History of Python, Advantages of Python, Applications of Python, Python Keywords, How to define an identifier, How Python differs from C, C++ and Java

2. M Vishnuvardhan
Why Python ..?
» Python works on different platforms.
» Python has a simple syntax similar to the English language.
» Python has fewer lines than some other languages.
» Python runs on an interpreter system.
» Python can be treated in a procedural way, an object-
orientated way or a functional way.

3. M Vishnuvardhan
C, C++, Java VS Python
C C++ JAVA PYTHON
Language Type Procedure Oriented Object Oriented Object Oriented
Both Procedure and
Object Oriented
Building Block Function Driven Object Driven
Both Object and
Class Driven
Function, Object and
Class driven
Extension .c .cpp .java .py
Platform Dependent Independent Independent Independent
Comment Style /* Multi Line */
//Single Line
/*Multi Line*/
//Single Line
/*Multi Line*/
#Single Line
" " " Multi-line " " "
Translator Type Compiled Compiled
Compiled &
Interpreted
Interpreted
Database Connectivity not supported not supported Supported Supported
Representing Block of
Statements
{ } { } { } Indentation
Declaring Variables Required Required Required Not Required
Applications
Compilers,
Interpreters,
Embedded
Programming etc.,
Simple desktop
applications,
Embedded Systems
etc.,
Desktop GUI, Mobile,
Web, Gaming etc.,
Desktop, Web,
Gaming, Network
Programming etc.,
Editors/ IDE Turbo C, Code Blocks
Turbo C++, Code
Blocks
Ecllipse, Netbeans
PyCharm, PyDev,
IDLE, Jupyter
Notebook, Spyder,
VS Code

4. M Vishnuvardhan
History of Python
»Python was developed by Guido van Rossum in early 90’s
@ National Research Institute for Mathematics and
Computer Science in the Netherlands.
»Python is derived from many other languages, including
ABC, Modula-3, C, C++, Algol-68, Small Talk, and Unix
shell and other scripting languages.

5. M Vishnuvardhan
History of Python
» Python released 3 major versions
» Python 1.0
» Python 2.0
» Python 3.0
» Python Timeline

6. M Vishnuvardhan
Features of Python
»Easy-to-learn.
»Easy-to-read.
»Easy-to-maintain.
»Free and Open source.
»Object Oriented.
»Large Standard library(200+)
»High level Interpreted.
»Integrated language.
»Versatile.
»Dynamically Typed
»Portable.
»Extendable.
»Databases.
»GUI Programming.

7. M Vishnuvardhan
Applications of Python

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Applications of Python
» Web & Internet Development
» Desktop GUI Applications
» Artificial Intelligence
» Machine Learning
» Image Processing
Applications
» Business Applications
» Games & 3D Graphics
» Network Programming
» Data base Access

9. M Vishnuvardhan
Top Companies using Python

10. M Vishnuvardhan
Getting Started with Python
» Python is an open source and can be download from
https://www.python.org/
» Download and install it.
» Python can be accessed in command mode or with Python
Integrated Development and Learning Environment (IDLE)
» Python programs can also be developed using Integrated
Development Environments (IDE).

11. M Vishnuvardhan
Popular Python IDE
IDE provides variety of features like
» Syntax highlighting
» error checking
» smart typing
» Multiple version support
» Debugging tools

12. M Vishnuvardhan
Python keywords
False class finally is return
None continue for lambda try
True def from nonlocal while
and del global not with
as elif if or yield
assert else import pass
break except in raise

13. M Vishnuvardhan
Identifiers in Python
Identifiers are user defined names given to classes, functions,
variables etc., Rules for creating Identifiers
» Should be Short and meaningful
» Alphanumeric both upper and lowercase (A-Z, a-z, 0-9)
» No special chars except underscore (_)
» First character must not be a digit
» It should not be a keyword
» It can be of any length
» Python is a case sensitive language

14. M Vishnuvardhan
Naming Conventions
» Class names start with an uppercase letter.
» All other identifiers start with a lowercase letter.
» Starting an identifier with a single leading underscore indicates
that the identifier is private.
» Starting an identifier with two leading underscores indicates a
strongly private identifier.
» If the identifier also ends with two trailing underscores, the
identifier is a language-defined special name.

15. M Vishnuvardhan
Blocks and Indentation
» Indentation refers to the spaces at the beginning of a code line.
» Where in other programming languages the indentation in code is for
readability only, the indentation in Python is very important.
» Python uses indentation to indicate a block of code.
» You have to use the same number of spaces in the same block of code,
otherwise Python will give you an error
Eg: if 5 > 2:
print("Five is greater than two!")
Below statement gives error
if 5 > 2:
print("Five is greater than two!")

16. M Vishnuvardhan
Python Comments
» Comments can be used to explain Python code.
» Comments can be used to make the code more readable.
» Comments can be used to prevent execution when testing code.
» Comments starts with a #, and Python will ignore them
» Using triple double quotes or triple single quotes can create a
multiline comment
Eg: #This is a comment
""" This is a comment
written in more than just one line """

17. M Vishnuvardhan
docstring
» Docstring is short for documentation string that occurs at the first
statement in a module, function, class or method definition.
Eg: def cube(num)
""" Functions used to find the cube of number"""
return (num*num*num);
Docstring can be accessed using attribute __doc__ of the function.
Eg: print(cube.__doc__)
Prints Functions used to find the cube of number

18. M Vishnuvardhan
Python variables
» Variables are containers for storing data values.
» Python has no command for declaring a variable.
» A variable is created the moment you first assign a value to it
x = 5
y = "John"
print(x)
print(y)
» Variables can change type after they have been set.
Eg: x = 5
x = "John"
print(x)

19. M Vishnuvardhan
Assignments in Python
» Values are assigned to variables using assignment operator.
Eg: x = 5
print(x)
» Python allows to assign values to multiple variables in one line
Eg: x ,y ,z = 5 ,”John” , 56.36
» Python allows to assign the same value to multiple variables.
Eg: x = y = z = 5

20. M Vishnuvardhan
Python Statements - print
» Python print() function is often used to output variables.
Eg: x = "Python is awesome"
print(x)
» In the print() function, you output multiple variables, separated
by a comma
Eg: x = "Python" y = "is" z = "awesome"
print(x, y, z)

21. M Vishnuvardhan
When we run a Python program, two steps happen
»The code gets converted to another representation called ‘Byte Code’
»‘Byte Code’ gets converted to Machine Code (which is understandable by the
computer)
Python Virtual machine – PVM

22. M Vishnuvardhan
Python Virtual machine – PVM
» The second step is being done by PVM or Python Virtual Machine. So PVM
is nothing but a software/interpreter that converts the byte code to
machine code for given operating system.
» PVM is also called Python Interpreter and this is the reason Python is
called an Interpreted language.
» We can’t see the Byte Code of the program because this happens
internally in memory.
» To get the byte code use –m D:> python -m Sample.py
» Creates a pyc file consisting Bytecode

23. M Vishnuvardhan