Kotlin 错误：未解析的引用：roundToInt

我试图使用

roundToInt（）

将双精度值转换为四舍五入整数，但我得到了

未解析的引用

异常

我正在经历官方的考验，但仍然没有运气

代码：

fun solve(meal_cost: Double, tip_percent: Int, tax_percent: Int): Unit {
    var tip = (meal_cost *tip_percent)/100
    var tax = (meal_cost *tax_percent)/100
    var totalCost = (tip+tax+meal_cost).roundToInt()

    System.out.println("The total cost is "+totalCost+".")
}

Solution.kt:25:41: error: unresolved reference: roundToInt
var totalCost = (tip+tax+meal_cost).roundToInt()
                                    ^   

编辑1:

fun solve(meal_cost: Double, tip_percent: Int, tax_percent: Int): Unit {
    var tip = (meal_cost *tip_percent)/100
    var tax = (meal_cost *tax_percent)/100
    var totalCost = (tip+tax+meal_cost).roundToInt()

    System.out.println("The total cost is "+totalCost+".")
}

Solution.kt:25:41: error: unresolved reference: roundToInt
var totalCost = (tip+tax+meal_cost).roundToInt()
                                    ^   

错误日志：

fun solve(meal_cost: Double, tip_percent: Int, tax_percent: Int): Unit {
    var tip = (meal_cost *tip_percent)/100
    var tax = (meal_cost *tax_percent)/100
    var totalCost = (tip+tax+meal_cost).roundToInt()

    System.out.println("The total cost is "+totalCost+".")
}

Solution.kt:25:41: error: unresolved reference: roundToInt
var totalCost = (tip+tax+meal_cost).roundToInt()
                                    ^   

---

您需要导入此函数

import kotlin.math.roundToInt

---

roundToInt（）

是由

math

包提供的一个扩展函数，而不是

Double

的成员函数，因为

餐费

，

旅行百分比

和

税收百分比

也是整数。这意味着

totalCost

的类型为

Int

<未为

Int

定义code>roundToInt（）

将您的

/100

更改为

/100.0

，以便除以一个双精度数，结果也将变成一个双精度数

var tip = (meal_cost *tip_percent)/100.0 // divide by double to make the result a double
var tax = (meal_cost *tax_percent)/100.0
var totalCost = (tip+tax+meal_cost).roundToInt() //Works now.
System.out.println("The total cost is "+totalCost+".") 

---

餐费、小费和税金的百分比是什么？如果它们是

Int

小费和税金也是

Int

。试一试

/100.0

餐费双变量平均成本是双变量