How can I create persistent cookies in ASP.NET?

Here’s how you can do that.

Writing the persistent cookie.

//create a cookie
HttpCookie myCookie = new HttpCookie("myCookie");

//Add key-values in the cookie
myCookie.Values.Add("userid", objUser.id.ToString());

//set cookie expiry date-time. Made it to last for next 12 hours.
myCookie.Expires = DateTime.Now.AddHours(12);

//Most important, write the cookie to client.
Response.Cookies.Add(myCookie);

Reading the persistent cookie.

//Assuming user comes back after several hours. several < 12.
//Read the cookie from Request.
HttpCookie myCookie = Request.Cookies["myCookie"];
if (myCookie == null)
{
    //No cookie found or cookie expired.
    //Handle the situation here, Redirect the user or simply return;
}

//ok - cookie is found.
//Gracefully check if the cookie has the key-value as expected.
if (!string.IsNullOrEmpty(myCookie.Values["userid"]))
{
    string userId = myCookie.Values["userid"].ToString();
    //Yes userId is found. Mission accomplished.
}

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