Python Integer: Explained With Example Code

The Python integer is a non-fractional number, like 1, 2, 45, -1, -2, and -100. It’s one of the three types of numbers Python supports natively, the others being floating-point numbers and complex numbers.

Max size of a Python integer

Unlike many other programming languages, integers in Python 3 can have large values. In fact, they are unbounded, meaning there is no limit to their size, for example:

>>> num = 98762345098709872345000
>>> num + 1

Of course, there is a limit, since your computer does not have unlimited memory. However, for all practical purposes, you don’t have to worry about it.

Integer types

Unlike Python 2 and many other languages, Python 3 has only one type of integer. This is part of Python’s aspiration to be a clean, easy to learn language. It’s one less thing we have to worry about. For more details, see PEP-0237.

Converting from and to an integer

String to integer

To convert a string to integer in Python, use the int() function:

>>> int('100')

Integer to string

To convert an integer to a string in Python, use the str() function:

>>> str(200)

Float to integer

To convert a float to an integer, use the int() function:

>>> int(2.3)

Python random integer

Many use cases require a random integer. For this, you need to import the module random. Be warned that this offers pseudo-randomness, which is not suitable for cryptography.

Let’s get a random number:

>>> import random
>>> random.randint(1,10)

The above instruction returns a pseudo-random number from 1 to 10 inclusive, which means including 1 and 10. For full details of the random module, visit the Python documentation.

Is it a Python integer?

To check if a value is an integer, we can use the type() function. It will return int for integers. Here’s a simple example of how to use this in an if-statement:

>>> type(2)
>>> if isinstance(2, int):
...     print('An integer')
An integer

Don’t use if type(2) == int.
Using isinstance() is almost always the better, cleaner way and covers more use cases, like subclasses.

About Erik van Baaren

Erik is the owner of Python Land and the author of many of the articles and tutorials on this website. He's been working as a professional software developer for 25 years, and he holds a Master of Science degree in computer science. His favorite language of choice: Python! Writing good articles takes time and effort. Did you like this tutorial? You can buy him a coffee to show your appreciation.

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