Vb.net 我的错误捕获功能有什么问题？

我有一个购买衬衫的程序，我正在更改它，以便通过一个函数进行错误捕获，因此我删除了以前的错误捕获，创建了该函数，并进行了尝试。但在某个地方我一定是搞砸了，因为它不能正常工作。我一步一步地跟着我班上的视频指南，但我找不到哪里出错了。我已经想了好几个小时了，但还是一无所获。任何帮助都将不胜感激。发生的情况是，当我单击“计算”或“下一次销售”时，它将始终显示我的错误消息。请输入一个有效数字，我已尝试输入0、1、25、50、51、55和5a。它应该给我一个5a的错误消息，说请输入一个有效的数字，因为它不是数字。它应该会给我错误信息，请输入0、51和55的1到50之间的数字。我甚至无法让那个错误消息起作用，因为我输入的每个数字都给出了“请输入一个有效的数字”错误消息。我哪里出错了？请帮我找出错误

以下是函数：

    Private Function CheckTextBox(ByVal TextBoxName As TextBox, ByVal Min As Single, ByVal Max As Single, ByVal IntCheck As Boolean) As Boolean

    If Not IsNumeric(TextBoxName) Then
        MessageBox.Show("Please enter a valid number", "Error", MessageBoxButtons.OK)
        TextBoxName.Text = ""
        TextBoxName.Focus()
        Exit Function
    End If

    If Val(TextBoxName.Text) < Min Or Val(TextBoxName.Text) > Max Then
        MessageBox.Show("Please enter a number from " & Min & " to " & Max, "Error", MessageBoxButtons.OK)
        TextBoxName.Text = ""
        TextBoxName.Focus()
        Exit Function
    End If

    If IntCheck Then
        If Val(TextBoxName.Text) <> Int(TextBoxName.Text) Then
            MessageBox.Show("Please enter a whole number", "Error", MessageBoxButtons.OK)
            TextBoxName.Text = ""
            TextBoxName.Focus()
            Exit Function
        End If
    End If

    Return True

End Function

下面是“下一项”按钮的代码：

    Private Sub btnNextItem_Click(Sender As Object, e As EventArgs) Handles btnNextItem.Click
    'Local Variable Declaration Section
    Dim sngSalesTax As Single
    Dim intQuantity As Integer
    Dim sngItemTotal As Single
    'Data Input Section

    If CheckTextBox(txtQuantity, 1, 50, True) = False Then 'Uses the function to error trap exits sub if functions returns as false
        Exit Sub
    End If

    intQuantity = CInt(txtQuantity.Text)

        'Calculation Section
        sngItemTotal = msngItemPrice * intQuantity 'Calculates item total
        msngSubtotal += sngItemTotal     'Calculates the subtotal
        sngSalesTax = msngSubtotal * csngSalesTaxRate    'Calculates Sales Tax based on the sales tax rate constant
        'Output section
        lblShowShippingCost.Text = ""
        lblShowOrderTotal.Text = ""
        lblShowSubTotal.Text = FormatCurrency(msngSubtotal)  'Displays the Sub Total
        lblShowSalesTax.Text = FormatCurrency(sngSalesTax)  'Displays the Sales Tax
End Sub

---

函数中的第一个If语句应该是If Not IsNumericTextBoxName.Text Then。虽然您在其他语句中包含了.Text，但您仍保留了它。您是否与此问题的提问者属于同一类：？在您的CheckTextBox函数中，您还应将所有出现的Exit函数替换为Return False。

    Private Sub btnNextItem_Click(Sender As Object, e As EventArgs) Handles btnNextItem.Click
    'Local Variable Declaration Section
    Dim sngSalesTax As Single
    Dim intQuantity As Integer
    Dim sngItemTotal As Single
    'Data Input Section

    If CheckTextBox(txtQuantity, 1, 50, True) = False Then 'Uses the function to error trap exits sub if functions returns as false
        Exit Sub
    End If

    intQuantity = CInt(txtQuantity.Text)

        'Calculation Section
        sngItemTotal = msngItemPrice * intQuantity 'Calculates item total
        msngSubtotal += sngItemTotal     'Calculates the subtotal
        sngSalesTax = msngSubtotal * csngSalesTaxRate    'Calculates Sales Tax based on the sales tax rate constant
        'Output section
        lblShowShippingCost.Text = ""
        lblShowOrderTotal.Text = ""
        lblShowSubTotal.Text = FormatCurrency(msngSubtotal)  'Displays the Sub Total
        lblShowSalesTax.Text = FormatCurrency(sngSalesTax)  'Displays the Sales Tax
End Sub