How can I make this VB code work in C# using the same variable?

Question

I'm trying to figure out how to convert the following sample code to C# using the same implicit define as VB. I know I can define the button and generic control as two objects and make it work, but I would like to use the same variable "ctlHTML" in C# just like VB works. Can someone help on this?

Sub MySub(varInput As String, pnl As Panel)
    Dim ctlHTML = Nothing
    Select Case varInput
        Case "btn"
            ctlHTML = New HtmlButton
        Case "lbl"
            ctlHTML = New HtmlGenericControl()
    End Select
    With ctlHTML
        .Style.Add("font-size", "14px")
    End With
    pnl.Controls.Add(ctlHTML)
End Sub

Answer 1

You won't be able to directly convert the code. You'll have to give your variable a type. The class highest in the inheritance chain that supports all of your members would be HtmlControl:

HtmlControl control = null;
switch(varInput)
{
    case "btn":
        control = new HtmlButton();
        break;
    case "lbl":
        control = new HtmlGenericControl();
        break;
}

if(control != null)
{
    control.Style.Add("font-size", "14px");
    pnl.Controls.Add(control);
}

Answer 2

In order to modify the Style property, the control at minimum needs to be an HtmlControl. So you need to declare the variable ctlHtml as that type.

You should also check to make sure the ctlHtml is properly initialized.

I believe your code should look something like this:

public void MySub(string varInput, Panel pnl)
{
    HtmlControl ctlHtml;
    switch(varInput)
    {
        case "btn":
            ctlHtml = new HtmlButton();
            break;
        case "lbl":
            ctlHtml = new HtmlGenericControl();
            break;
        default:
            ctlHtml = null;
            break;
    }
    if (ctlHtml != null)
    {
        ctlHtml.Style.Add("font-size", "14px");
        pnl.Controls.Add(ctlHtml);
    }
}

Answer 3

Since HtmlGenericControl and HtmlButton both inherit from HtmlControl, you can declare ctlHTML as that type (HtmlControl) and it will work.

See here: http://msdn.microsoft.com/en-us/library/system.web.ui.htmlcontrols.htmlcontrol.aspx