Swapping Of Two Numbers in Python Programming

There are several ways to swap two numbers in python coding(variable value), from traditional methods used in other languages to Pythonic one-liners.

In this post, you'll learn:

• What it means to swap two numbers
• Different methods to perform the swap
• The Pythonic way (and why it’s awesome)

Swapping Of Two Numbers in Python Programming

Getting Started

Swapping two numbers means exchanging their values. For example:

 a = 5  
 b = 10  

After swapping:

 a = 10  
 b = 5  

Swapping of two numbers in python is one of the most basic programming exercises and a great way to understand variable manipulation. Now, let’s see how this can be achieved in Python.

Swap Two Numbers in Python Using a Temporary Variable

Using a temporary variable, swapping of two numbers in Python is a simple and clear method. Here's how you can do it:

Example:

 # Input values  
 a = 5  
 b = 10  
 print("Before swapping:")  
 print("a =", a)  
 print("b =", b)  
 # Swapping using a temporary variable  
 temp = a  
 a = b  
 b = temp  
 print("\nAfter swapping:")  
 print("a =", a)  
 print("b =", b)  

Output:

 Before swapping:  
 a = 5  
 b = 10  
 After swapping:  
 a = 10  
 b = 5  

Swapping two numbers using a temporary variable is easy to understand and works in all programming languages, but it requires extra memory for the temporary variable. The method below swaps two numbers without using a third variable by performing arithmetic operations, thereby avoiding the use of extra memory.

Swap Without Third Variable

Swapping two variables without using a third (temporary) variable in Python can be done in several ways. Here are the most common ones:

Using Arithmetic Operations

Example:

 a = 5  
 b = 10  
 # Swapping  
 a = a + b # a = 15  
 b = a - b # b = 5  
 a = a - b # a = 10  
 print("a =", a)  
 print("b =", b)  

Problem: Be cautious with large integers, as they can cause overflow in some programming languages (though this is not usually an issue in Python due to its support for arbitrary-precision integers). To avoid overflow, a clear alternative method is using Bitwise XOR.

Using Bitwise XOR

 a = 5  
 b = 10  
 a = a ^ b  
 b = a ^ b  
 a = a ^ b  
 print(a, b) # Output: 10 5  

Problem: This method only works for integers and is a bit more obscure, so it’s less commonly used in practice. To overcome this Python provides a clean and elegant way to swap values using tuple unpacking

Pythonic Way (Tuple Unpacking)

 a = 5  
 b = 10  
 # Swapping  
 a, b = b, a  
 print("a =", a)  
 print("b =", b)  

Summary

Swapping of two numbers is a foundational concept in Python programming. Python, being a high-level language, provides a concise and elegant way to do this through tuple unpacking. While older methods using temporary variables or arithmetic still work, the Pythonic way is recommended for clarity and simplicity.

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