尝试在Swift Playground中打印功能时出现EXC_BAD_INSTRUCTION错误

Question

我目前正在研究一个大学数学项目，该项目要求我创建与抵押贷款有关的应用程序。我试图编写Swift代码来计算抵押贷款每月支付的本金和利息。

我写的代码如下（值得一提的我很新用与Python的一点经验的编码，这都是自学的，所以任何批评是值得欢迎的！）：

// 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 

的给定的错误是：

error: Execution was interrupted, reason: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP,subcode=0x0).

在这个问题上的任何帮助或指导，将大规模感激！

Answer 1

坠机原因是指数超出范围。

你越来越指数超出范围的异常，因为在代码中，你正在运行一个循环从0到240，并从局部变量一个在第一次迭代一个减去1，因此将包含0和0减去1将给予负面指数。

这里是错误

要在0 ... 240 {
如果（a> 0时）& &（一个< 240）& &（兴趣[A-1] ==兴趣并[a]）

下面码与校正

// 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 1...240 { // Code corrected now loop go from 1 to 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))")