Variable in Python

  Variable in Python

• Variable is a name of storage space which is used to store data.
• Variable value may be changed.
• Mainly variable always contains last value stored to it.
• There is no need to declare a variable in python.
• Variable is created by assigning a value to it.

Variable Initialization

name="SUNAGAR"
rollno =205
marks =85.6

• In Above example name rollno and marks are the name of variables.
• Value of name is SUNAGAR, rollno is 205 and marks is 85.6

Printing value of variable

• We can also print the value of a variable using print() function.

#creating variables
name="SUNAGAR"rollno=205
marks=85.6
#printing value of varibales
print("Name:",name)
print("Roll:",rollno)
print("Marks:",marks)
"""
***Output***
Name: SUNAGAR
Roll: 205
Marks: 85.6
"""

Assigning one value to multiple variable

• We can assign a single/one value to multiple variables using single statement in python.

#creating variables
a=b=c=90
#printing value of varibales
print("a:",a)
print("b:",b)
print("c:",c)
"""
***Output***
a: 90
b: 90
c: 90
"""

Assigning multiple values to multiple variables

• We can also assign multiple values to multiple variables using single statement in python.

#creating variables
a,b,c=70,80,90
#printing value of varibales
print("a:",a)
print("b:",b)
print("c:",c)
"""
***Output***
a: 70
b: 80
c: 90
"""

Rules to define a variable

• 1st letter of a variable should be alphabet or underscore(_).
• 1st letter of variable should not be digit.
• After 1st character it may be combination of alphabets and digits.
• Empty spaces are not allowed in variable name.
• Variable name must not be a keyword.
• Variable names are case sensitive for example marks and MARKS are different variables.

Local Variable

• A variable declared within the body of the operate is named native/local variable.
• Local variable may be used only within that operate during which it's defined.

#function definition
def add():
    #creating variable
    x=50
    y=30
    z=x+y
    print("Add=",z)
#Calling funtion
add()
#This line will raise an error
#because x is local variable
#and it can't be accessed
#outside function
print(x)
"""
***Output***
Add= 80
NameError: name 'x' is not defined
"""

Global Variable

• variable which is defined outside a function is called global variable.
• Global variable can be used anywhere in the program.

#creating global variable
x=50
y=30
def add():
    #accessing global variable
    #inside a function
    print("Inside function Sum=",x+y)
#Calling funtion
add()
#accessing global variable
#outside a function
print("Outside function Sum=",x+y)
"""
***Output***
Inside function Sum= 80
Outside function Sum= 80
"""
 

Local and Global variable with same name

#creating global variable
x=50
def add():
    x=20
    # this line will print 20
    print("Inside function x=",x)
#Calling funtion
add()
#this line will print 50
print("Outside function x=",x)
"""
***Output***
Inside function x= 20
Outside function x= 50
"""