Python isinstance() Function

The isinstance() function in Python is used when we need to check whether a particular object is an instance of specified type or not. For example:

x = 100
if isinstance(x, int):
    print("The object 'x' is an instance of 'int'")
else:
    print("The object 'x' is not an instance of 'int'")

Because the value initialized to x is 100, which is an int type value. Therefore the output will be:

The object 'x' is an instance of 'int'

Note - When a new context (for example: an object) is created based on previously created model (for example: a class), it can be said that the model has been instantiated. Two instances of same model or type have same data structure.

Python isinstance() Function Syntax

The syntax of isinstance() function in Python, is:

isinstance(obj, type)

where obj is an object, whereas type refers to type like int, float etc., or a class, or tuple of types and/or class(s)

Note - The isinstance() returns True, if specified object (obj) is of specified type. Otherwise returns False

Python isinstance() Function Example

Here is an example of isinstance() function in Python.

x = "Python Programming"
myTypes = (int, float, str)

if isinstance(x, myTypes):
    print("The object 'x' is an instance of any type in 'myTypes' Tuple")
else:
    print("The object 'x' is not an instance of any type in 'myTypes' Tuple")

The output will be:

The object 'x' is an instance of any type in 'myTypes' Tuple

This is because, when the type parameter is a tuple, means isinstance() returns True, if the specified object is one of the type in specified tuple.

I've created another program that demonstrates the use of isinstance() function in Python, to check whether an object is an instance of any particular user-defined class or not:

class CodesCracker:
    Name = "Dominic"
    Course = "EECS"

x = CodesCracker()
print(isinstance(x, CodesCracker))

Because the object x is/becomes an instance of the class CodesCracker using the following statement:

x = CodesCracker()

Therefore the output produced by above program, will be:

True

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