Tutorials

Reverse Number

In this tutorial, our task is:

• to reverse the given number
• print the reversed number

Example:

Give number: 1345

Reverse number: 5431

Java program to reverse the given number.

``````
public class ReverseNumber {

public static void main(String[] args) {

int n = 1345;
int reverse=0;

while(n!=0){
reverse = reverse*10 + n%10;
n = n/10;
}

System.out.println(reverse);
}
}``````

OUTPUT

5431

How the above code works?

We have number, n = 1345

We have another variable reverse purposefully assigned a initial value 0.

Till n is not zero, the while loop will continue to operate. Let's see its processing methodology:

1st iteration: Since 1345!=0 is true, so control enters loop.

Now we have,

reverse = reverse*10 + n%10;

reverse = 0*10 + 1345%10

reverse = 0 + 5;

reverse = 5;

Next operation is, n = n/10;

n = 1345/10

n = 134

2nd iteration: Now n = 134 and since 134!=0 is true, so control enters loop.

reverse = 5*10 + 134%10;

reverse = 50 + 4;

reverse = 54;

Next operation is, n = n/10

n = 134/10

n= 13;

3rd iteration: Now n = 13 and since 13!=0 is true, so control enters loop.

reverse = 54*10 + 13%10

reverse = 540 + 3

reverse = 543

Next operation is, n = n/10;

n = 13/10

n = 1;

4th iteration: Now n = 1 and since 1!=0 is true, so control enters loop.

reverse = 543*10 + 1%10;

reverse = 543 +1;

reverse = 5431;

Next operation is, n = n/10;

n = 1/10;

n = 0;

5th iteration: Now n = 0 and since 0!=0 is false, so control doesnot pass inside while loop and it ends.

The value of reverse is printed: 5431 which is the reverse of the given number.