equality operator

equalOperatorLearning.kt

package basics


/*
1. structure equality  -> == or equals -> both are same here -> value comp -> equality of 2 object in terms of value
2. reference equality -> === -> memory location comparison -> two reference variable points to same object

negative of == ->  !=
negative of === -> !==

 */


fun main() {
    objectCompareFun()
    stringCompareFun()
}

fun objectCompareFun() {
    class User {
        var foo = 1  //some property
    }

    var u1 = User() //user1 obj
    var u2 = User() //user2 obj

    println(u1 == u2) //false : user1.equals(user2)
    println(u1 === u2) //false : user1 and user2 reference to different object

    var u3 = User() //user3
    var u4 = u3 //user3

    println(u3 == u4) //true : user3.equals(user3)
    println(u3 === u4) //true : u3 and u4 reference to same object

}

fun stringCompareFun() {
    val str1 = "Hello"
    val str2 = "Hello"
    val str3 = "Hello World"

    println(str1 == str2) //true : "Hello".equals("Hello")
    println(str1 == str3) //false : "Hello".equals("Hello World")
    println(str1 === str2) //true : str1 and str2 references same object
    println(str1 === str3) //false : str1 and str3 references to different object

    val num1 = 10
    val num2 = 10
    val num3 = 20

    println(num1 == num2)//true: 10.equals(10)
    println(num1 === num2)//true: num1 and num2 references same object
}