Basic Syntax - Kotlin Programming Language If, Loop, Functions

Defining functions

Function having two Int parameters with Int return type:

fun sum(a: Int, b: Int): Int 

{

    return a + b

}

Function with an expression body and inferred return type:

fun sum(a: Int, b: Int) = a + b

Function returning no meaningful value:

fun printSum(a: Int, b: Int): Unit 

{

    println("sum of $a and $b is ${a + b}")

}

Unit return type can be omitted:

fun printSum(a: Int, b: Int) 

{

    println("sum of $a and $b is ${a + b}")

}

Defining variables

Assign-once (read-only) local variable:

val a: Int = 1  // immediate assignment

val b = 2   // `Int` type is inferred

val c: Int  // Type required when no initializer is provided

c = 3       // deferred assignment

Mutable variable:

var x = 5 // `Int` type is inferred

x += 1

Top-level variables:

val PI = 3.14

var x = 0

​fun incrementX()

{

    x += 1

}

Comments

Just like Java and JavaScript, Kotlin supports end-of-line and block comments.

// This is an end-of-line comment

/* This is a block comment

   on multiple lines. */

Unlike Java, block comments in Kotlin can be nested.

Using string templates

var a = 1

// simple name in template:

val s1 = "a is $a"

​

a = 2

// arbitrary expression in template:

val s2 = "${s1.replace("is", "was")}, but now is $a"

Using conditional expressions

fun maxOf(a: Int, b: Int): Int

{

    if (a > b) {

        return a

    } else {

        return b

    }

}

Using if as an expression:

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

Hello Reader

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Thank you Safe & Happy Coding. :)