添加2个文本框的值以在其中一个显示结果 [英] Adding the values of 2 textboxes to display result in one of them

问题描述

在我的表单上，我有2个文本框，分别为 txtsurcharges.text和 txttotal.text。

On my form I have 2 textboxes called 'txtsurcharges.text' and 'txttotal.text'

txttotal从mysql表中检索一个值，但是我想要发生的是，当我在txtsurcharges中输入一个值并在txttotal中显示结果时，该值将被添加。

txttotal retrieves a value from mysql table, but what I want to happen is that this value becomes added to when I type in a value into txtsurcharges and display the result in txttotal.

这是我的txtsurcharges代码：

Here is my code for txtsurcharges:

txtsurcharges.Text = String.Format("£{0}", txtsurcharges.Text)

这是我的txttotal代码：

Here is my code for txttotal:

Private Sub cbxPaymentID_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cbxPaymentID.SelectedIndexChanged
        Dim dss As New DataSet
        If (cbxPaymentID.SelectedIndex <> -1) Then
            Dim daa As New MySqlDataAdapter("SELECT * from payment_details WHERE PaymentID=@PID", _
            objconnection)
            daa.SelectCommand.Parameters.AddWithValue("@PID", Convert.ToInt32(cbxPaymentID.SelectedValue))
            daa.Fill(dss)
            txttotal.Text = dss.Tables(0).Rows(0)("ServicePayment").ToString()

        End If
    End Sub

这是我添加两个值的代码，不起作用：

Here is my code for the addition of the 2 values, which doesn't work:

Private Sub txtsurcharges_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtsurcharges.TextChanged
        Dim c As Integer
        c = Val(txtsurcharges.Text) + Val(txttotal.Text)
        c = txttotal.Text
    End Sub

推荐答案

尝试一下（更新以显示ASPX和VB代码，并带有几个静态值进行测试）

Try this (UPDATED TO SHOW ASPX and VB code with a couple of static values for test)

aspx代码

<asp:TextBox ID="txtsurcharges" runat="server" Text="£5" AutoPostBack="true"></asp:TextBox>
    <asp:TextBox ID="txttotal" runat="server" Text="£5"></asp:TextBox>

vb代码

Private Sub txtsurcharges_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtsurcharges.TextChanged 
    Dim c As Integer 
    c = CInt(txtsurcharges.Text) + CInt(txttotal.Text) 
    txttotal.Text = c
End Sub

您可以

如果我现在将txtsurcharges更改为10，则txttotal将更改为15。

If I now change txtsurcharges to 10 then txttotal will change to 15.

当然，您需要确保只能在txtsurcharges中键入数字。

You will of course need to make sure that only numerics can be typed into txtsurcharges.

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