repeat()

Suppose you wish to execute a piece of code 5 times, and you don’t need to count out each iteration. In such a case, you don’t have to use a for loop. Instead, you can do this:

repeat(5) {
    println("Hello World!")
}

[Run this code]

The interesting thing about this example is that it is a function call rather than a distinct looping structure like for or while.

The repeat() function expects to be given two arguments. The first is a count of how many repetitions are required. The second argument is the code to be executed repeatedly, typically provided in the form of a lambda expression.

We will discuss lambda expressions in more detail later, but for now you can think of them as ‘anonymous functions’. In this example, the left and right braces define the extent of the lambda expression. The lambda expression is very simple; all it does is call the println() function.

What may be slightly confusing to you is that this piece of code appears outside the parentheses, making it look like it isn’t being passed in as an argument of the function call!

In cases where a function expects to be supplied with a piece of code as the final argument of a call to that function, and that code is written as a lambda expression, Kotlin allows us to move the lambda expression outside the parentheses, as we have done here.