Before you can use cookies, you should import the System.Net namespace so you can easily work with the appropriate types:
Cookies are fairly easy to use. Both the Request and Response objects (which are provided through Page properties) provide a Cookies collection. The important trick to remember is that you retrieve cookies from the Request object, and you set cookies using the Response object.
To set a cookie, just create a new HttpCookie object. You can then fill it with string information (using the familiar dictionary pattern) and attach it to the current web response:
// Create the cookie object.
HttpCookie cookie = new HttpCookie("Preferences");
// Set a value in it.
cookie["LanguagePref"] = "English";
// Add another value.
cookie["Country"] = "US";
// Add it to the current web response.
Response.Cookies.Add(cookie);
A cookie added in this way will persist until the user closes the browser and will be sent with every request. To create a longer-lived cookie, you can set an expiration date:
// This cookie lives for one year.
cookie.Expires = DateTime.Now.AddYears(1);
You retrieve cookies by cookie name using the Request.Cookies collection:
HttpCookie cookie = Request.Cookies["Preferences"];
// Check to see whether a cookie was found with this name.
// This is a good precaution to take,
// because the user could disable cookies,
// in which case the cookie will not exist.
string language;
if (cookie != null)
{
language = cookie["LanguagePref"];
}
The only way to remove a cookie is by replacing it with a cookie that has an expiration date that has already passed. This code demonstrates the technique:
HttpCookie cookie = new HttpCookie("Preferences");
cookie.Expires = DateTime.Now.AddDays(-1);
Response.Cookies.Add(cookie);
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