Programming C#, Second Edition

Adding Controls

You can add server-side controls to a Web Form in two ways: manually (by writing HTML into the HTML page), or by dragging controls from the toolbox to the Design page. For example, suppose you want to use buttons to let the user choose one of three Shippers provided in the Northwinds database. You could write the following HTML into the <form> element in the HTML window:

<asp:RadioButton GroupName="Shipper" id="Airborne" 
    text = "Airborne Express" Checked="True" runat="server">
</asp:RadioButton>
<asp:RadioButton GroupName="Shipper" id="UPS" 
    text = "United Parcel Service" runat="server">
</asp:RadioButton>
<asp:RadioButton GroupName="Shipper" id="Federal" 
    text = "Federal Express" runat="server">
</asp:RadioButton>

The asp tags declare server-side ASP.NET controls that are replaced with normal HTML when the server processes the page. When you run the application, the browser displays three radio buttons in a button group; pressing one will deselect the others.

You can create the same effect more easily by dragging three buttons from the Visual Studio toolbox onto the Form, as illustrated in Figure 15-3.

Figure 15-3. Dragging buttons onto the Web Form

You can add controls to a page in one of two modes. The default mode is GridLayout . When you add controls in GridLayout, they are arranged in the browser using absolute positioning (x and y coordinates).

The alternative mode ...