title: How to get string from url in ASP.NET webforms?
body: <p>I think my tittle is inaccurate. </p>
  
  <p>When a user clicks on a button I need it to do this:</p>
  
  <pre><code>Response.Redirect("Login.aspx?userid=XX");
  </code></pre>
  
  <p>How can I get the <code>"userid?"</code> from <code>?userid.</code> so I can show a page. Like doing <code>"?page=3"</code> and show <code>page 3</code>, in the same page or something.</p>
  
  <p>The Button code is: (just if you need it)</p>
  
  <pre><code>protected void LoginButton_Click(object sender, EventArgs e)
  {
      Response.Redirect("Login.aspx");
  }
  </code></pre>
  
  <p>Thanks a lot! Sorry if I didn't ask it good, and sorry for the bad English.</p>