Kotlin Video Series – Functions (Part 1)

This is the seventh part of the video series on Kotlin language.
Read and watch the other parts here.

We discuss writing functions in Kotlin language.

We’ve been writing a main function in all these examples. So that should have already given us some idea about the syntax of the functions. A Function is written using the fun keyword.

fun main(args:Array<String>){
   println(sayHello("Sam"))
}
fun sayHello(name:String):String{
    return "Hello $name"
}

You can omit the return type of a function if doesn’t return anything.

  fun print(message:String){
	println(message)
  }

We can also make a function that does not return anything to return Unit, which means Nothing. Unit can be used in Generics, which we will discuss later.

   fun printAgain(message:String):Unit{
	println(message)
}

Functions can be written as expressions, like our if-else and when-else constructs. An add function thats adds two numbers can be written as an expression like this.

  //Normal function 
  fun add(x:Int,y:Int):Int{
	return x + y
   }

   //Expressions
   fun add(x:Int,y:Int) = x + y
   fun square(x:Int) = x * x
}

You can find the video here.