Python Programming Basics

Python Kashmira Rao Pramod Rajan Amarjeet Sav

Introduction History Features Installation Basic Datatypes Whitespace Control Statements

Overview

http://docs.python.org/

Python is pre-installed on most Unix systems, including Linux and MAC OS X

The pre-installed version may not be the most recent one (2.6.2 and 3.1.1 as of Sept 09)

Download from http://python.org/download/ Python provides two options

IDLE Command Line Interpreter

Installing

http://python.org/download/

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Indentation matters to code meaning◦Block structure indicated by indentation

First assignment to a variable creates it◦Variable types don’t need to be declared.◦Python figures out the variable types on its own.

Assignment operator is = and comparison operator is ==

To understand the code

For numbers + , - , * , / , % are as expected

◦Special use of + for string concatenation Logical operators are words (and, or, not) not symbols

The basic printing command is print

To understand the code (cont.)

You can assign values to multiple variable at the same time >>> x, y = 2, 3>>> x2>>> y3

This makes it easy to swap values>>> x, y = y, x

Assignments can be chained>>> a = b = x = 2

Assignment

The main statement used for selecting from alternative actions based on test results

It’s the primary selection tool in Python and represents the Logic process

If Statements

Simple If statement It takes the form of an if test

if <test>: <statement>

Simple If statement if 4>3: print (“it is true that 4>3”) if a==1: print (“true” ) a=10 if a==10:

print (“a=10”)

If Statement “login” example password=‘coolguru ‘

If password== input(“Enter your password :”): print(“You have logged in” )

If... else statement It takes the form of an if test, and

ends with an optional else block

if <test>: <statement1> else: <statement2>

If Statement “login” example password=‘coolguru ‘If password== input(“Enter your password :”): print(“You have logged in” )else: print(“ invalid password “)

If… else if … else statement It takes the form of an if test, followed

by one or more optional elif tests, and ends with an optional else block

if <test1>: <statement1> elif <test2>:

<statement2> else: <statement3>

If… else if … else statement examplenumber = 23guess = int(input('Enter an integer : '))

if guess == number:print ( 'Congratulations, you guessed it.‘)print ("(but you do not win any prizes!)“)

elif guess < number:print ('No, it is a little higher than that' )

else:print ('No, it is a little lower than that‘)

Applications of python Console applications Enterprise applications Web applications Mobile applications Office applications

Applications of python contd.. Used for Scripting. Developing games. Graphics and Animation Google search engine & Youtube Yahoo maps Financial applications

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