C# - Reverse Digits of a Number

Learn: How to reverse digits of a given number using C# program, this post has solved program with explanation.
Submitted by Ridhima Agarwal, on September 17, 2017 [Last updated : March 19, 2023]

Given an integer number and we have to print its digits in reverse order.

Example

```Input: 721
Output: 127
```

In this program, we are extracting digits one by one and calculating them to make a complete number (which will be reverse number).

C# program to reverse digits of a given number

```using System;

namespace system {
class reverse {
static void Main(String[] args) {
int a = 721, rev = 0, b;

//condition to check if the number is not 0
while (a != 0) {
b = a % 10; //extract a digit
rev = (rev * 10) + b; //reverse the digits logic
a = a / 10; //remained number
}
Console.WriteLine("The reverse of the number is: " + rev);
}
}
}
```

Output

```The reverse of the number is: 127
```

Explanation

```
Inital value of a (input number): a = 721
Inital value of rev = 0

Iteration 1:
b = a%10  → 721%10 = 1
rev = (rev*10)+b  → (0*10)+1 = 1
a = a/10 → 721/10 = 72

Iteration 2:
b = a%10  → 72%10 = 2
rev = (rev*10)+b  → (1*10)+2 = 12
a = a/10 → 72/10 = 7

Iteration 3:
b = a%10  → 7%10 = 7
rev = (rev*10)+b  → (12*10)+7 = 127
a = a/10 → 7/10 = 0

Now, the value of a is "0", condition will be fasle
Output will be 127.
```