Instruction

What Is a Function?

A function is a block of code that performs a specific task. Whenever your app needs to execute the task, you call the function.

Kotlin includes two types of functions: predefined and user-defined functions.

Predefined Functions

These are functions provided by the Kotlin standard library. They’re readily available for use. For example, println() :

fun main() {
  println("Hello Kotlin!!")
}

This code prints “Hello Kotlin!!” to the screen, like this:

Hello Kotlin!!

The max() function provided in the Math package compares two numbers and returns the larger one.

import kotlin.math.max

fun main() {
  val largest = max(3, 4)
  println("The largest number is $largest.")
}

max() takes two parameters of type Int. In the example above, the values 3 and 4 are passed as arguments. You’ll learn more about parameters in the upcoming lessons.

The code above prints the following to the screen:

The largest number is 4.

You’ve now learned some basics about functions in Kotlin. In the next section, you’ll learn how to create user-defined functions.