Python Basics

In this tutorial, we will learn about the basics of Python, a very famous programming language. This tutorial will help you understand the language better if you start with python. Let’s know more about python through these given points.

What is Python?

• Python was created by Guido van Rossum during 1985- 1990.
• Python is a general-purpose language that can be used to create all kinds of programs.
• Python is an object-oriented programming language.
• Python is an interpreted language, meaning that the source code is converted into the byte code and then executed by the machine.
• Python is versatile and easy to learn, making it one of the most used languages for application development.
• Python provides multi-programming patterns that support object-oriented, imperative, procedural and high-level programming.

Why learn Python?

• It is a beginner’s language.
• It is easy to learn and maintain.
• It provides readability.
• It is interactive.
• It provides dynamic data types.
• It works on different platforms like Windows, Linux, Mac, etc.
• It has a very simple syntax very similar to the English language.
• It allows the developer to write a code in fewer lines.
• It provides dynamic memory location.

What is Python used for?

• Used for creating web development.
• Used for creating software development.
• Used for connecting to the database system.
• Used for working with big data.
• Used for developing both online as well as offline applications.

Prerequisite

Before starting a programming language, you should know about computers and their basics. It’s good to have a basic knowledge of programming language. Still, even if you have no prior knowledge about any other programming language, you can learn Python as the first-ever programming language.

Python Syntax

In many other programming languages like C, C++, and Java, we used semi-colon (;) to separate two lines. Instead of a semi-colon, we use indentation and while space in python. We don’t even have to use curly braces for starting and ending a function.

For example-

def function_name ( ):
              1st statement
              2nd statement
              3rd statement
               ………………....
             Nth statement

Note: We mostly use four whitespaces to provide indentation in Python.

Python Indentation

Indentations are the spaces left blank before a line of code. It is a very important and unique concept of python. Indentations are used to show a block of code. Python will throw an error if we don’t use indentation, known as an indentation error.

Example1

if (4 < 9):
      print(“Welcome to Tutorial And Example”)

Output

Welcome to Tutorial And Example

Example2

if( 4 < 9 ):
print(“Welcome to Tutorial And Example”)

Output

print(“Welcome to Tutorial and Example”)
              ^
IndentationError: expected an indented block.

Explanation     

In the above two examples, one is a valid code with proper indentation, and the other is an invalid code that will give an indentation error. Example1 will print the value Welcome to Tutorial And Example, whereas example2 will throw an IndentationError.

Python Comments

In python, any line that starts with # is treated as a comment. Comments are used to describe the code. Whenever we write a program, we often use comments to explain it. Comments are not treated as part of a code and are ignored by the machine while executing the code.

We can have a single-line comment and a multi-line comment, but in both cases, we have to use hash (#) at the beginning of the code. Comments are mainly used to increase the readability of the code.

Example

# This is a single-line comment
print (“Welcome to Tutorials And Example”)
# This is a
# multi-line comment 
 print (“Welcome again!”) 

Output

Welcome to Tutorials And Example
Welcome again!

Another way to comment in python is by using triple quotes in your code. Whatever is written inside the triple quotes (also known as multiline string) is treated as a comment in the python programming language.

Example

“““ This is another way of 
Commenting in Python 
”””
print (“Welcome to Tutorials And Example”)

Output

Welcome to Tutorials And Example

Python Keywords

We often use products in our life which are reserved or meant to do one particular thing, and we cannot use them to do any other task. Similarly, keywords are those special words meant to perform only one task. They are reserved for special purposes. We cannot use keywords for naming a variable or function.

There are 33 keywords in Python.

await              None           break          except       in                   raise                 async

import            and              continue    for             lambda          try                      if

pass                 as                def               from         nonlocal         while                 or

else                 True            class            finally        is                    return               elif

import            assert        del                 global      not             with       yield

Note: Keywords are case sensitive, except for three; all other keywords are lowercase.

