Computer Science

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Chapter 1 Computer Science Class XII As per CBSE Board New Syllabus 2019 20 Revision of Basics of Python Visit python mykvs in for regular updates 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 Visit python mykvs in for regular updates Features of Python 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 Visit python mykvs in for regular updates Shortcomings of Python 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 Visit python mykvs in for regular updates How to work in Python 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 Visit python mykvs in for regular updates How to work in Python Click start button All programs python version IDLE Python GUI Visit python mykvs in for regular updates How to work in Python Python command prompt Type the following at prompt print hello print 8 3 print 3 3 k 3 4 3 print k Visit python mykvs in for regular updates How to work in Python ii in Script mode Step 1 Create program file Below steps are for simple hello world program a Click Start button All Programs Python version IDLE b Now click File New in IDLE Python Shell Now type print hello print world print python is object oriented programming lang c Click File Save and then save the file with filename and py extension Visit python mykvs in for regular updates How to work in Python ii in Script mode Step 2 Run program file a b c Click Open command from IDLE s File menu and select the file you have already saved Click Run Run Module 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 Visit python mykvs in for regular updates Data Handling Most of the computer programming language support data type variables operator and expression like fundamentals Python also support these Data Types Data Type specifies which type of value a variable can store type function is used to determine a variable s type in Python Visit python mykvs in for regular updates Data type continue Data Types In Python 1 Number 2 String 3 Boolean 4 List 5 Tuple 6 Set 7 Dictionary Visit python mykvs in for regular updates Data type continue 1 Number In Python It is used to store numeric values Python has three numeric types 1 Integers 2 Floating point numbers 3 Complex numbers Visit python mykvs in for regular updates Data type continue 1 Integers Integers or int are positive or negative Integers in numbers with no decimal point Python 3 are of unlimited size e g a 100 b 100 c 1 20 print a print b print c Output 100 100 200 Visit python mykvs in for regular updates Data type continue Type Conversion of Integer int function converts any data type to integer e g a 101 string b int a converts string data type to integer c int 122 4 converts float data type to integer print b print c Run Code Output 101 122 Visit python mykvs in for regular updates Data type continue 2 Floating point numbers with a decimal point e g It is a positive or negative real numbers a 101 2 b 101 4 c 111 23 d 2 3 3 print a print b print c print d Run Code Output 101 2 101 4 111 23 6 8999999999999995 Visit python mykvs in for regular updates Data type continue Type Conversion of Floating point numbers float function converts any data type to floating point number e g a 301 4 string b float a converts string data type to floating point number c float 121 converts integer data type to floating point number print b print c Run Code Output 301 4 121 0 Visit python mykvs in for regular updates Data type continue 3 Complex numbers Complex numbers are combination of a real and imaginary part Complex numbers are in the form of X Yj where X is a real part and Y is imaginary part e g a complex 5 convert 5 to a real part val and zero imaginary part print a b complex 101 23 convert 101 with real part and 23 as imaginary part print b Run Code Output 5 0j 101 23j Visit python mykvs in for regular updates Data type continue 2 String In Python A string is a sequence of characters In python we can create string using single or double quotes Both are same in python e g str computer science print str str print string print str 0 str 0 print first char h print str 1 3 str 1 3 print string from postion 1 to 3 ell print str 3 str 3 print string staring from 3rd char llo world print str 2 str 2 print string two times print str yes str yes concatenated string Output str computer science str 0 c str 1 3 om str 3 puter science str 2 computer sciencecomputer science str yes computer scienceyes Visit python mykvs in for regular updates Data type continue Iterating through string e g str comp sc for i in str print i Output c o m p s c Visit python mykvs in for regular updates Data type continue 3 Boolean In Python It is used to store two possible values either true or false e g str comp sc boo str isupper test if string contains upper case print boo Output False Visit python mykvs in for regular updates Data type continue 4 List In Python List are collections of items and each item has its own index value 5 Tuple In Python List and tuple both are same except a list is mutable python objects and tuple is immutable Python objects Immutable Python objects mean you cannot modify the contents of a tuple once it is assigned e g of tuple tup 66 99 Tup 0 3 error message will be displayed …


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