How to get string from url in ASP.NET webforms?

Question

I think my tittle is inaccurate.

When a user clicks on a button I need it to do this:

Response.Redirect("Login.aspx?userid=XX");

How can I get the "userid?" from ?userid. so I can show a page. Like doing "?page=3" and show page 3, in the same page or something.

The Button code is: (just if you need it)

protected void LoginButton_Click(object sender, EventArgs e)
{
    Response.Redirect("Login.aspx");
}

Thanks a lot! Sorry if I didn't ask it good, and sorry for the bad English.

Answer 1

Use Request.QueryString:

First Page Sends them another page with their user id in the url:

Response.Redirect("AfterLogIn.aspx?userid=23");

You then Read it using the below code:

var g = Request.QueryString["userid"] //this value should be 23 now

You could then use this g variable to do any amount of custom things (Hide panels, show controls, etc.)