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How to Swap Variables in Python – Complete Worksheet with Solutions

Swapping two variables is a fundamental programming concept that every beginner should master. Whether you’re preparing for coding interviews or building Python applications, knowing how to exchange variable values efficiently is essential.

In this tutorial, we’ll explore two simple methods to swap variables in Python:

  1. Using a Temporary Variable
  2. Direct Swapping Without a Temporary Variable

Let’s dive in!

Why Do We Need to Swap Variables?

Swapping variables means exchanging their values. For example:

  • Before Swap:
    • a = 5
    • b = 10
  • After Swap:
    • a = 10
    • b = 5

This operation is useful in:

  • Sorting algorithms
  • Data manipulation
  • Shuffling values in games
  • Optimizing memory usage

Method 1: Swapping Using a Temporary Variable

The most straightforward way to swap two variables is by using a third temporary variable.

Step-by-Step Explanation:

  1. Store the value of a in a temporary variable (temp).
  2. Assign b’s value to a.
  3. Assign temp’s value (original a) to b.

Python Code Example:

a = 5  
b = 10  

# Swapping using a temporary variable  
temp = a  
a = b  
b = temp  

print("After swapping:")  
print("a =", a)  # Output: 10  
print("b =", b)  # Output: 5

Why This Works:

  • The temporary variable (temp) holds the original value of a before it gets overwritten.
  • This ensures no data is lost during the swap.

Method 2: Swapping Without a Temporary Variable

Python allows a more concise way to swap variables without needing a temporary variable.

How It Works:

  • Python evaluates the right-hand side first (b, a), creating a tuple.
  • Then, it unpacks the values into a and b.

Python Code Example:

a = 5  
b = 10  

# Swapping without a temporary variable  
a, b = b, a  

print("After swapping:")  
print("a =", a)  # Output: 10  
print("b =", b)  # Output: 5

Advantages:

  • Cleaner and shorter syntax.
  • No extra memory used for a temporary variable.

Common Mistake to Avoid

Many beginners try swapping like this:

a = b  
b = a

❌ Why It Fails:

  • After a = b, both variables hold the same value.
  • The original value of a is lost, so the swap doesn’t work.

✅ Always use one of the correct methods above!

Conclusion

Now you know two efficient ways to swap variables in Python:

  1. Using a temporary variable (best for readability).
  2. Direct swapping (most Pythonic and concise).

Try implementing these methods in your own programs! If you prefer a visual explanation, check out our video tutorial below.

📹 Watch the Video Tutorial Here

FAQs

Q: Can we swap more than two variables at once?
A: Yes! Example:

a, b, c = b, c, a

Q: Does swapping work with different data types?
A: Yes, Python allows swapping any data types (e.g., int, str, list).

Q: Which method is faster?
A: The direct swap (a, b = b, a) is slightly faster and more memory-efficient.

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