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Informatics Practices

Class XI ( As per CBSE Board)

Chapter 4 Getting Started With python

New syllabus 2020-21

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Python Introduction

It is widely used general purpose,high level programming language.Developed by Guido van Rossum in 1991.

It is used for:

software development,

web development (server-side), system scripting,

Mathematics.

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Features of Python

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  1. Easy to use – Due to simple syntax rule
  2. Interpreted language – Code execution & interpretation line by line
  3. Cross-platform language – It can run on windows,linux,macinetosh etc. equally
  4. Expressive language – Less code to be written as it itself express the purpose of the code.
  5. Completeness – Support wide rage of library
  6. Free & Open Source – Can be downloaded freely and source code can be modify for improvement

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Shortcomings of Python

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  1. Lesser libraries – as compared to other programming languages like c++,java,.net
  2. Slow language – as it is interpreted languages,it executes the program slowly.
  3. Weak on Type-binding – It not pin point on use of a single variable for different data type.

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Installing Python

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Two Steps Only –

​

  1. Download Python distribution
  2. Python installation process

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Installing Python

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1. Download Python distribution

You can download python distribution from the link given below https://www.python.org/downloads/

Note – Download only that python distribution/MSI Installer, which is best suited for

the Operating system on which you want to install it.

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Installing Python

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2. Python installation process

1. Double-click the icon labeling the file <version>.exe Popup window will appear

Click on Run option

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Installing Python

2. Setup popup window will appear

If the Python Installer finds an earlier version of Python installed on your computer, the Install Now message will instead appear as Upgrade Now(and the checkboxes will not appear).

Highlight the IVnistital:l pNyotwho(no.rmUypkgvsra.idnefoNrorweg)umlaersusapgdea,taens d then click it

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Installing Python

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3. User Account Conrol pop-up window will appear

Click the Yes button.

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Installing Python

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4. A new Python <version> Setup pop-up window will appear

with a Setup Progress message and a progress bar.

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Installing Python

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5. Soon, a new Python <version> Setup pop-up window will appear with a Setup was successfully message

Click the close button

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How to work in Python

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After installation of python ,we can work on it in following ways

  1. in Interactive mode
  2. in Script mode

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How to work in Python

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(i) in Interactive mode

* Search the python.exe file in the drive in which it is installed.

If found double click it to start python in interactive

mode

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How to work in Python

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* Click start button -> All programs -> python<version>->IDLE(Python GUI)

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How to work in Python

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Python command prompt >>>

Type the following at prompt

print “hello”

print 8*3 print 3**3 k=3+4*3

print k

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How to work in Python

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(ii) in Script mode

Step 1 (Create program file)

Below steps are for simple hello world program

  1. Click Start button->All Programs ->

Python<version>->IDLE

  1. Now click File->New in IDLE Python Shell Now type

print “hello” print “world”

print “python is”,”object oriented programming lang.”

  1. Click File->Save and then save the file with filename and .py extension

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How to work in Python

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(ii) in Script mode

Step 2 (Run program file)

  1. Click Open command from IDLE’s File menu and select the file you have already saved
  2. Click Run-> Run Module
  3. It will execute all the commands of program file and display

output in separate python shell window

Note :- Python comes in 2 flavours – python 2.x and python 3.x . Later one is Backward incompatible language as decide by Python Software foundation(PSF). Mean code written in 2.x will not execute on 3.x . Visit the below link for difference between 2.x & 3.x

https://www.geeksforgeeks.org/important-differences-

between-python-2-x-and-python-3-x-with-examples/