由於Visual Basic中的按揭付款計算中收到「infinity」

我是第一年的編程學生，正在努力製作按揭付款計算器。用戶輸入他們的貸款金額和利率，選擇15或30年的期限長度，他們的每月付款應計算。我認爲數學是正確的，但我認爲我遇到了轉換數據類型的問題。我能夠計算的唯一結果是「無限」。我也試着將所有變量聲明爲雙精度，但沒有區別。由於Visual Basic中的按揭付款計算中收到「infinity」

下面是我遇到的一段代碼，Option Strict On包含在完整的代碼中。任何提示將非常感謝！

Dim decLoanAmount As Decimal 
    Dim decInterestRate As Decimal 
    Dim decFifteen As Decimal = 180D 
    Dim decThirty As Decimal = 360D 
    Dim decNumberOfMonths As Decimal 
    Dim dblPayment As Double 
    Dim decPayment As Decimal 

    ' Did user enter a numeric value? 

    If IsNumeric(txtLoanAmount.Text) And IsNumeric(txtInterestRate.Text) Then 
     decLoanAmount = Convert.ToDecimal(txtLoanAmount.Text) 
     decInterestRate = Convert.ToDecimal(txtInterestRate.Text) 

     ' Is Loan Amount greater than zero? 
     If decLoanAmount > 0 And decInterestRate > 0 Then 
      If radFifteen.Checked = True Then 
       decNumberOfMonths = decFifteen 
      ElseIf radThirty.Checked = True Then 
       decNumberOfMonths = decThirty 
      End If 

      ' Calculate the monthly payments as a double 
      dblPayment = (decLoanAmount * (decInterestRate/12/100) * (1 + (decInterestRate/12/100) _ 
       ^decNumberOfMonths))/((1 + (decInterestRate/12/100)^decNumberOfMonths) - 1) 
      ' Convert double to decimal 
      decPayment = Convert.ToDecimal(decPayment) 
      ' Display monthly payment 
      lblPayment.Text = decPayment.ToString("C2") 

     Else 
      If decLoanAmount < 0 Then 
       MsgBox("Please enter a valid loan amount.", , "Input error") 
      End If 

      If decInterestRate < 0 Then 
       MsgBox("Please enter a valid interest rate.", , "Input error") 
      End If 

     End If 

    Else 
     ' Display error message if user entered a negative value. 
     MsgBox("Please enter a numeric value.", , "Input Error") 
    End If 
End Sub

來源

2014-12-07 SJW

我建議保理出來了一下，檢查值就像你所期望的那樣 - 例如，在計算過程中會重複'（decInterestRate/12/100）'，所以爲什麼不先計算它，然後檢查這個值是否如你所期望的那樣。 – 2014-12-07 21:08:49

此外，'decPayment = Convert.ToDecimal（decPayment）'不會做很多... – 2014-12-07 21:09:59

您不希望人們在這裏爲您編寫和/或調試代碼，對吧？向我們展示一些研究，提供樣本輸入，輸出，更多解釋。假設上面的代碼不在那裏，你認爲你描述的內容足以幫助你嗎？ – Neolisk 2014-12-07 21:48:08

根據Wikipedia formula，您的操作不正確。它應該是這個樣子：

dblPayment = (decLoanAmount * (decInterestRate/(12 * 100)))/(1 - (1 + (decInterestRate/(12 * 100)))^(-decNumberOfMonths))

而且，這條線是怪異

decPayment = Convert.ToDecimal(decPayment)

應該

decPayment = Convert.ToDecimal(dblPayment)

來源

2014-12-08 14:04:31

由於Visual Basic中的按揭付款計算中收到「infinity」

回答

相關問題