Python Interview Questions

 

1. What is Python?

Python is a high-level, interpreted, general-purpose programming language. Being a general-purpose language, it can be used to build almost any type of application with the right tools/libraries. Additionally, python supports objects, modules, threads, exception-handling and automatic memory management which help in modelling real-world problems and building applications to solve these problems.

2. What are the benefits of using Python?

Python is a general-purpose programming language that has simple, easy-to-learn syntax which emphasizes readability and therefore reduces the cost of program maintenance. Moreover, the language is capable of scripting, completely open-source and supports third-party packages encouraging modularity and code-reuse.
Its high-level data structures, combined with dynamic typing and dynamic binding, attract a huge community of developers for Rapid Application Development and deployment. know more at Python online training

3. What is a dynamically typed language?

Before we understand what a dynamically typed language, we should learn about what typing is. Typing refers to type-checking in programming languages. In a strongly-typed  language, such as Python, "1" + 2 will result in a type error, since these languages don't allow for "type-coercion" (implicit conversion of data types). On the other hand, a weakly-typed  language, such as Javascript, will simply output "12" as result.

Type-checking can be done at two stages -

  • Static - Data Types are checked before execution.
  • Dynamic - Data Types are checked during execution.
Python being an interpreted language, executes each statement line by line and thus type-checking is done on the fly, during execution. Hence, Python is a Dynamically Typed language.

4. What is an Interpreted language?

An Interpreted language executes its statements line by line. Languages such as Python, Javascript, R, PHP and Ruby are prime examples of Interpreted languages. Programs written in an interpreted language runs directly from the source code, with no intermediary compilation step.

5. What is PEP 8 and why is it important?

PEP stands for Python Enhancement Proposal. A PEP is an official design document providing information to the Python Community, or describing a new feature for Python or its processes. PEP 8 is especially important since it documents the style guidelines for Python Code. Apparently contributing in the Python open-source community requires you to follow these style guidelines sincerely and strictly. know more at Python training

6. How is memory managed in Python?

Memory management in Python is handled by the Python Memory Manager. The memory allocated by the manager is in form of a private heap space dedicated for Python. All Python objects are stored in this heap and being private, it is inaccessible to the programmer. Though, python does provide some core API functions to work upon the private heap space.
Additionally, Python has an in-built garbage collection to recycle the unused memory for the private heap space.

7. What are Python namespaces? Why are they used?

A namespace in Python ensures that object names in a program are unique and can be used without any conflict. Python implements these namespaces as dictionaries with 'name as key' mapped to a corresponding 'object as value'. This allows for multiple namespaces to use the same name and map it to a separate object. A few examples of namespaces are as follows:

  • Local Namespace includes local names inside a function. the namespace is temporarily created for a function call and gets cleared when the function returns.
  • Global Namespace includes names from various imported packages/ modules that is being used in the current project. This namespace is created when the package is imported in the script and lasts until the execution of the script.
  • Built-in Namespace includes built-in functions of core Python and built-in names for various types of exceptions.
Lifecycle of a namespace depends upon the scope of objects they are mapped to. If the scope of an object ends, the lifecycle of that namespace comes to an end. Hence, it isn't possible to access inner namespace objects from an outer namespace.

8. What is Scope in Python?

Every object in Python functions within a scope. A scope is a block of code where an object in Python remains relevant. Namespaces uniquely identify all the objects inside a program. However, these namespaces also have a scope defined for them where you could use their objects without any prefix. A few examples of scope created during code execution in Python are as follows:

  • A local scope refers to the local objects available in the current function.
  • A global scope refers to the objects available throught the code execution since their inception.
  • A module-level scope refers to the global objects of the current module accessible in the program.
  • An outermost scope refers to all the built-in names callable in the program. The objects in this scope are searched last to find the name referenced. know more at Python online training from India
Note: Local scope objects can be synced with global scope objects using keywords such as global.

9. What is Scope Resolution in Python?

Sometimes objects within the same scope have the same name but function differently. In such cases, scope resolution comes into play in Python automatically. A few examples of such behaviour are:

  • Python modules namely 'math' and 'cmath' have a lot of functions that are common to both of them - log10(), acos(), exp() etc. To resolve this amiguity, it is necessary to prefix them with their respective module, like math.exp() and cmath.exp().
  • Consider the code below, an object temp has been initialized to 10 globally and then to 20 on function call. However, the function call didn't change the value of the temp globally. Here, we can observe that Python draws a clear line between global and local variables

  • Q10. What is namespace in Python?

    Ans: A namespace is a naming system used to make sure that names are unique to avoid naming conflicts.

    Q11. What is PYTHONPATH?

    Ans: It is an environment variable which is used when a module is imported. Whenever a module is imported, PYTHONPATH is also looked up to check for the presence of the imported modules in various directories. The interpreter uses it to determine which module to load.

    Q12. What are python modules? Name some commonly used built-in modules in Python?

    Ans: Python modules are files containing Python code. This code can either be functions classes or variables. A Python module is a .py file containing executable code.

    Some of the commonly used built-in modules are:

    • os
    • sys
    • math
    • random
    • data time
    • JSON

    Q13.What are local variables and global variables in Python?

    Global Variables:

    Variables declared outside a function or in global space are called global variables. These variables can be accessed by any function in the program.

    Local Variables:

    Any variable declared inside a function is known as a local variable. This variable is present in the local space and not in the global space.

    Example:

    1
    2
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    5
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    a=2
    def add():
    b=3
    c=a+b
    print(c)
    add()

    Output: 5

    When you try to access the local variable outside the function add(), it will throw an error.

    Q14. Is python case sensitive?

    Ans: Yes. Python is a case sensitive language.

    Q15.What is type conversion in Python?

    Ans: Type conversion refers to the conversion of one data type iinto another.

    int() – converts any data type into integer type

    float() – converts any data type into float type

    ord() – converts characters into integer

    hex() – converts integers to hexadecimal

    oct() – converts integer to octal

    tuple() – This function is used to convert to a tuple.

    set() – This function returns the type after converting to set.

    list() – This function is used to convert any data type to a list type.

    dict() – This function is used to convert a tuple of order (key,value) into a dictionary.

    str() – Used to convert integer into a string.

    complex(real,imag) – This functionconverts real numbers to complex(real,imag) number.

    Q16. How to install Python on Windows and set path variable?

    Ans: To install Python on Windows, follow the below steps:

  • Q17. Is indentation required in python?

    Ans: Indentation is necessary for Python. It specifies a block of code. All code within loops, classes, functions, etc is specified within an indented block. It is usually done using four space characters. If your code is not indented necessarily, it will not execute accurately and will throw errors as well. know more at Python online course

    Q18. What is the difference between Python Arrays and lists?

    Ans: Arrays and lists, in Python, have the same way of storing data. But, arrays can hold only a single data type elements whereas lists can hold any data type elements.

  • Q19. How do you write comments in python?

    Ans: Comments in Python start with a # character. However, alternatively at times, commenting is done using docstrings(strings enclosed within triple quotes).

    Example:

    #Comments in Python start like this
print("Comments in Python start with a #")

    Output:  Comments in Python start with a #

    Q20. What is pickling and unpickling?

    Ans: Pickle module accepts any Python object and converts it into a string representation and dumps it into a file by using dump function, this process is called pickling. While the process of retrieving original Python objects from the stored string representation 

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