kotlin简单四则运算计算器_使用kotlin语言编写一个四则运算式子生成器

fun main() {
    println("----pleass pass biaodashi ----")
    val input:String? = readLine()
    try {
        input?.let{
            val ret = caculate(it)
            println("${input} = ${ret}")
            println("are you y/n also use?")
            val cmd:String? = readLine()
            cmd?.let {
                if (it.equals("n")){
                    System.exit(-1)
                }else{
                    return main()
                }
            }
        }
    }catch (ex:Exception){
        ex.printStackTrace()
    }
}
 
fun caculate(input:String): String {
    if (input.contains("+")) {
        var nums = input.trim().split("+")
        return operate(nums[0].toDouble(),nums[1].toDouble(),"+").toString()
    }else if (input.contains("-")){
        var nums = input.trim().split("-")
        return operate(nums[0].toDouble(),nums[1].toDouble(),"-").toString()
    }else if (input.contains("/")){
        var nums = input.trim().split("/")
        return operate(nums[0].toDouble(),nums[1].toDouble(),"/").toString()
    }else if (input.contains("*")){
        var nums = input.trim().split("*")
        return operate(nums[0].toDouble(),nums[1].toDouble(),"*").toString()
    }else {
        return "you input biaodashi error"
    }
}
fun operate(num_1:Double,num_2: Double,symbol:String):Double{
    return when(symbol){
        "+" -> num_1 + num_2
        "-" -> num_1 - num_2
        "*" -> num_1 * num_2
        "/" -> num_1 / num_2
        else -> 0.0
    }
}

代码实现效果：