Question

I’m new to Visual Basic.
I have a little program look like this.
https://www.dropbox.com/s/xr44pxp3n79atkk/wall.png

It will calculate the total area by adding up all wall area.

Public Sub btnWallAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnWallAdd.Click
    FlowLayoutPanel1.Controls.Clear()
    FlowLayoutPanel1.AutoScroll = True

    For i As Integer = 1 To Val(txtWallNo.Text)
        Dim Width As New TextBox()
        Dim Height As New TextBox()

        Width.Name = "Width" & i
        Width.Text = Width.Name
        Height.Name = "Height" & i
        Height.Text = Height.Name

        FlowLayoutPanel1.Controls.Add(Width)
        FlowLayoutPanel1.Controls.Add(Height)

    Next
End Sub

I have successfully create dynamic textbox base on the number entered by user but I don’t know how to get values from those textbox an add them up. Please teach me how do it. Thank you very much!
Sorry for my English!

Answer 1

You can access the controls by name, like this:

Dim txtWidth As TextBox = FlowLayoutPanel1.Controls.Item("Width" & i)

Or, if you have option strict turned on, you need to be explicit about the type conversions:

Dim txtWidth As TextBox = CType(FlowLayoutPanel1.Controls.Item("Width" & i.ToString()), TextBox)

For instance, to add up the area on all the walls, you could do something like this:

Public Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click
    Dim totalArea As Decimal = 0
    For i As Integer = 1 To Val(txtWallNo.Text)
        Dim txtWidth As TextBox = CType(FlowLayoutPanel1.Controls.Item("Width" & i.ToString()), TextBox)
        Dim txtHeight As TextBox = CType(FlowLayoutPanel1.Controls.Item("Height" & i.ToString()), TextBox)
        totalArea = totalArea + (Decimal.Parse(txtHeight.Text) * Decimal.Parse(txtWidth.Text))
    Next
    lblResult.Text = totalArea.ToString()
End Sub