Leverage Kotlin Functions & Lambdas

May 22 2024 · Kotlin 1.9.24, Android 14, Kotlin Playground

Lesson 02: Understand Function Parameters

Demo

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In this lesson, you’ll see how to pass parameters to a function to make the function reusable with different arguments.

fun greetings(name: String, favLanguage: String) {
  println("Hello! I am $name. My favorite language is $favLanguage.")
}

fun main() {
  greetings("Bilbo", "Kotlin")
}

Named Arguments

Recently I moved to a house close to a road used by heavy trucks. This afternoon so many trucks were passing. I was distracted just a bit and wrote the following code:

fun main() {
  greetings("Kotlin", "Bilbo")
}

fun main() {
  greetings(favLanguage = "Kotlin", name = "Bilbo")
}

Default Arguments

Function parameters can have default values. For example, you can pass Kotlin as the default value of the favLanguage parameter:

fun greetings(name: String, favLanguage: String = "Kotlin") {
  println("Hello! I am $name. My favourite is language $favLanguage.")
}

fun main() {
  greetings(name = "Bilbo")
}

fun main() {
  greetings(name = "Bilbo", favLanguage = "Swift")
}

Returning Values

You’ve seen how to pass parameters to a function and used named and default arguments. Now, you’ll create a function that returns a value. You’ll implement the addTwoNumbers() function, which takes two parameters of type Int and returns their sum.

fun addTwoNumbers(num1: Int, num2: Int): Int {
  val sum = num1 + num2
  return sum
}

fun main() {
  val sumOfTwoNumbers = addTwoNumbers(7, 13)
  println("The sum is $sumOfTwoNumbers")
}

fun addTwoNumbers(num1: Int, num2: Int): Int = num1 + num2

import kotlin.math.sqrt

...

fun findSquareRoot(num: Float): Float {
  val squareRoot = sqrt(num)
  return squareRoot
}

fun main() {
  val squareRoot = findSquareRoot(576f)
  println("Square root => $squareRoot")
}

Square root => 24.0

fun main() {
  val squareRoot = findSquareRoot(729f)
  println("Square root => $squareRoot")
}

Square root => 27.0

fun findSquareRoot(num: Float): Float  = sqrt(num)
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