# Kotlin Program to Convert Binary Number to Octal and vice-versa

## Example 1: Program to Convert Binary to Octal

In this program, we will first convert binary number to decimal. Then, the decimal number is converted to octal.

``````fun main(args: Array<String>) {
val binary: Long = 101001
val octal = convertBinarytoOctal(binary)
println("\$binary in binary = \$octal in octal")
}

fun convertBinarytoOctal(binaryNumber: Long): Int {
var binaryNumber = binaryNumber
var octalNumber = 0
var decimalNumber = 0
var i = 0

while (binaryNumber.toInt() != 0) {
decimalNumber += (binaryNumber % 10 * Math.pow(2.0, i.toDouble())).toInt()
++i
binaryNumber /= 10
}

i = 1

while (decimalNumber != 0) {
octalNumber += decimalNumber % 8 * i
decimalNumber /= 8
i *= 10
}

return octalNumber
}``````

When you run the program, the output will be:

`101001 in binary = 51 in octal`

This conversion takes place as:

```Binary To Decimal
1 * 25 + 0 * 24 + 1 * 23 + 0 * 22 + 0 * 21 + 1 * 20 = 41

Decimal to Octal
8 | 41
8 | 5 -- 1
8 | 0 -- 5
(51)
```

## Example 2: Program to Convert Octal to Binary

In this program, the octal number to decimal to decimal at first. Then, the decimal number is converted to binary number.

``````fun main(args: Array<String>) {
val octal = 67
val binary = convertOctalToBinary(octal)
println("\$octal in octal = \$binary in binary")
}

fun convertOctalToBinary(octalNumber: Int): Long {
var octalNumber = octalNumber
var decimalNumber = 0
var i = 0
var binaryNumber: Long = 0

while (octalNumber != 0) {
decimalNumber += (octalNumber % 10 * Math.pow(8.0, i.toDouble())).toInt()
++i
octalNumber /= 10
}

i = 1

while (decimalNumber != 0) {
binaryNumber += (decimalNumber % 2 * i).toLong()
decimalNumber /= 2
i *= 10
}

return binaryNumber
}``````

When you run the program, the output will be:

`67 in octal = 110111 in binary`

This conversion takes place as:

```Octal To Decimal
6 * 81 + 7 * 80 = 55

Decimal to Binary
2 | 55
2 | 27 -- 1
2 | 13 -- 1
2 | 6  -- 1
2 | 3  -- 0
2 | 1  -- 1
2 | 0  -- 1
(110111)
```

Here's the equivalent Java code: Java Program to Convert Binary to Octal and vice-versa