ASP.NET overwriting cookie

Question

I'm having trouble overwriting the value of a cookie. The first time a user submits a username the cookie stores in the browser fine and is displayed properly. But when the user tries to submit a different user name the page refreshes and the old cookie is still set. Here is my hopefully understandable code, any help is appreciated.

protected void Cookie_Encode(object sender, EventArgs e)
{
        // Encoding username in Base64
        var plainTextBytes = System.Text.Encoding.UTF8.GetBytes(User_box.Text);
        string Encoded_user = System.Convert.ToBase64String(plainTextBytes);

        // Creating and setting the cookie
        HttpCookie myCookie = new HttpCookie("UserSettings");
        myCookie["UserName"] = Encoded_user;
        myCookie.Expires = DateTime.Now.AddDays(7d);
        Response.Cookies.Add(myCookie);

        Response.Redirect(Request.RawUrl);
}

Answer 1

Use DateTime.Now.AddDays(-1) instead of DateTime.Now.AddDays(7d).

protected void Cookie_Encode(object sender, EventArgs e)
{
    // Encoding username in Base64
    var plainTextBytes = System.Text.Encoding.UTF8.GetBytes(User_box.Text);
    string Encoded_user = System.Convert.ToBase64String(plainTextBytes);

    // Creating and setting the cookie
    HttpCookie myCookie = new HttpCookie("UserSettings");
    myCookie["UserName"] = Encoded_user;
    myCookie.Expires = DateTime.Now.AddDays(-1);
    Response.Cookies.Add(myCookie);

    Response.Redirect(Request.RawUrl);
}