# Kotlin countOneBits()

## Kotlin countOneBits()

In Kotlin, the `countOneBits()` function is used to count the number of set (1) bits in the binary representation of the numeric value.

This function is valuable in various bitwise operations and algorithms where knowledge of the number of set bits is required.

In this tutorial, we’ll explore the syntax of the `countOneBits()` function and provide examples of its usage in Kotlin.

## Syntax

The syntax of the `countOneBits()` function is:

``````fun Byte.countOneBits(): Int
fun Short.countOneBits(): Int
fun UInt.countOneBits(): Int
fun ULong.countOneBits(): Int
fun UByte.countOneBits(): Int
fun UShort.countOneBits(): Int
fun Int.countOneBits(): Int
fun Long.countOneBits(): Int``````

The `countOneBits()` function is an extension function for the specified numeric classes, and returns the count of set (1) bits in the binary representation of this value.

## Examples

### 1. Using countOneBits() for Population Count

In this example, we’ll use `countOneBits()` to calculate the population count (number of set bits) in an integer.

Kotlin Program

``````fun main() {
val number = 42
val populationCount = number.countOneBits()
println("The population count of \$number is \$populationCount")
}``````

Output

``The population count of 42 is 3``

In this example, the `countOneBits()` function is used to calculate the population count (number of set bits) in the binary representation of the given integer. The result is then printed.

## Summary

In this tutorial, we’ve covered the `countOneBits()` function in Kotlin, its syntax, and how to use it for counting set (1) bits in the binary representation of an integer. This function is useful in various scenarios where you need to manipulate or analyze the binary representation of integers.