Beginning Web Development, Silverlight, and ASP.NET AJAX

CHAPTER 3 ■ WEB FORMS WITH ASP.NET 51
if (IsPostBack)
{
string strOperation = Request.Form["optOperation"];
int nF = 0;
Int32.TryParse(txtFirst.Text, out nF);
int nS = 0;
Int32.TryParse(txtSecond.Text, out nS);
int nR = 0;
if (strOperation == "Add")
nR = nF + nS;
else
nR = nF - nS;
litResult.Text = nR.ToString();
}
}
}
Now when you type the values into the text boxes and click the submit button, the
server will return the response and—thanks to view state—maintain the value of the text
boxes.
Also, as ASP.NET generates client-side code, you will have buttons rendered
within the browser anyway! Take a look at the resulting HTML in your browser, and you’ll
see something like Listing 3-9.
Listing 3-9. Viewing the Source Code of the Page in the Browser
Untitled Page