Question

我是VB的新手，我正在尝试制作一个计算器来计算售出的门票数量。我需要在dblAdultTicketsSold和dblChildTicketsSold中输入小数。我现在有限制，不允许负数，只允许数字。我感谢任何帮助。

Private Sub Button1_Click（sender As Object，e As EventArgs）处理btnCalculate.Click

    ''Declare local variables
    Dim decAdultPricePerTicket As Decimal
    Dim dblAdultTicketsSold As Double
    Dim decGrossAdultSalesTotal As Decimal
    Dim decChildPricePerTicket As Decimal
    Dim dblChildTicketsSold As Double
    Dim decGrossChildSalesTotal As Decimal
    Dim decGrossSalesTotal As Decimal
    Dim decNetAdultSalesTotal As Decimal
    Dim decNetChildSalesTotal As Decimal
    Dim decNetTotalSales As Decimal




    'Put backcolor back to white after it turns yellow
    txtAdultPricePerTicket.BackColor = Color.White
    txtAdultTicketsSold.BackColor = Color.White
    txtChildPricePerTicket.BackColor = Color.White
    txtChildTicketsSold.BackColor = Color.White


    ' Validate Inputs

    Try

        'Validate Adult Price Per Ticket is positive numeric
        If IsNumeric(txtAdultPricePerTicket.Text) Then
            decAdultPricePerTicket = CDec(txtAdultPricePerTicket.Text)
        Else
            MessageBox.Show("Please enter a positive numeric value for Price per Adult Ticket.")
            txtAdultPricePerTicket.Focus()
            txtAdultPricePerTicket.BackColor = Color.Yellow
            Exit Sub
        End If

        If decAdultPricePerTicket < 1 Then
            MessageBox.Show("Please enter a positive numeric value for Price per Adult Ticket.")
            txtAdultPricePerTicket.Focus()
            txtAdultPricePerTicket.BackColor = Color.Yellow
            Exit Sub
        End If

        'Validate amount of Adult tickets with positive numeric
        If IsNumeric(txtAdultTicketsSold.Text) Then
            dblAdultTicketsSold = CDbl(txtAdultTicketsSold.Text)
        Else
            MessageBox.Show("Please enter a positive numeric value for amount for Adult Tickets Sold.")
            txtAdultTicketsSold.Focus()
            txtAdultTicketsSold.BackColor = Color.Yellow
            Exit Sub
        End If

        If dblAdultTicketsSold < 1 Then
            MessageBox.Show("Please enter a positive numeric value for amount for Adult Tickets Sold.")
            txtAdultTicketsSold.Focus()
            txtAdultTicketsSold.BackColor = Color.Yellow
            Exit Sub
        End If


        'Validate Child Price per Tickets is a positive numeric

        If IsNumeric(txtChildPricePerTicket.Text) Then
            decChildPricePerTicket = CDec(txtChildPricePerTicket.Text)
        Else
            MessageBox.Show("Please enter a positive numeric value for Price per Child Ticket.")
            txtChildPricePerTicket.Focus()
            txtChildPricePerTicket.BackColor = Color.Yellow
            Exit Sub
        End If

        If decChildPricePerTicket < 1 Then
            MessageBox.Show("Please enter a positive numeric value for Price per Child Ticket.")
            txtChildPricePerTicket.Focus()
            txtChildPricePerTicket.BackColor = Color.Yellow
            Exit Sub
        End If


        'Validate amount of child tickets with positive numeric

        If IsNumeric(txtChildTicketsSold.Text) Then
            dblChildTicketsSold = CDbl(txtChildTicketsSold.Text)
        Else
            MessageBox.Show("Please enter a positive numeric value for amount of  Child Tickets.")
            txtChildTicketsSold.Focus()
            txtChildTicketsSold.BackColor = Color.Yellow
            Exit Sub
        End If

        If dblChildTicketsSold < 0 Then
            MessageBox.Show("Please enter a positive numeric value for amount of Child Tickets.")
            txtChildTicketsSold.Focus()
            txtChildTicketsSold.BackColor = Color.Yellow
            Exit Sub
        End If






        'Calculate and display GrossAdultSalesTotal

        decGrossAdultSalesTotal = CDec(CDec(txtAdultPricePerTicket.Text) * CDbl(txtAdultTicketsSold.Text))
        lblGrossAdultSalesTotal.Text = decGrossAdultSalesTotal.ToString("c")

        'Calculate and display GrossChildSalesTotal
        decGrossChildSalesTotal = CDec(CDec(txtChildPricePerTicket.Text) * CDbl(txtChildTicketsSold.Text))
        lblGrossChildSalesTotal.Text = decGrossChildSalesTotal.ToString("c")

        'Calculate total gross sales
        decGrossSalesTotal = decGrossAdultSalesTotal + decGrossChildSalesTotal
        lblGrossTotalSales.Text = decGrossSalesTotal.ToString("c")

        'Calculate Net adult ticket sales 20%
        decNetAdultSalesTotal = CDec(0.2 * decGrossAdultSalesTotal)
        lblNetAdultSalesTotal.Text = decNetAdultSalesTotal.ToString("c")

        'Calculate Net child ticket sales 20%
        decNetChildSalesTotal = CDec(0.2 * decGrossChildSalesTotal)
        lblNetChildSalesTotal.Text = decNetChildSalesTotal.ToString("c")

        'Calculate Net total of adult and child tickets
        decNetTotalSales = decNetChildSalesTotal + decNetAdultSalesTotal
        lblNetTotalSales.Text = decNetTotalSales.ToString("c")

    Catch
        'Error Message
        MessageBox.Show("All inputs must be valid positive numeric values")
    End Try


End Sub

Answer 1

如果您使用NumericUpDown，您可以将所有这些规则添加到控件...默认情况下它已经禁止字母字符，如果最小值设置为零并且增量设置为1，则它将禁止使用负数和十进制数字。如果您决定坚持使用文本框，我总是倾向于限制用户输入的内容，而不是在用户点击“提交”时将其显示错误消息。按钮或其他什么，你可以模仿NumericUpDown的文本过滤器，如下所示：

'Imports System.Text.RegularExpressions

Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
    TextBox1.Text = Regex.Replace(TextBox1.Text, "[^0-9]", "")
    TextBox1.Select(TextBox1.Text.Length, 0)
End Sub

编辑：如果您需要用户在尝试输入十进制数时收到提醒，那么您可以尝试这样做：

Private Sub txtAdultPricePerTicket_TextChanged(sender As Object, e As EventArgs) Handles txtAdultPricePerTicket.TextChanged
    If txtAdultPricePerTicket.Text.Contains(".") Then
        MessageBox.Show("You can't buy a piece of a ticket dummy") '(may want to replace message text)
        txtAdultPricePerTicket.BackColor = Color.Yellow
        txtAdultPricePerTicket.Focus()
        txtAdultPricePerTicket.Select(txtAdultPricePerTicket.Text.IndexOf("."), 1)
    End If
End Sub

它将显示错误消息并突出显示小数，以便他们可以更改

Answer 2

当使用键盘按下时，这将覆盖.字符。

 Private Sub tbKeyPress(sender As Object, e As KeyPressEventArgs) Handles dblAdultTicketsSold.KeyPress, dblChildTicketsSold.KeyPress
       If e.KeyChar = "." Then
            e.Handled = True
       End If
    End Sub

如何在VB中保留文本框输入的小数

2 个答案: