無法在類中訪問我的文本框輸入

Question

我是VB新手，在分配課程時遇到了一些麻煩。基本上它應該是一個發票小計 - 找到折扣百分比，並給出實際總額。我似乎無法讓我的課程訪問用戶輸入的文本框，它只是一直返回0。這是一個家庭作業，以及...即時通訊不要求只是一些提示的答案，因爲我真的在虧損，無法弄清楚這一點！

這是我的代碼按鈕單擊事件：

Public Sub btnCalc_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalc.Click 
    'If txbxSubtotal.Text >= 500 Then 
    ' discountpercent = 0.2 
    'ElseIf txbxSubtotal.Text >= 250 And txbxSubtotal.Text < 500 Then 
    ' discountpercent = 0.15 
    'ElseIf txbxSubtotal.Text >= 100 And txbxSubtotal.Text < 250 Then 
    ' discountpercent = 0.1 
    'Else 
    ' discountpercent = 0 
    'End If 
    'discountAmount = txbxSubtotal.Text * discountpercent 
    'total = txbxSubtotal.Text - discountAmount 
    Dim myinvoice As New Getinvoice 
    myinvoice.setAmount(total = Convert.ToDecimal(txbxSubtotal.Text)) 
    total = txbxSubtotal.Text 
    MessageBox.Show(myinvoice.getdiscountAmount) 
    MessageBox.Show(myinvoice.getAmount) 
End Sub 
End Class 

，這是我的類中的代碼：

Public Class Getinvoice 

    Private subtotal As Decimal 
    Private discount As Decimal 
    Private discountAmount As Decimal 
    Private discountpercent As Decimal 
    Private amount As Decimal 

    Public Sub setAmount(ByVal total As Decimal) 
     amount = total 
    End Sub 

    Public Function getAmount() 
     Return amount 
    End Function 

    Public Sub setdiscountPercent(ByVal discPcnt As Decimal) 
     discountAmount = discPcnt 

     If amount >= 500 Then 
      discountpercent = 0.2 
     ElseIf amount >= 250 And amount < 500 Then 
      discountpercent = 0.15 
     ElseIf amount >= 100 And amount < 250 Then 
      discountpercent = 0.1 
     Else 
      discountpercent = 0 
     End If 
    End Sub 

    Public Function getdiscountAmount() 
     Return discountpercent 
    End Function 

End Class 

Answer 1

你從來沒有叫

setdiscountPercent(ByVal discPcnt As Decimal) 

所以discountpercent從未設置。這就是爲什麼你得到0;

編輯：

Public Sub setdiscountPercent(ByVal discPcnt As Decimal) 
    discountAmount = discPcnt 

    If amount >= 500 Then 
     discountpercent = 0.2 
    ElseIf amount >= 250 And amount < 500 Then 
     discountpercent = 0.15 
    ElseIf amount >= 100 And amount < 250 Then 
     discountpercent = 0.1 
    Else 
     discountpercent = 0 
    End If 
End Sub 

這是你的代碼。就拿你設置這個方法discountAmount = discPcnt

內但是當你的代碼已經發布，你永遠不會調用setdiscountPercent(ByVal discPcnt As Decimal)

所以discountAmount和discountpercent永遠不會設置爲任意值一看。這是你的問題來自哪裏。