Kotlin基础通关之字符串与数字类型

    val str = "abc"
    val str2 = StringBuffer("abc").toString()
    println(str.equals(str2))//true
    println(str == str2)//true
    println(str === str2)//false

    val hello = "Hello world!"
    val sub = hello.substring(0 until 5)
    val sub2 = hello.substring(0, 5)
    println(sub)//hello
    println(sub2)//hello

    val names = "XiaoHua,HanMei,LiLei"
    val data:List<String> = names.split(",")
    val(first:String,second:String,third:String) = names.split(",")
    for(item in data){
        print(item)
    }
    println("$first $second $third")

   val hello = "Hello World!"
    val h2 = hello.replace(Regex("o")) {
        when (it.value) {
            "o" -> "0"
            else -> it.value
        }
    }
    println(h2)

    val hello = "Hello World!"
    hello.forEach { char->
        println(char)
    }
    hello.forEach {
        println(it)
    }

    val pi = "3.14"
    //这种发生就会抛出异常NumberFormatException
    val num = pi.toInt()
    //这个返回null
    val num2 = pi.toIntOrNull()
    println(num2)

    val pi = "%.2f".format(3.1415926)
    println(pi)

    //损失精度
    println(3.5415.toInt())
    //四舍五入
    println(3.5415.roundToInt())