【发布时间】：2016-11-16 16:53:18
【问题描述】：
我目前正在处理一个大学数学项目，该项目要求我创建一个与抵押贷款相关的应用程序。我正在尝试编写 Swift 代码来计算每个月支付的抵押贷款的本金和利息。
我写的代码如下（值得一提的是我对编码很陌生，对Python有一点经验，这都是自学的，欢迎批评！）：
// Declare all variables
// y = periodic interest rate
// n = time left of repayment period (months)
let y = [Float](arrayLiteral: 0.02/12,0.03/12,0.04/12,0.05/12)
let n = [Float](arrayLiteral: 240,180,120,60)
var x = [Float]()
var interest = [Float]()
var T_1 = [Int]()
// Create Array from 0 to 240
for a in 0...240 {
T_1.append(a)
}
// Create Array of all 240 interest values
for a in 0...239 {
if a < 60 {
interest.append(y[0])
var repay = n[0]
x.append(repay)
}
else if a < 120 {
interest.append(y[1])
var repay = n[1]
x.append(repay)
}
else if a < 180 {
interest.append(y[2])
var repay = n[2]
x.append(repay)
}
else {
interest.append(y[3])
var repay = n[3]
x.append(repay)
}
}
print("Interest array:",interest)
// Calculate Each months Principal paid and Interest Paid
func variablerate(P: inout Float) -> [Float] {
var principal = [Float]()
var i_paid = [Float]()
var repayments = [Float]()
var R = Float(0)
let temporaryP = P
i_paid.append(0)
for a in 0...240 {
if (a>0) && (a<240) && (interest[a-1] == interest[a]) {
let ip = P*(1+interest[a-1])-P
i_paid.append(i_paid[a-1] + ip)
P = (1+interest[a-1])*temporaryP
P = P-R
let h = interest[a]
R = (P*h)/(1-pow(1+h,Float(interest.count-a)))
repayments.append(R)
principal.append(round(100*P)/100)
}
else if a==240 || a==241 {
P = P - R
principal.append(round(100*P)/100)
let ip = P*(1+interest[a-1])-P
i_paid.append(i_paid[a-1] + ip)
let h = interest[a-1]
P = P*(1+h)
}
else {
P = P - R
let h = interest[a]
R = (P*h)/(1-pow(1+h,Float(interest.count-a)))
repayments.append(R)
principal.append(round(100*P)/100)
let ip = P*(1+interest[a])-P
i_paid.append(i_paid[a-1] + ip)
P = P*(1+h)
}
}
return i_paid
return principal
}
var z = Float(100000)
print(variablerate(P: &z)) //This is where the error appears
给出的错误是：
错误：执行被中断，原因：EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP,subcode=0x0)。
非常感谢您对此问题的任何帮助或指导！
【问题讨论】：
-
在此之前我遇到了错误，例如未解析的标识符“pow”？
-
@dylan 我的 Swift Playground 上没有出现其他错误。 pow(double, double) 已用于使用幂的表达式。
-
当
a为零时，在已编译的项目中运行代码会在i_paid.append(i_paid[a-1] + ip)处出现“致命错误：索引超出范围”而中止... -
请注意，
return principal永远不会被执行。