Variables In Python

  • – Variables are used in every programming language and their importance in programming cannot be over-emphasized.
  • – Variables in python programming can be considered as a storehouse for data or values.
  • – In other words, variables are containers where values are stored.
  • – Variables can be used with strings, numbers and integers.
  • – In Python, you do not need to specify the type of value in your variable
  • – Python is able to detect whether the value you are trying to assign to a variable is a number, integer or a string.

How Many Type Of Variable Are There In Python

    		   		Variable
1) Procedural/Functional oriented	2) Object Oriented
   a) Local			            a) Local
   b) Global		                    b) Global
				            c) Class level[Static]
			                    d) Object level[Instance]

Procedural/Functional Oriented- Local And Global Variable-

Ex-

x = 70  # Global variable
class Demo:
    x = 30  # Class variable

    def display1():
        x = 10  # Local variable
        print(x)  # 10
        print(Demo.x)  # 30

    def display2():
        print(x)  # 70
        print(Demo.x)  # 30

    def main():
        Demo.display1()
        Demo.display2()

Demo.main()

Output-
10
30
70
30

Object Oriented- Local, Global And Class Level Variable-

x=70 #Global variable
class Demo:
    x=30 #Class level Variable
    def display1():
        x=40 #Local variable
        print(x) #40
        print(Demo.x) #30

    def display2():
        print(x)  #70
        print(Demo.x)   #30

    def main():
        Demo.display1()
        Demo.display2()

Demo.main()

Output-
40
30
70
30

Object Level Variable-

class Demo:
    def display1(): #Class level method
        print("Inside display1")

    def display2(self): #Object level method
        print("Inside display2")

    def main():
        Demo.display1()
        obj = Demo() #Demo() --> Will Return the address of the object.. Ex- Returning the address as 2048
        # ar --> Referenced variable which will hold the address of the Demo() object.
        obj.display2()

Demo.main()

Output-
Inside display1
Inside display2

Global Keyword-

  • – This keyword is used to set the global variable from inside the function.
  • – global keyword should always be placed at 1st statements inside the function.
x = 20
def display1():
    global x
    print(x)  # 20
    x = x + 10 
    print(x) # 30

def display2():
    print(x)  # 30
    # x = x + 20  # 40  #UnboundLocalError: local variable 'x' referenced before assignment

display1()
display2()

Output-
	20
	30
	30  

Ex-
def display():
    global x
    x = 70

display()
print(x)  # 70

Output-
70

Ex-
x=40
def display():
    x=10
    print(x) #40
    global x # SyntaxError: name 'x' is used to global declaration
    print(x) #
display()
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