The Python isinstance() function determines the type or class of a variable. Read on to find out exactly how isinstance works, with an example below.
What are Types?
The type of a variable determines what it can or can’t do.
It determines what value the variable may take and what can be done with that value.
- OBJECT is the variable or value to check the type or class of
- CLASS is the type or class we want to see if the variable type matches
- The function returns a boolean value (True/False)
Types in Python
Generally, the type of a variable is assigned automatically when a value is assigned to it, based on the value.
It is also possible to explicitly set the type if it is different from what would be expected.
Python has several built-in types – strings, integers, and lists among them.
You can also define your own classes for your own variable structures and test against them.
Checking the Type of a Variable
The below example sets several variables, prints their type, then checks their type:
var1 = 3 var2 = "LinuxScrew!" var3= ["red", "green", "blue"] var4 = False print(type(var1)) # Will output that the type is int print(type(var2)) # Will output that the type is str print(type(var3)) # Will output that the type is list print(type(var4)) # Will output that the type is bool print(isinstance(var1, int)) # True print(isinstance(var2, bool)) # False print(isinstance(var3, list)) # True print(isinstance(var4, bool)) # True
Checking the Type of a Custom Class
Python allows you to define custom classes for your variables, which you can also check:
# Define a custom variable class which describes a car # Values given are defaults for the class class carClass: make = "Ford" model = "Falcon" var = carClass() print(isinstance(var, carClass)) # Will return True