Kotlin Program to Reverse a Number

In this article, we will understand how to print an integer in Kotlin. The reverse of a number is computed using a loop and arithmetic operator % and /.

Below is a demonstration of the same −

Suppose our input is −

The number : 123456

The desired output would be −

The result is 654321

Algorithm

• Step 1 − START

• Step 2 − Declare two integer values namely myInput and reversed.

• Step 3 − Define the values

• Step 4 − Run a while loop

• Step 5 − Use modulus of 10 and get remainder for ‘myTemp’ .

• Step 6 − Multiply ‘reversed’ with 10, and add to ‘myTemp’, and make that the current ‘reversed’.

• Step 7 − Divide ‘myInput’ by 10, and make that the current ‘myInput'.

• Step 8 − Display the result

• Step 9 − Stop

Example 1

In this example, we will reverse a number using a while loop. First, let us declare a variable for the input i.e. the number we will reverse. We have also declared a variable for the output i.e. reversed number  −

var myInput = 123456
var reversed = 0

Now, using a while loop reverse the number. Loop till the input != 0;

while (myInput != 0) {
   val myTemp = myInput % 10
   reversed = reversed * 10 + myTemp
   myInput /= 10
}

Let us now see the complete example to reverse a number using a while loop −

fun main() {
   var myInput = 123456
   var reversed = 0
   println("The number is defined as: $myInput")

   while (myInput != 0) {
      val myTemp = myInput % 10
      reversed = reversed * 10 + myTemp
      myInput /= 10
   }
   println("The reversed number is: $reversed")
}

Output

The number is defined as: 123456
The reversed number is: 654321

Example 2

In this example, we will reverse a number.

fun main() {
   var myInput = 123456
   println("The number is defined as: $myInput")
   reverseNumber(myInput)
}
fun reverseNumber(input: Int) {
   var myInput = input
   var reversed = 0
   
   while (myInput != 0) {
      val myTemp = myInput % 10
      reversed = reversed * 10 + myTemp
      myInput /= 10
   }
   println("The reversed number is: $reversed")
}

Output

The number is defined as: 123456
The reversed number is: 654321