Input & Output Function

In python, we should know how to take inputs from a user and be able to print that outputs. To take inputs from the user, we use the input( ) function. To print the given input from a user, we use the print( ) function.

Example

# This is how we take inputs
age = input( “Enter your age: ” )


# Let the entered age be 22
print( “Your age is ”, age )

Output

Enter your age: Your age is 22

Python Data Types

Data types are one of the most important topics to understand while preparing for job interviews. Not just in python, data types are the core concept of any programming language. It’s very important to understand it well to write a very efficient program.

Data type represents the type of value stored in the variable. It is the most fundamental concept of any programming language. Let’s understand these built-in data structures in python.

• Numeric Types:  Int, float, complex.
• Text Types:  str.
• Sequence Types:  list, tuple, range.
• Set Type: set, frozenset.
• Mapping Types: dict.
• Binary Types: bytes, memoryview, bytearray.
• Boolean Types: bool.
• None Types: None.

Let’s understand these data types with better examples.

# This is an integer
x = 20
# This is a float value
x = 2.5
# This is complex value
 x = 4j
# This is string type
x = “TutorialAndExample”
# This is list type
x = [33, 44, 55]
# This is tuple type
x = ( 33, 44, 55) 
# This is range type
x = range(10) 
# This is set type
x = {“Apple”, “Banana”, “Grapes”}
# This is frozenset type
x = frozenset( {“Apple”, “Banana”, “Grapes”})
# This is Boolean type
x = True 
# This is byte type
x = b“Hello” 
# This is bytearray type
x = bytearray(10)
# This is memoryview type
x = memoryview(byte(10))
# This is None Type
x = None 

We can specify the data type using a constructor function. Let’s understand with an example.

# This is how we specify a data type
x = float(20) 
print(x)

Output

20.0

Explanation

We have specified an integer value as a float value using a constructor function in the above code. We can do this with all types of compatible data types.

Python Variables

Variables are one of the most important terms we should be familiar with if we want to be good programmers. In simpler words, we use variables to store a value. We can think of variables as a name given to a container used to store a value, and they can be changed anytime during the program's execution.

The syntax for creating variables in Python

variable_name = value

Rules of Creating Variable

• A variable name can only contain alpha-numeric characters (A-z, 0-9) and underscore ( _ ).
• We cannot start a variable name with a number. For example, 12a is an invalid variable.
• A variable name can start with an underscore. For example, _x is a valid variable.
• A variable name can start with a letter. For example, age can be a variable name.

Valid Variable Names

• first_var
• firstvar
• _first_var
• firstVar
• FIRSTVAR

Invalid Variable Names

• 1stvar
• first-var
• first var

Example

#declaring the variables
a = 9        #a is of type integer
b = 10.5             #b is of type float
c = “TutorialAndExample”       #c is of type string


#displaying the variables
print(a)
print(b)
print(c)

Outputs

9
10.5
TutorialAndExample

Python Function

Functions are a set of well-defined code which only works when it is called. Functions are defined and called to perform a specific task/operation.

In python, a function is defined using the def keyword; inside it, we can pass data as arguments. It also returns data as a result. We can also pass information in the form of an argument.

In python, parameters and argument are the same thing and can be used in place of each other. Parameters are the value inside the parentheses, whereas arguments are the value passes on.

The function should be called with the correct number of arguments. Otherwise, it will throw an error.

Example

def fun( ):
     print(“Hi! Welcome to TutorialAndExamples”)


fun()

Output

Hi! Welcome to TutorialAndExamples

Explanation

In the above code, a function is defined using the def keyword and function name as fun(). It is called using the same function name fun() in the last line.

Conclusion

This tutorial has covered almost all the basic concepts you should know before starting with the python programming language. There are so many things that come under python. It is very useful in real-world applications. These days Python are used everywhere. Hopefully, you will get a basic understanding to start your hands-on practice with python.