Dealing null values

dealing_null.kt

fun main() {

    val a: Int? = null

    println(a)

    var b: String? = "Hi"

    // !! means non null assertion
    for (char in b!!) {
        if (char == 'i') {
            b = null
        }
    }

    println(b?.length) // Safe Call - prevent from throwing exception

    val c = b?.length ?: 0 // usage of elvis
    println(c)

    val d: String = b!! // non-null assertion
    print(d.length)
}