Convert an integer to a binary string in Kotlin

This article explores different ways to convert an integer to a binary string of a specific length in Kotlin. The solution should left-pad the binary string with leading 0’s.

1. Using `Integer.toBinaryString()` function

The standard way to get a binary string from an integer is with Integer.toBinaryString(). To get a binary string of a specific length with leading 0’s, you can take the help of String.format() with the replace() function.

fun toBinary(x: Int, len: Int): String {

return String.format(

"%" + len + "s",

Integer.toBinaryString(x)

).replace(" ".toRegex(), "0")

}

fun main() {

var num = 10000

var len = 16

println(toBinary(num, len)) // 0010011100010000

}

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2. Using StringBuilder

You can also write your own routine for converting an integer to a binary string of a specific length with leading 0’s.

fun toBinary(x: Int, len: Int): String {

val result = StringBuilder()

for (i in len - 1 downTo 0)

{

val mask = 1 shl i

result.append(if (x and mask != 0) 1 else 0)

}

return result.toString()

}

fun main() {

var num = 10000

var len = 16

println(toBinary(num, len)) // 0010011100010000

}

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3. Using Character Array

Alternatively, you can use a character array instead of a StringBuilder.

fun toBinary(x: Int, len: Int): String {

val buffer = CharArray(len)

for (i in len - 1 downTo 0)

{

val mask = 1 shl i

buffer[len - 1 - i] = if (x and mask != 0) '1' else '0'

}

return String(buffer)

}

fun main() {

var num = 10000

var len = 16

println(toBinary(num, len)) // 0010011100010000

}

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That’s all about converting an integer to a binary string in Kotlin.

Convert an integer to a binary string in Kotlin

1. Using Integer.toBinaryString() function

2. Using StringBuilder

3. Using Character Array

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1. Using `Integer.toBinaryString()` function