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Kotlin Data types and declaration

Similar to other programming languages, you can define variables in Kotlin which represents a conainer to store data.

In Kotlin, To declare a variable you can either use var or val keywords.

Syntax of Variable Declaration

var variableName = value
val variableName = value

The difference between var and val is that variables declared with the var keyword can be changed/modified, while val variables cannot.

Kotlin does automatically knows that data type of the variable, unlike many other programming language Kotlin does not need to have data type (like Int, String, Bool...) to be specified when declaring a variable.

Example of Kotlin Variable declaration with var

fun main() {
  var name = "John"      // String (text)
  val age = 35          // Int (number)

  println(name)       // Print the value of name
  println(age)       // Print the value of age



Example of Kotlin Variable declaration with val

fun main() {
  val name = "John"
  name = "William"


error: val cannot be reassigned
name = "William"


In this page (written and validated by ) you learned about Kotlin Data types and declaration . What's Next? If you are interested in completing Kotlin tutorial, your next topic will be learning about: Kotlin Declare constant.

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