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Name derived from famous BBC comedy show namely Monty Python’s flying circus

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  • Python was created by Guido Van Rossum
  • The language was released in February I991
  • Python got its name from a BBC comedy series from seventies- “Monty Python‟s Flying Circus”
  • Python can be used to follow both Procedural approach and Object Oriented approach of programming
  • It is free to use
  • Python is based on or influenced with two programming languages:
    • ABC language [replacement of BASIC]
    • Modula-3

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  • Easy to use Object oriented language
  • Expressive language
  • Interpreted Language
  • Its completeness
  • Cross-platform Language
  • Fee and Open source
  • Variety of Usage / Applications

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  • Python is compact and very easy to use object oriented language with very simple syntax rules. It is very high level language and thus very-very programmer -friendly
  • More capable to express code‟s purpose than many othr language like – swapping of two numbers:

In C++

In Python

int a=2, b=3, tmp;

a,b=2,3

tmp=a;

a,b=b,a

a=b;

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b=tmp;

VINOD KUMAR VER

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MA, PGT(CS), KV OEF KANPUR &

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  • It is interpreted not compiled, thus executes code line by line and it makes python easy-to-debug and suitable for beginners and advanced users
  • When you install Python, you get everything i.e. you don‟t need to install additional libraries. All functionality is available with Python additional library. Features like web-pages, database connectivity, GUI features are available in Python standard library. Python follows – “Battery included” philosophy

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  • Python can run equally well on variety of platforms – Windows, Linux/UNIX, Macintosh, supercomputers, smart phones. Python is portable language.
  • It is feely available i.e. without any cost can be downloaded from www.python.org.
  • It is also open source i.e. you can modify, improve/extend an open-source software

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  • Python is being used in many diverse fields/applications, some of which are:
    • Scripting
    • Web Applications
    • Game Development
    • System Administrations
    • Rapid Prototyping
    • GUI Programs
    • Database Applications

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  • Not the fastest language
  • Lesser Libraries than C, Java, Perl
  • Not Strong on Type-binding
  • Not Easily convertible

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  • Because of its interpreted nature Python is not fast as compare to compiled language. Python is first compiled into an internal byte-code which is then executed by Python interpreter.
  • Python offers library support for almost all computing programs, but its library is still not competent with languages like C, java as they have larger collection available.

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  • Python is not very strong on data type checking i.e. “Type- mismatch” issues. For example if you declare variable as integer but later store a string value in it, Python will not raise any error.
  • Because of its lack of syntax, Python is easy to program but it becomes disadvantage when it comes to translate python program to another language.

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Before we start working on Python we need to install Python in our computer. There are multiple distributions available today:

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  • Default Installation available from www.python.org is called Cpython installation and comes with python interpreter, Python IDLE(Python GUI) and Pip(package installer)
  • ANACONDA Python distribution is one such highly recommended distribution that comes with preloaded many packages and libraries(NumPy, SciPy, Panda etc)
  • Other Popular IDEs like Sypder, PytCharm, etc. Spyder IDE is

available as a part of ANACONDA.

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After Python installation we can start working with python. In Python we can work in 2 ways:

Python working Ways

Interactive Mode

(Immediate Mode)

Script Mode

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The default installation of CPython comes with Python

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Interpreter, Python IDLE and pip(package installer). To work in either interactive mode or script we need to open Python IDLE

To work in interactive mode, follow the process given below:

(i) Click start button 🡪 All Programs 🡪 Python 3.6.x 🡪IDLE Or

Click start button 🡪 All Programs 🡪 Python 3.6.x 🡪Python

(command line)

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  • Interactive modes – one command at a time
  • Python executes the given command and gives the output.
  • In interactive mode we type command at IDLE prompt ( >>> )
  • For e.g if you type 20 + 30 in from of IDLE prompt

>>> 20 + 30

50

(command give by user)

(output given by python)

  • From the above example you can see than at >>> we have to just give the command to execute and python we execute it if it is error free otherwise gives an error.

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)

( )

( )

(

(

)

( )

print (“Hello”)

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  • Script Mode – multiple commands can be saved in a file as a

program and then we can execute the entire program

  • we type Python program in a file and then use the interpreter to execute the content from the file.
  • Working in interactive mode is convenient for beginners and for testing small pieces of code, as we can test them immediately. But for coding more than few lines, we should always save our code so that we may modify and reuse the code

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  • In Python IDLE :
    • Click File 🡪 New
  • In new window type the commands you want to save in program
  • For example:
    • print(“Hello World!”)
  • File🡪Save to save file. Give extension .py to execute it as python script

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Save the program and press F5

(

)

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Type the below code in script file:

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#My First Program print(“Hello World!”)

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When you execute the script file output will be only Hello World

Note: the first line starts from # which makes line as a comment i.e. only for programmer information not for interpreter. Comments are ignored by interpreter

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To print or display output Python 3.x provides print() function. Examples:-

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print(“Welcome to Python”)

it will print Welcome to Python

print(„Python rocks!‟)

it will print Python rocks!

Note: Python allows both single quotation and double quotation to enclose string. In any case both opening and closing must be same.

print(„Look carefully”)

it will give error because both opening and closing quotes are different.

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Note:

  1. In Python 2.x print is a statement, not a function
  2. Python is case-sensitive i.e. it will treat small letter and capital letter as two different entities like m & M will be treated differently in Python.
  3. We can use up arrow (↑) and down arrow (↓) to select previous command and press enter to recall and execute.
  4. print statement is required only while working with script mode otherwise in interactive mode values can be printed without print statement

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  • Who developed Python Programming Language?
  • Is Python Object Oriented Language?
  • Python is a high level interpreted language. What does it means
  • What does cross-platform means?
  • Python is free and open source. What do you understand by this feature?
  • What is the difference in interactive mode and Script mode in Python?

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