have many built-in methods.











4. Why we call Python an interpreted language ?
   Ans: Because Python code doesn't need to be compiled before running the code. Instead of compiler Python use interpreter to convert code into machine understanding byte code.
5. What are the built-in types in Python?
   Ans: Python Built-in Datatypes List, Tuple, Dictionary, Set, and Frozenset.
   
6. How garbage collection is done in Python ?
   Ans: Garbage collection done during runtime. It get triggered when the object reference count reaches to zero.
7. What are decorators in Python ?
   Ans: Decorators in Python is a function that takes another function as argument and also return a function.
8. What is Self in Python ?
   Ans: Self in Python is instance of a class. We can access the methods and attributes of that class.
9. What is __init__ method in Python ?
   Ans: __init__ method is a type of constructor in Python. It is used to assign values to data members when object of that class created.
10. What is break, continue and pass in Python ?
    Ans: Break - It is used to stop the flow of loops in Python.
    Continue - It is used to continue the flow and skip the remaining statements of loops.
    Pass - Pass is generally used to create a empty method or class in Python.
11. What is slice in Python ?
    Ans: Slicing is used to get the part of List, String, Tuple etc. We can also modify or Delete the items of mutable datatypes in Python.
12. What are namespaces in Python ? Why are they used ?
    Ans: In namespaces system every object has a unique name in Python. It is a way to implement scope. 
    There are three types of namespaces in Python- Local namespaces, Global namespaces and Built-in namespaces.
    Local namespaces: It is used to store the object of local variables.
    Global namespaces: It is used to store the object of Global functions and variables.
    Built-in namespaces: It is used to store the object of Built-in datatypes.
    
13. What is lambda in Python? Why it is used ?
    Ans: Lambda function is also called Anonymous Function. It can be defined without name or one line function.
    Example: addTwoNumbers = lambda a, b : a + b
                     print(addTwoNumbers(1, 2))
    Output : 3










14. What is pickling and unpickling in Python ?
    Ans: Pickling and Unpickling refers to storing a Python objects in a file/database. Also, referred, as Serializing and De-Serializing of Python objects into byte streams. 
15. What are generators in Python ?
    Ans: Generators is used to create a user defined iterators functions. Generator doesn't return a single value, return a sequence of values. In generator yield statement is used in place of return.
    Example: def count_generator():
                          n = 1
                          yield n
                          n += 1
                          yield n
    countObj = count_generator()
    next(countObj)
    >>> 1
    next(countObj)
    >>> 2  
16. Why we use *args and **kwargs in Python ?
    Ans: These are used to pass variable number or parameters or arguments to Python functions. They add flexibility to pass variable arguments to functions.
    *args : It sends a list of values to python function.
    **kwargs : It sends dictionary of values
    
    
17. Python support negative indexes e.g arr[-1] ?
    Yes, Python support negative index values.
    Examples :-
    1. -1 gives the last element of the array.
    2. -2 gives the second last element of an array.
    
    
18. What is main() function in Python ? How can we invoke it ?
    Ans:  Main function is like the entry point of execution for any  program. However, Python interpreter execute the code from the first line.
    
    
19. What are Keywords in Python ? How many keywords are there in Python ?
    Ans:  Keywords are predefined and reserved words in Python. There are around 35 keywords in Python.
    In Python console :-
    >>> help("keywords")
    Here is a list of the Python keywords.  Enter any keyword to get more help.
    

False	Break	for	not
None	class	from	or
True	continue	global	pass
def	if	raise	and
del	import	return	as
elif	in	try	assert
else	is	while	async
except	lambda	with	await
finally	nonlocal	yield	__peg_parser__












20. Is Python a case sensitive language ?
    Ans: Yes, Python is case sensitive language.

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