Kotlin introductory notes (IV) circular statements (simple explanation of while, for)

Preface : This tutorial is best done with JAVA Study on the basis of

One 、while Use of statements

        while Use and java No different

Two 、for Use of statements

         Be careful ：kotlin Give up for - i loop , take java Of for ( x : xx ) Turned into for - in loop （ It's written a bit like c#, But it's much more flexible ）

So let's talk about that kotlin Characteristics of ：

kotlin characteristic ：

Section

1. Closed interval at both ends    eg. val range = 0..10 （ Can take 0 To 10, Closed interval at both ends ）
2. Front open back close interval    eg. vla range = 0 until 10 （ You can get it. 0 To 9, Front opening and back closing ）

step keyword

         By default ,for-in It will increase in the range 1. But if you want to jump some elements , have access to step keyword .

        Such as ：

fun main() {
    for(i in 0 until 10 step 2) {
        println(i)
    }
}

 downTo keyword

        Create a descending space

fun main() {
    for(i in 10 downTo 1) {
        println(i)
    }
}

        for More about will be explained later ...