【Kotlin】Kotlin笔记2-程序的逻辑控制(if,when,循环语句)

矫情吗；* 2022-11-16 02:47 227阅读 0赞

### Kotlin笔记-程序的逻辑控制 ###

**2. 程序的逻辑控制**

*  **if条件语句**

> **if**

`Example:`

fun largerNumber3(num1: Int, num2: Int): Int {
        var value = 0
        if (num1 > num2) {
            value = num1
        } else
            value = num2
    
        return value
    }

*语法糖*

fun largerNumber4(num1: Int, num2: Int): Int {
        val value = if (num1 > num2) {
            num1
        } else {
            num2
        }
        return value
    }

fun largerNumber5(num1: Int, num2: Int): Int {
        return if (num1 > num2)
            num1
        else
            num2
    }

fun largerNumber6(num1: Int, num2: Int) = if (num1 > num2) {
        num1
    } else {
        num2
    }

fun largerNumber7(num1: Int, num2: Int) = if (num1 > num2) num1 else num2

--------------------

*  **when条件语句**

> **when**

`Example if:`

fun getScore(name: String) = if (name == "Tom") 86
    else if (name == "Jim") 77
    else if (name == "Jack") 95
    else if (name == "Lily") 100
    else 0

`Example when:`

fun getScore1(name: String) = when (name) {
        "Tom" -> 86
        "Jim" -> 77
        "Jack" -> 95
        "Lily" -> 100
        else -> 0
    }

*when允许传入任意类型参数,格式:*

匹配值 -> { 执行逻辑 }

*类型匹配*

fun checkNumber(num: Number) {
        when (num) {
            is Int -> println("number is Int")
            is Double -> println("number is Double")
            else -> println("number not support")
        }
    }

> **is** = instanseof(Java)

*不传参when*

fun getScore2(name: String)=when{
        name=="Tom"->86
        name=="Jim"->77
        name=="Jack"->95
        name=="Lily"->100
        else->0
    }

`特殊场景 example:`

name.startsWith("Tom")->86
        name=="Jim"->77
        name=="Jack"->95
        name=="Lily"->100
        else->0
    }

--------------------

*  循环语句

> **while**

> **for** \->for-in

*闭区间*

va range = 0..10 //[0,10]

fun circulation(){
        for (i in 1..10){
            println(i)
        }
    }

*左闭右开*

> **until**

val range 0 until 10