03. 函数

1. 可以传递数组对象并修改

fun changeArray( game:Array<String>){
    game[1]="翻跟头"
}

fun main(args: Array<String>) {
    val games= arrayOf("吃饭","睡觉","打豆豆")
    changeArray(games)
    for (game in games) {
        print(game)
    }
}

输出：

吃饭翻跟头打豆豆

2. 改变基本数据类型是否会影响引用

fun changeArray( game:Array<String>){
    game[1]="翻跟头"
}

fun main(args: Array<String>) {
    var eat="吃饭"
    val games= arrayOf(eat,"睡觉","打豆豆")
    changeArray(games)
    eat="吃水果"
    for (game in games) {
        print(game)
    }
}

输出：

吃饭翻跟头打豆豆

结论

基本类型向对象中传递时，是拷贝内存中的数据，持有副本，而不是持有原基本类型的引用。

3. 函数的参数为基本类型时

默认val 只读状态，不可修改，编译器报错

fun changStr(str:String){
    str="test" //编译器报错
}

4. for循环的几种用法

4.1 遍历元素和下标

fun main(args: Array<String>) {
    val games = arrayOf("石头", "剪刀", "布")

    for (game in games) {
        print(game)
    }
    println()
    for(index in 0..games.size){
        print(index)
    }
    println()

    for(item in games.iterator()){
        print(item)
    }
    println()
    for((index,item) in games.withIndex()){
        print("$index: $item ")
    }
}

4.2 不包含右值的循环

和使用循环一个意思

fun main(args: Array<String>) {
    val games = arrayOf("石头", "剪刀", "布")
    for(index in  0 until games.size){
        println(index)
    }
}

4.3 逆序循环

fun main(args: Array<String>) {
    val games = arrayOf("石头", "剪刀", "布")
    for(index in  games.size-1  downTo  0){
        println(index)
    }
}

输出

2 1 0

4.4 step

跳过范围内的

fun main(args: Array<String>) {
    val games = arrayOf("石头", "剪刀", "布")
    for(index in  games.indices step 2){
        println(index)
    }
}

输出

0
2

石头剪刀布游戏

fun main(args: Array<String>) {
    val games = arrayOf("石头", "剪刀", "布")
    val me = Player()
    val robot = Player(name = "机器人")
    println("请输入玩家名称：")
    me.name = readLine() ?: "player"
    Thread{
        while (true) {
            println("-----------------------\n\n")
            //获取我出的拳
//        me.value = getMeValue(games)  //手动出拳
            me.value = getRobotValue(games)  //机器人自己出拳
            //获取机器人出拳
            robot.value = getRobotValue(games)
            //判决谁赢了
            judgment(me, robot)
        //    Thread.sleep(1000) // 一秒出一次
        }
    }.start()

}

fun judgment(player: Player, player1: Player) {
    println("${player.name}出了${player.value}")
    println("${player1.name}出了${player1.value}")
    if (player.value == player1.value) {
        println("平局")
    } else if (player.value == "石头" && player1.value == "剪刀" || player.value == "剪刀" && player1.value == "布" || player.value == "布" && player1.value == "石头") {
        player.victories += 1
    } else {
        player1.victories += 1
    }
    println("${player.name} 胜${player.victories}场")
    println("${player1.name} 胜${player1.victories}场")
}

data class Player(var name: String = "默认玩家", var value: String = "石头", var victories: Int = 0)


fun getMeValue(games: Array<String>): String {
    var myPrint: Int
    while (true) {
        println("请选择你要出的拳：")
        for ((index, item) in games.withIndex()) {
            println("${index + 1}. $item")
        }
        myPrint =
            try {
                readLine()!!.toInt()
            } catch (e: NumberFormatException) {
                continue
            }
        if (myPrint > 0 && myPrint < games.size + 1) {
            return games[myPrint - 1]
        } else {
            continue
        }

    }

}

fun getRobotValue(games: Array<String>): String {
    return games[(Math.random() * games.size).toInt()]
}