Swapping of Two Numbers in Python – Example Code

Programming’s most fundamental yet crucial task is swapping two numbers, as computer algorithms, data structures, and other applications frequently require it. Python is an object-oriented, multipurpose language that offers several methods for switching two numbers. In this article, we will learn how to swap two numbers in Python.

What do you mean by Swapping numbers?

The value of one number can be swapped for the value of another number through number swapping. Let’s take an example where A = 10 and B = 20. If we were to do a number swap between these two values, A would become 20, and B would become 10. Applications involving various sorting algorithms, data transformations, etc., can benefit from the swapping process.

Note that there is no specific syntax or only one approach to swap two numbers. Multiple approaches are there in which there can be a usage of temporary variables, mathematical libraries, or in-built functions.

In Python, there are many methods or approaches to swapping two numbers. Mainly, there are two approaches to swapping two numbers in Python:

1. Using a Temporary (extra or 3rd) variable
2. Without using a Temporary variable

Now, we will understand these two different approaches in Python in detail, along with their subcategories with syntaxes and examples.

Using a Temporary variable

The very first approach to swap two numbers in Python is a naive or simplest or most common approach. In this approach, to swap two numbers, we will use a third variable known as the temp variable. Let’s understand this approach using a detailed example.

Syntax:

In the above syntax, we have taken three variables n1, n2, and temp. Here, the n1 and n2 represent the two numbers, whereas the temp variable is used for exchanging or swapping two numbers.

Code Example:

Output:

Explanation:

In the given example, we are swapping two numbers in Python using an extra or temporary variable. Here, we are taking inputs of two numbers from the user ‘n1’ and ‘n2’. After taking input, we store the value of ‘n1’ in the ‘temp’ variable. After that, assign the value of ‘n2’ to ‘n2’ and then, finally, assign the value stored in temp to ‘n2’.

Without using a temporary variable

To swap two numbers without using a temporary variable, we have multiple approaches. In this approach, we will not be using any temp variable for storing any one out of two numbers, instead, we will use another method like Bitwise XOR, arithmetic operations, tuple packing, etc.

Let’s see what are some methods to swap two numbers without using a temporary variable. Here is the list:

• Using arithmetic operations
• Using Bitwise XOR method
• Using comma operator
• Using list method
• Using tuple packing and unpacking

Now, let’s discuss each of them one by one in detail with code examples.

1. Using arithmetic operations (+, – or *, /)

To swap two numbers, we have a new approach that uses arithmetic operations and eliminates the usage of any third/extra/temp variable in Python programming. Let’s discuss this approach with its syntax and code examples.

Syntax:

Code Example 1:

Output:

Code Example 2:

Output:

Explanation:

In both these examples, we are simply applying arithmetic operators like +, -, *, and /, to swap the two n1 and n2 numbers.

2. Using Bitwise XOR method

To swap two numbers, we have a new approach that uses the bitwise XOR method and eliminates the usage of any third variable in Python programming. XOR bit manipulation works by returning 1 if the corresponding bits of either operand are different and 0 if they are the same. Let’s discuss this approach with its syntax and code examples.

Syntax:

Code Example:

Output:

Explanation:

In this example, we are using the bitwise manipulation using XOR, the first operation n1 = n1 ^ n2 changes n1 to the result of n1 XOR n2. For n1 = 5 and n2 = 10, n1 becomes 15 (binary: 0101 XOR 1010 = 1111). In the combined second and third operations, n2 = n1 ^ n2 changes n2 to the new n1 XOR n2, making n2 become 5 (binary: 1111 XOR 1010 = 0101). Finally, n1 = n1 ^ n2 changes to the new n1 XOR n2, making n1 become 10 (binary: 1111 XOR 0101 = 1010).

3. Using comma operator

Another approach to swap two numbers is using a comma (,) operator that eliminates the usage of any third variable in Python programming. Let’s discuss this approach with its syntax and code examples.

Syntax:

Code Example:

Output:

Explanation:

In this example, we are using the comma operator to swap n1 and n2. Here, the right side creates (packs) the tuple containing n2 and n1, and then it unpacks the n1 and n2 for swapping the two numbers.

4. Using list method

Another approach to swap two numbers is using a list in Python that eliminates the usage of any third variable. This method is like arrays in Python, but here we don’t use any external library in Python. Let’s discuss this approach with its syntax and code examples.

Syntax:

Code Example:

Output:

Explanation:

In this example, we are creating a list of n1 and n2 variables. After creating the list, we are swapping the numbers by using the index values of n1 and n2. Here, first, the n1 is at index 0, and n2 is at index 1. Now we use the comma operator here, to swap the values of n1 and n2 by assigning the n2 index to n1, and vice versa. 

5. Using functions

A very efficient approach to swap two numbers is using functions in Python that eliminate the usage of any third variable. This method is very useful and makes our code reusable, modular, etc. Here, we create a function and return the values after swapping. Let’s discuss this approach with its syntax and code examples.

Syntax:

Code Example:

Output:

Explanation:

In this example, we are creating a function swapTwoNumbers() that simply takes two input params as n1 and n2 and returns a swap of two numbers as n2, and n1.

6. Using classes and objects

Another approach to swapping two numbers is using classes and objects in Python. This method makes our code reusable, modular, and useful in cases where there are more complex behaviours. Let’s discuss this approach with its syntax and code examples.

Syntax:

Code Example:

Output:

Explanation:

In this example, we have defined a class called ‘SwapNumbers’ and initialised its two attributes as ‘n1’ and ‘n2’, where we are also creating a swapNumbers function to swap the two numbers. Finally, we create an instance ‘n’ of the class and call the ‘swapNumbers’ method in it.

Conclusion

In this article, we have learned the swapping of two numbers in the Python programming language. We have learned the different ways to swap two numbers along with their syntaxes, code examples, and outputs. Using a temporary variable is a straightforward and easier approach where we need not use any extra variable, while bitwise operators, classes, and functions provide efficient approaches to it. We have discussed various methods in this article, and now choosing the right method depends on you and your requirements. Understanding these approaches will enhance your problem-solving and also allow you to write efficient, modular, and readable code in Python language.