Python Check If A Variable Is An Integer

In this Python tutorial, we will discuss how to check if a variable is an integer in Python. We will also discuss, how to check if a number is an integer in Python.

Table of Contents

Python check if a variable is an integer

To check if the variable is an integer in Python, we will use isinstance() which will return a boolean value whether a variable is of type integer or not.

Example:

my_variable = 56
print(isinstance(my_variable, int))

After writing the above code (python check if the variable is an integer), Ones you will print ” isinstance() “ then the output will appear as a “ True ”. Here, isinstance() will check if a variable is an integer or not and if it is an integer then it will return true otherwise false.

You can refer to the below screenshot to check if the variable is an integer.

This is how to check if a variable is an integer in Python.

Let us explore, different methods to check if a variable is an integer in Python.

How to check if a variable is an integer in Python

1. Using isinstance()

The isinstance() function in Python is a built-in function that checks if a variable is an instance of a specific class or a subclass thereof. Here’s how we can use isinstance() to check if a variable is an integer:

def is_integer(n):
    return isinstance(n, int)

print(is_integer(5))  # Outputs: True
print(is_integer(5.5))  # Outputs: False
print(is_integer("5"))  # Outputs: False

In this example, is_integer() returns True when the variable is an integer and False otherwise. You can see the output like below:

check if a variable is an integer in python

2. Using type()

While isinstance() checks if a variable is an instance of a specific class or a subclass thereof, the type() function strictly checks if a variable is an instance of a specific class and not its subclasses. Here’s how to use type() to check if a variable is an integer:

def is_integer(n):
    return type(n) is int

print(is_integer(5))  # Outputs: True
print(is_integer(5.5))  # Outputs: False
print(is_integer("5"))  # Outputs: False

Once you execute the code, you can see the output:

3. Using the math module

We can also use the Python math module to check if a number is an integer. This method works well when we want to check if a floating-point number is, in fact, an integer.

import math

def is_integer(n):
    if isinstance(n, float):
        return n.is_integer()
    elif isinstance(n, int):
        return True
    else:
        return False

print(is_integer(5))  # Outputs: True
print(is_integer(5.0))  # Outputs: True
print(is_integer(5.5))  # Outputs: False
print(is_integer("5"))  # Outputs: False

4. Exception handling

Sometimes, we might want to check if a variable can be converted to an integer, even if it’s not already one. This can be useful when reading data from files or user input. We can use a try/except block to do this:

def is_integer(n):
    try:
        int(n)
        return True
    except ValueError:
        return False

print(is_integer(5))  # Outputs: True
print(is_integer(5.5))  # Outputs: True
print(is_integer("5"))  # Outputs: True
print(is_integer("5.5"))  # Outputs: False

5. Checking if a float is a whole number

If you’re dealing with floats and want to check if they could be an integer (i.e., they are a whole number), you can use the is_integer() method available on all float instances:

def is_integer(n):
    return isinstance(n, float) and n.is_integer()

print(is_integer(5.0))  # Outputs: True
print(is_integer(5.5))

How to check if a number is an integer in Python

In Python you can check if a number is an integer by using the isinstance() built-in function. The isinstance() function checks if the object (first argument) is an instance or subclass of classinfo class (second argument).

Here is a simple Python function that checks if a number is an integer:

def is_integer(n):
    if isinstance(n, int):
        return True
    else:
        return False

You can then use this function to check various numbers like so:

print(is_integer(10))     # prints: True
print(is_integer(10.0))   # prints: False
print(is_integer('10'))   # prints: False

The function is_integer checks whether the input n is an integer.

If the input n is an integer, isinstance(n, int) is True and the function returns True.
If the input n is not an integer, isinstance(n, int) is False and the function returns False.

The print statements then print the output of the function for different inputs.

It’s important to note that is_integer() will return False for floating point numbers even if they represent a number that could be an integer (like 10.0). If you would like it to return True for those cases, you would need to write your function slightly differently:

def is_integer(n):
    if isinstance(n, int):
        return True
    elif isinstance(n, float) and n.is_integer():
        return True
    else:
        return False

And you can use them like below:

print(is_integer(10))     # prints: True
print(is_integer(10.0))   # prints: True
print(is_integer(10.5))   # prints: False
print(is_integer('10'))   # prints: False

In this second version of the function, is_integer() checks additionally if n is a float and if it represents an integer number. If both conditions are true, it returns True.

This is how to check if a variable is an integer in Python.

Conclusion

In this tutorial, we have learned, how to check if a number is an integer in Python and also how to check if a variable is an integer in Python.