Python comments and variables

by WeCanCode-Author | Jan 25, 2021 | Learn, Python

Python comments and variables

Let us see about Python comments and variables which covers the below topics.

1. Python Comments
   • Single line comment
   • End of the line comments
   • Multi line comments using # ^{_{(Pound or Sharp)}}
   • Multi line comments using """ _{(3 double quotes a.k.a Multi line string)}
2. Variables
   • Declaring variables
   • Assign variables
   • re-assign variables
   • Nullify variables using None Keyword

Code Repo : https://git.io/JtnlX

Slides: https://git.io/Jtckd

We have the below topics covered as part of Python learning course.

1. Python introduction in Tamil Part 1
2. Python introduction in Tamil Part 2
3. Writing your first python program and how to execute it?
4. Python syntax, indentation and data types

Watch on YouTube: https://youtu.be/aRWq1UMYgXU

Python Comments

Comments in Python

1. Documentation using comments – It helps anyone reading the code along with the comments can easily understand the code easily and how it works. (Logical and Functional explanation).
2. _{(mostly this will be used for debugging your code, if the code is not working as expected and to find the line which cause the bug).}

How to comment and what are all the ways we can comment in Python?

Lets see what all ways we can comment in Python.

• Single line comments
• End of the line comments
• Multi line comments using # ^{_{(Pound or Sharp)}}
• Multi line comments using """ _{(3 double quotes a.k.a Multi line string)}

Single line comments

It is writing in one single line and These lines are prefixed using # ^{_{(Pound or Sharp)}}.

# This is Single line comment
# Sample program to print hello world.
print("Hello, World")
# End of my python program

End of the line comments

End of line comments, as name says it is written at end of the line along with the Python code.

Lets see an example below,

amt1 = 20
amt2 = 5
final_amt = amt1 + amt2  # Adding amt1 and amt2.

Multi line comments using #

Multi line comments using #, it is similar to Single line comment, but it is written on multiple lines prefixed with the # ^{_{(Pound or Sharp)}} symbol.

Primarily used for documenting python code or explaining the block of code below,

Its written at the top of a class or function.

Lets see an example below

#  Author: aryanz.co.in
#  Class name: calculator
#  Description:  This class is used for performing add, sub, multiply and divide. each action requires two parameters.

#  Add operation
#  Two parameters x and y
#  prints the result on the screen
def add(x, y)
          print(x + y)

Multi line comments using “””

It is same as Multi line comment using # but it is prefixed with the """ ^{_{(3 double quotes)}}.

Similar to the Multi line using #, even here we can use this for documentation.

Lets see an example below

"""  
Author: aryanz.co.in
Class name: calculator
Description:  This class is used for performing add, sub, multiply and divide. each action requires two parameters.
"""

""" Add operation
Two parameters x and y
prints the result on the screen
"""
def add(x, y)
          print(x + y)

Python Variables

What is a variable?

Variables, a placeholder or container or a memory location to store values of any type, such as string, int, float, list and etc.,

• A variable is a container for storing data/values.
• Values are assigned at the beginning of the program.
• It does not need to be declared with any particular type.
• Type can be changed at any time, after they have been initialized at the beginning. (x = 5, after few line of code assign x = “Hello”, it is possible in Python)
• Before assigning values to variables, it can be typecast to a specific type. (x = str(4))
• Most importantly variables are case sensitive. (Msg = “Hello” and msg = “Hello” both are different variables)

Variable declarations (see below).

Python Syntax and Data types

by WeCanCode-Author | Jan 15, 2021 | Learn, Python

Python Syntax and Data types

Today we are going to see about Python Syntax and Data types which consist of the following

1. Python Syntax
2. Indentation in Python
3. Best practices while writing Python program
4. Data types (In build data types in Python)

Code Repo : https://git.io/JtUqQ

Slides : https://git.io/JtUZM

In case if you have missed our previous topics

1. Python introduction in Tamil Part 1
2. Python introduction in Tamil Part 2
3. Writing your first python program and how to execute it?

Watch in youtube: https://youtu.be/ftaMRl8gdZ0

Syntax, Indentation and Best practice

Indentation is it really needed for Python?

Well to answer for it, Yes Its is very important for us to know about the indentation. because Python does not uses the curley braces ‘{‘ or ‘}’ for enclosing the statements. where as it used the indentations for it.

Key points to remember about Indentation

• Giving space or tab space at beginning of a line, is called indentation.
• In Python Indentation plays important role.
• It uses the space to determine the block of statements.
• The first line of Python code should not have indentation.(it will throw IndentationError)

Python coding best practices

Lets us see some best practices to be followed while writing Python, these best practices are followed so that your code does not end up having errors, easy to read and understand the code or the logic.

Python Indentation Rules

• We can’t split indentation into multiple lines using backslash.
• The first line of Python code can’t have indentation, it will throw IndentationError.
• You should avoid mixing tabs and white spaces to create indentation. It’s because text editors in Non-Unix systems behave differently and mixing them can cause wrong indentation.
• It is preferred to use white-spaces for indentation than the tab character.
• The best practice is to use 4 white-spaces for first indentation and then keep adding additional 4 white-spaces to increase the indentation.

We will have another exclusive video coming up on the topic “Python coding best practices”.

Save the above file in any folder with the name helloworld.py

.py is the file extension used to identify the file is Python script

Python Data types

In Python we have the following in-built data types.

Writing your first code in Python

by WeCanCode-Author | Jan 12, 2021 | Learn, Python

Writing your first code in Python

Today we are going to see about Writing your first code in Python

In case if you have missed our previous topics

1. Python introduction in Tamil Part 1
2. Python introduction in Tamil Part 2

Watch in youtube: https://youtu.be/Mj6HSMLvikc

Writing your first Python code

Where to write?

You can use any Notepad or Text editor for writing your Python program. But there are May IDEs available to help us with auto fill the code snippet or help us with formatting the code and check for any syntax errors.

But today we are going to write our first code, So lets use simple notepad or text editor.

Your first Python program

# This is my first Python code
# To print Hello world in the console
print("Hello World")

Save the above file in any folder with the name helloworld.py

.py is the file extension used to identify the file is Python script

Well you have now officially a Python developer, because you have written your first python code.

How to execute the Python program?

In order to execute the python program, we need Python Interpreter which will do the magic.

What is that magic?

Its the Interpretation of simple English into 0’s and 1’s, Yes the Python Interpreter is going to read your code and convert into 0’s and 1’s so that machine can understand the instructions.

To execute the Python code,

1. You need to open Terminal or Command prompt in your Machine.
2. Type “python3 filename.py” (In our case, “python3 helloworld.py”
3. Hit Enter, you should see the output in the console.