Parse a binary string as a number in Kotlin

This article explores different ways to parse a binary string as a number in Kotlin.

A simple solution to parse the string as a number in the specified radix is using the toInt() function. This is demonstrated below:

fun main() {

val binary = "11111111"

val i = binary.toInt(2)

println(i) // 255

}

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The maximum value that can be parsed by the toInt() function is 2³¹-1 (01111111 11111111 11111111 11111111 in binary), as shown below:

fun main() {

val binary = "01111111111111111111111111111111"

val i = binary.toInt(2)

println(i) // 2147483647

}

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To parse the binary string 11111111 11111111 11111111 11111111 which represent the decimal value -1, use the Integer.parseUnsignedInt() function:

fun main() {

val binary = "11111111111111111111111111111111"

val i = Integer.parseUnsignedInt(binary, 2)

println(i) // -1

}

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Alternatively, the toLong() function can be used in the following manner:

fun main() {

val binary = "11111111111111111111111111111111"

val i = binary.toLong(2).toInt()

println(i) // -1

}

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Finally, we can write a custom method to convert a binary string to a decimal. It can be implemented as follows:

import kotlin.math.pow

fun toInteger(binary: String): Int {

var decimal: Long = 0

for (i in binary.length - 1 downTo 0) {

if (binary[i] == '1') {

decimal += 2.0.pow((binary.length - i - 1).toDouble()).toLong()

}

return decimal.toInt()

}

fun main() {

val binary = "11111111111111111111111111111111"

val i = toInteger(binary)

println(i) // -1

}

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That’s all about parsing a binary string as a number in Kotlin.

Parse a binary string as a number in Kotlin

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