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Python isinstance() method

  • Last Updated : 28 Jun, 2021

Python supports object-oriented programming and hence classes can be created using python. Sometimes, it is essential to know mid-program that which objects belong to which class. isinstance() performs this function and hence makes our programming tasks easier.
 

Syntax : isinstance(obj, class)
Parameters : 
obj : The object that need to be checked as a part of class or not. 
class : class/type/tuple of class or type, against which object is needed to be checked.
Returns : True, if object belongs to the given class/type if single class is passed or any of the class/type if tuple of class/type is passed, else returns False. Raises a TypeError if anything other than mentioned valid class type. 
 

Code #1 : Demonstrating the working of isinstance for native types. 
 

Python3




# Python 3 code to demonstrate
# working of isinstance()
# with native types
 
# initializing native types
test_int = 5
test_str = "GeeksforGeeks"
test_list = [1, 2, 3]
 
# testing with isinstance
print ("Is test_int integer? : " + str(isinstance(test_int, int)))
print ("Is test_int string? : " + str(isinstance(test_int, str)))
print ("Is test_str string? : " + str(isinstance(test_str, str)))
print ("Is test_list integer? : " + str(isinstance(test_list, int)))
print ("Is test_list list? : " + str(isinstance(test_list, list)))
 
# testing with tuple
print ("Is test_int integer or list or string? : "
        + str(isinstance(test_int, (list, str, int))))
         
print ("Is test_list string or tuple? : "
        + str(isinstance(test_list, (str, tuple))))

Output: 
 

Is test_int integer? : True
Is test_int string? : False
Is test_str string? : True
Is test_list integer? : False
Is test_list list? : True
Is test_int integer or list or string? : True
Is test_list string or tuple? : False

 
Code #2 : Demonstrating use of isinstance() with objects 
 



Python3




# Python 3 code to demonstrate
# working of isinstance()
# with objects
 
# declaring classes
class gfg1 :
    a = 10
 
# inherited class
class gfg2(gfg1) :
    string = 'GeeksforGeeks'
     
     
# initializing objects
obj1 = gfg1()
obj2 = gfg2()
 
# checking instances
print ("Is obj1 instance of gfg1? : " + str(isinstance(obj1, gfg1)))
print ("Is obj2 instance of gfg2? : " + str(isinstance(obj2, gfg2)))
print ("Is obj1 instance of gfg2? : " + str(isinstance(obj1, gfg2)))
 
 
# check inhertance case
# return true
print ("Is obj2 instance of gfg1? : " + str(isinstance(obj2, gfg1)))

Output: 
 

Is obj1 instance of gfg1? : True
Is obj2 instance of gfg2? : True
Is obj1 instance of gfg2? : False
Is obj2 instance of gfg1? : True

 

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