Question

我正在尝试制作月度贷款支付计算器这是代码：

import UIKit

class monthlypayment: UIViewController {



@IBOutlet weak var loanamounttextfield: UITextField!
@IBOutlet weak var numberofmonthstextfield: UITextField!
@IBOutlet weak var loanpercentagetextfield: UITextField!
@IBOutlet weak var answerlabel: UILabel!

@IBAction func calculate(sender: AnyObject) {
    var loanamounttext = loanamounttextfield.text
    var loanamount:Double! = Double((loanamounttext as NSString).doubleValue)
    var loanpercentage = loanpercentagetextfield.text
    var loanpercentagedouble:Double! = Double((loanpercentage as NSString).doubleValue)
    var numbrofmonths = numberofmonthstextfield.text
    var numberofmonths:Double! = Double((numbrofmonths as NSString).doubleValue)
    var rate = loanpercentagedouble/1200
    var monthlypayment:Double = rate+(rate/(1.0+rate)^numberofmonths)-1.0*loanamount
    }
}

我在这里收到错误

        var rate = loanpercentagedouble/1200
        var monthlypayment:Double = rate+  (rate/(1.0+rate)^numberofmonths)-1.0*loanamount

如你所见，numberofmonths和loanamount是双倍的

但我收到错误：找不到接受提供的参数的“+”

Answer 1

在Swift中^是XOR运算符（返回各种Ints）而不是指数，你想使用pow(num, power)函数

var monthlypayment = rate + pow(rate / (1.0 + rate), numberofmonths) - 1.0 * loan amount

或者，您可以定义自定义运算符

infix operator ** { associativity left precedence 160 }

func ** (left: Double, right: Double) -> Double {
    return pow(left, right)
}

并将您的代码重写为更易读的

var monthlypayment = rate + (rate / (1.0 + rate)) ** numberofmonths - 1.0 * loanamount

找不到接受提供的参数的'+'

1 个答案: