public static string BuildPostDataString(NameValueCollection postvars)
{
StringBuilder ret = new StringBuilder();
for (int i = 0; i < postvars.Keys.Count; i++)
{
if (i > 0)
ret.Append("&");
ret.Append(postvars.Keys[i] + "=" + HttpUtility.UrlEncode(postvars[postvars.Keys[i]]));
}
return ret.ToString();
}