Kodebits Day 83: Smart Cast

What is the output?

fun main() {
  val x: Any = "Kotlin"
  if (x is String) {
    println(x.length)
  }
}

Try it in the online Kotlin Playground →

[spoiler title="Solution"]

Answer:

6

Explanation:

Smart casts automatically convert types after an is check. Inside the if block, x is treated as String, so .length is accessible without explicit casting.

[/spoiler]

Further Reading

• Learn the Basics of the Kotlin Language
• Use Kotlin Classes