COMPONENTS OF PYTHON PROGAM

Components of a program

Variables and assignments

Creating a variable

Creating variable was just that simply only?

In python create a variable just assign to its name the value of appropriate type.

For example – to create a variable namely student to hold student’s name and variable age to hold the student’s age, you just need to write somewhat similar to what is shown below :

student = ‘jack’

age = 16

Python will internally create labels referring to these values shown below:

student → variable for name

age → variable for age of student

some more variables –

trainno = 12345

balance=3,45,635

roll_no = 105

IMPORTANT – Variables are not storage container in python

But Python variables are not created in the form most other programming languages do.

Lvalues and Rvalues

Lvalue – values which are on the lhs (left hand side) of an assignment.

Rvalue – expressions that can come on the rhs (right hand side) of an assignment.

e.g., you can say that –

a = 20

b = 10

                                 

e.g., you cannot say that

20 = a

10 = b

The literals or the expressions that evaluate a value cannot come on lhs of an assignment hence they are rvalues but variables name come on left hand side of an assignment, they are lvalues. lvalues can come on left hand side as well as right hand side.

Multiple assignments

Python is very versatile with assignments.

Different ways of using assignments –

1 – Assigning same value to multiple variables

You can assign same values to multiple variables in a single statement,

e.g.,  a=b=c=10

 a=b=c=10

it will assign value 10 to all three variables a,b,c that is, all three labels a,b,c will refer to same location with value 10

2 – Assigning multiple values to multiple variables in a single statement,

you can even assign multiple values to multiple variable in single line

e.g., x,y,z=10,20,30

it will assign the value order wise, i.e., first variable given first value, second variable the second value and so on.

e.g., -

x,y = 25,50

print(x,y)

it will print result as –

25  50