Kotlin Syntax

In the previous chapter, we created a Kotlin file called Main.kt, and we used the following code to print "Hello World" to the screen:

Example

fun main() {
  println("Hello World")
}

Try it Yourself »

Example explained

The fun keyword is used to declare a function. A function is a block of code designed to perform a particular task. In the example above, it declares the main() function.

The main() function is something you will see in every Kotlin program. This function is used to execute code. Any code inside the main() function's curly brackets {} will be executed.

For example, the println() function is inside the main() function, meaning that this will be executed. The println() function is used to output/print text, and in our example it will output "Hello World".

Good To Know: In Kotlin, code statements do not have to end with a semicolon (;) (which is often required for other programming languages, such as Java, C++, C#, etc.).

Main Parameters

Before Kotlin version 1.3, it was required to use the main() function with parameters, like: fun main(args : Array<String>). The example above had to be written like this to work:

Example

fun main(args : Array<String>) {
  println("Hello World")
}

Try it Yourself »

Note: This is no longer required, and the program will run fine without it. However, it will not do any harm if you have been using it in the past, and will continue to use it.

❮ Previous Next ❯