How to Swap Two Variables Without Using a Third Variable in Python

Swapping the values of two variables is one of the first tricks you learn when starting to code. Usually, this involves using a temporary third variable to hold one of the values during the swap. But did you know that you can swap two variables in Python without using a third variable?

In this post, I’ll show you a simple, elegant way to do this using Python’s tuple unpacking feature. Let’s get started!

The Traditional Method: Using a Temporary Variable

Typically, when swapping two variables, you might write code like this:

# Swapping using a third variable
a = 5
b = 10

temp = a
a = b
b = temp

print(f"After swapping: a = {a}, b = {b}")

Here, we use a temporary variable (temp) to hold the value of a while assigning the value of b to a. Finally, the temporary variable (temp) is assigned to b. This works, but it can be a bit clunky.

The Pythonic Way: Swapping Without a Third Variable

In Python, you can swap two variables without needing a temporary variable. This is made possible by tuple unpacking, a powerful feature that allows you to assign multiple values at once. Here’s how you can swap two variables in just one line of code:

# Swapping without using a third variable
a = 5
b = 10

a, b = b, a

print(f"After swapping: a = {a}, b = {b}")

Output:

After swapping: a = 10, b = 5

How Does It Work?

In the above example, a, b = b, a is a tuple unpacking operation. Here’s a breakdown of how it works:

On the right-hand side of the assignment (b, a), Python creates a tuple containing the values of b and a.
On the left-hand side (a, b), Python unpacks this tuple and assigns the first value to a and the second value to b.
This all happens in one step, so there’s no need for a temporary variable.

Advantages of Tuple Unpacking

Simplicity: You can swap two variables in a single line of code.
Readability: The syntax is clean and easy to understand, especially for those familiar with Python.
No Temporary Variables: You save memory and improve efficiency by not using extra variables.

Real-World Use Cases

Swapping variables without a temporary one can be particularly useful in competitive programming and scenarios where minimizing code is essential. This approach is also popular in data manipulation tasks, where you may need to swap rows, columns, or values quickly.

Conclusion

Swapping two variables without a third variable is a quick, efficient trick in Python thanks to tuple unpacking. It’s not only cleaner but also a great way to write concise and readable code.

Try implementing this in your next Python project and see how it simplifies your code!