Reverse Numbers in Java: 2 Loop Examples When manipulating numbers in Java, loops are essential. Learn how to reverse a number using while and for loops with 2 easy examples.

Unleashing the Power of Loops in Java

Reversing Numbers with Ease

When it comes to manipulating numbers in Java, loops are an essential tool in every programmer’s arsenal. In this article, we’ll explore two examples of how to reverse a number using while and for loops, respectively.

The While Loop Approach

Imagine you want to reverse a number, say 1234. How would you do it? One way is to use a while loop, which continues to execute as long as a certain condition is true. In this case, the condition is num!= 0, where num is the original number.

Here’s how it works:

• Take the remainder of num divided by 10 and store it in a variable digit. This gives you the last digit of num.
• Add digit to a variable reversed after multiplying it by 10. This effectively adds a new place to the reversed number.
• Divide num by 10 to remove the last digit.
• Repeat steps 1-3 until num becomes 0.

Let’s see this in action:

| Iteration | digit | reversed | num |
| — | — | — | — |
| 1 | 4 | 4 | 123 |
| 2 | 3 | 43 | 12 |
| 3 | 2 | 432 | 1 |
| 4 | 1 | 4321 | 0 |

As you can see, the while loop successfully reverses the number 1234 to 4321.

The For Loop Alternative

But what if you want to use a for loop instead? The good news is that you can achieve the same result with a few tweaks.

Here’s the modified code:

• No initialization expression is needed inside the loop since num is already initialized before the loop.
• The test expression remains the same (num!= 0).
• The update/increment expression contains num /= 10, which removes the last digit of num after each iteration.

The result is the same: the reversed number 4321.

Taking It Further

Reversing numbers is just the tip of the iceberg. With loops, you can perform a wide range of tasks, from reversing sentences to solving complex algorithms. The possibilities are endless!

Explore More

Want to learn more about recursion in Java? Check out our article on reversing a sentence using recursion.