TUTORIAL: Pass A Variable Num. of Args to a Python Function

Introduction

Note: Trying to do this in PHP? Check this out.

When declaring a function, the type and number of arguments are usually fixed at compile time. But sometimes it is necessary for a function to be able to accept a variable number of arguments unknown until run-time.

This tutorial will show you how to create a Python function that can accept a variable number of arguments.

In A Nutshell

If you're simply looking for an example to go off of, I won't keep you waiting. Here's an example of a function sum() that adds up all of the integers passed to it and returns the sum:

How It Works

Let's look at the code line by line:


We declare our function. When this function is called, a tuple will be created from the arguments passed to the function, and this tuple will be stored in the variable args.


Here we simply create a local variable to hold our return value as we add the individual integers to it.


Here we loop through the list of arguments and add their values to the total. Since tuples are iterable with a simple for-loop, no extra work is needed.


Finally, we return our total.

A Handy Tool: Create A List

One special thing to note is that because the arguments are stored in an immutable tuple, we can convert this tuple to a list using the list() constructor:



In doing so, we are now able to use list methods such as pop() on our arguments, and we can eliminate the temporary iteration variable i:

Conclusion

You should now know how to create a Python function that accepts a variable number of arguments at run-time.

I always welcome questions or feedback about this tutorial. Simply post a reply or PM me; I'm glad to help!