Python isinstance（）

The isinstance() function checks if the object (first argument) is an instance or subclass of classinfo class (second argument).

The syntax of isinstance() is:

isinstance(object, classinfo)

　　

isinstance() Parameters

 The isinstance() takes two parameters:

• object - object to be checked
• classinfo - class, type, or tuple of classes and types

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Return Value from isinstance()

The isinstance() returns:

• True if the object is an instance or subclass of a class, or any element of the tuple
• False otherwise

If classinfo is not a type or tuple of types, a TypeError exception is raised.

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Example 1: How isinstance() works?

class Foo:
  a = 5
  
fooInstance = Foo()

print(isinstance(fooInstance, Foo))
print(isinstance(fooInstance, (list, tuple)))
print(isinstance(fooInstance, (list, tuple, Foo)))


When you run the program, the output will be:

True
False
True

　　

Example 2: Working of isinstance() with Native Types

numbers = [1, 2, 3]

result = isinstance(numbers, list)
print(numbers,'instance of list?', result)

result = isinstance(numbers, dict)
print(numbers,'instance of dict?', result)

result = isinstance(numbers, (dict, list))
print(numbers,'instance of dict or list?', result)

number = 5

result = isinstance(number, list)
print(number,'instance of list?', result)

result = isinstance(number, int)
print(number,'instance of int?', result)


When you run the program, the output will be:

[1, 2, 3] instance of list? True
[1, 2, 3] instance of dict? False
[1, 2, 3] instance of dict or list? True
5 instance of list? False
5 instance of int? True