Creating Error Log in ASP.NET

public void WriteError([System.Runtime.InteropServices.OptionalAttribute, System.Runtime.InteropServices.DefaultParameterValueAttribute("")]  
string ErrorNumber, [System.Runtime.InteropServices.OptionalAttribute, System.Runtime.InteropServices.DefaultParameterValueAttribute("")] 
string ErrorMessage, [System.Runtime.InteropServices.OptionalAttribute, System.Runtime.InteropServices.DefaultParameterValueAttribute("")] 
string ErrorSource, [System.Runtime.InteropServices.OptionalAttribute, System.Runtime.InteropServices.DefaultParameterValueAttribute("")] 
string ErrorStackTrace)

string path = "~/Error/" + DateTime.Today.ToString("dd-MM-yyyy") + ".txt";
if (!File.Exists(System.Web.HttpContext.Current.Server.MapPath(path)))
{
    File.Create(System.Web.HttpContext.Current.Server.MapPath(path)).Close();
}

using (StreamWriter w = File.AppendText(System.Web.HttpContext.Current.Server.MapPath(path)))
{
    w.Write("@" + "Log Entry : ");
    w.WriteLine("{0} {1}", DateTime.Now.ToLongTimeString(), DateTime.Now.ToLongDateString());
    w.WriteLine("Error# :{0}", ErrorNumber);
    w.WriteLine("Message :{0}", ErrorMessage);
    w.WriteLine("Source :{0}", ErrorSource);
    w.WriteLine("StackTrace :{0}", ErrorStackTrace);
    w.Flush();
    w.Close();
}