Kotlin Functions

Basic Example :-

fun addNumbers(n1: Double, n2: Double): Int {   //Int is Returntype

    val sum = n1 + n2

    val sumInteger = sum.toInt()

    return sumInteger

}

fun addNumbers(n1: Double, n2: Double): Unit { //Returning Nothing & can be blank also

    val sum = n1 + n2                                                            (No need to define)

    val sumInteger = sum.toInt()

    return sumInteger

}

Function as Expression :-

fun max(a:Int, b:Int):Int {

if (a >b ) {

return a

}

else {

return b 

}

}

can be changed into -

fun max(a:Int, b:Int):Int = if (a>b) a else b

Default Function :- Interpolation

- Takes Default value when no arguments is passed.

main()

var result = findVolume(2,3)   //here takes default h as 10

print(result)

var result = findVolume(2,3,8)  //values already provided , so no default taken

print(result)

fun findVolume(l:Int,b:Int,h:Int=10) {  //takes default h as 10 if not provided

return l*b*h }

Named Parameter :-

No matter with sequence of arguments in function.

Name of Arguments will be same in calling and called function.

main()

findVolume(h=30,b-=5,l=7)

findVolume(b=22,l=9)

fun findVolume(l:Int,b=int,h:Int=10) {  //No matter of sequence, Default parameter also provided

print(lenght $l)

print(breadth $b)

print(height $h)

}

Extension Function :-

Add new function to any class in main.

New function will be static.

eg-1

main()  {

var student = Student()

println("passed status :" +student.ispassed(57)) 

println("passed status :" +student.isScholar(57))  }

 

fun Student.isScholar(mark :Int):Boolean {  //This is extension function

return mark > 95 }

class Student {

fun ispassed(mark : Int) : Boolean {

return mark > 40 }

main() {

var str1 = "man"

var str2 = "eats"

var str3 = "apple"

println(str3.add(str1,str2) 

fun String.add(s1:String,s2.String):String { //extension function 

return this + s1 + s2 }

*Extenstion function work String, Int etc as datatype is class in Kotlin

Infix Function :-

Same as Extension Function but work with Single Parameter.

prefix of Infix

main() {

val x:Int = 6

val y:Int = 10

val greaterVal = x greater y   //x.greater(y) new way of defining fun

println(greaterVal)

infix funtion Int.greater(other.Int) : Int {

if (this>other) 

return this

else

return other } }

Tailrec Fuction :-   

use Recursion.(calling function within own function)

Avoid Stackoverflow exception

tailrec fun findFixPoint(x: Double = 1.0): Double

        = if (Math.abs(x - Math.cos(x)) < eps) x else findFixPoint(Math.cos(x))