# Reverse number in C using while loop

In the world of programming, understanding how to reverse number is a fundamental skill. In this blog, we’ll explore how to Rreverse numbers in C using a while loop. Whether you’re new to programming or looking to expand your skills, this informative blog is for you!

First, understand what it means to reverse a number. Reversing a number means rearranging its digits in the opposite order. For example, if we have the number 123, reversing it would give us 321.

## C programming to reverse a number

Now, let’s see how we can achieve this in C programming using a while loop. The while loop is a control flow statement that allows code to be executed repeatedly based on a given condition. We’ll use this loop to iterate through the digits of the number and reverse them.

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### C Program Reverse a number using while loop

```#include <stdio.h>

int main() {
int num, reversedNum = 0, remainder;

// Input the number from the user
printf("Enter an integer: ");
scanf("%d", &num);

// Reversing the number using a while loop
while (num != 0) {
remainder = num % 10;
reversedNum = reversedNum * 10 + remainder;
num /= 10;
}

// Print the reversed number
printf("Reversed number: %d\n", reversedNum);

return 0;
}```

Explanation of the code:

This C code snippet demonstrates how to reverse a given integer entered by the user using a while loop. Here’s how it works:

1. We declare three integer variables: `num` to store the original number entered by the user, `reversedNum` to store the reversed number, and `remainder` to store the remainder of the division operation.

2. The user is prompted to input an integer using the `printf()` function and read it using the `scanf()` function.

3. Inside the while loop, we continue looping as long as the value of `num` is not equal to 0.

4. In each iteration of the loop, we extract the last digit of the number `num` using the modulus operator `%` and store it in the variable `remainder`.

5. We then update the value of `reversedNum` by multiplying it by 10 and adding the value of `remainder`.

6. Next, we update the value of `num` by dividing it by 10, effectively removing the last digit.

7. This process continues until the original number `num` becomes 0.

8. Once the loop exits, we print the reversed number stored in the variable `reversedNum` using the `printf()` function.

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#### Output:

``Enter an integer: 1234567Reversed number: 7654321``

## Interview question about a reverse number in C

Below given are some commonly asked interview questions related to reversing numbers in C using a while loop:

1. What is the purpose of reversing a number in C programming?

Answer: Reversing a number involves rearranging its digits in the opposite order. It’s a fundamental programming concept used in various applications, such as cryptography, data validation, and numerical analysis.

2. How do you reverse a number in C using a while loop?

Answer: To reverse a number in C using a while loop, you repeatedly extract the last digit of the number using the modulus operator (%) and accumulate it in a separate variable by multiplying it by 10. After each iteration, divide the original number by 10 until it becomes zero.

3. What are some common errors or pitfalls to avoid when implementing the reverse number algorithm in C?

Answer: Common errors include forgetting to initialize variables, incorrectly updating the loop condition, or mishandling negative numbers. It’s essential to carefully debug the code and handle edge cases, such as single-digit numbers or zero.

4. Can you explain the role of the modulus operator (%) in reversing a number?

Answer: The modulus operator (%) returns the remainder when one number is divided by another. By using the modulus operator with 10, we can extract the last digit of a number, which is essential for reversing the number.

5. How do you handle negative numbers when reversing a number in C?

Answer: When dealing with negative numbers, we typically reverse the absolute value of the number and then apply the appropriate sign (+ or -) to the reversed result based on the original number’s sign.

### Domain for reversing numbers in C using a while loop

The domain for reversing numbers in C using a while loop encompasses various fields in computer science and software engineering, including:

1. Algorithm Design and Analysis

2. Data Structures

3. Numerical Computing

4. Embedded Systems

5. Cryptography

6. Data Validation and Verification

7. Game Development

8. Text Processing and Parsing

9. Computer Graphics

10. System Programming

We hope that in our blog of ‘Reverse number in C using while loop’ helps you to understand the concept of reversing numbers in C, highlighting its educational and practical significance. We encourage you to experiment with the provided code on the compiler and also enjoy the benefit of the blog and courses available on Newtum to enhance your programming skills. Happy coding!

## Reverse number in C using while loop- FAQ

1. What is the purpose of reversing a number in C programming?

Answer- Reversing a number involves rearranging its digits, serving as a fundamental concept used in various applications like cryptography and data validation.

2. How do you reverse a number in C using a while loop?

Answer- To reverse a number, repeatedly extract the last digit using the modulus operator (%) and accumulate it in a separate variable by multiplying it by 10.

3. What are common errors to avoid when implementing the reverse number algorithm in C?

Answer- Common errors include mishandling negative numbers, forgetting to initialize variables, and incorrectly updating the loop condition.

4. What is the role of the modulus operator (%) in reversing a number?

Answer- The modulus operator (%) helps extract the last digit of a number, which is crucial for reversing the number in C programming.

5. How do you handle negative numbers when reversing a number in C?

Answer- With negative numbers, reverse the absolute value of the number and then apply the appropriate sign based on the original number’s sign.