private bool checkMessage(List<QQMessage> messages, int fromIndex, QQMessage checkingMsg, out int index) { for (index = fromIndex; index < messages.Count; index++) { var message = messages[index]; if (checkingMsg.date < message.date || (checkingMsg.date == message.date && checkingMsg.time < message.time)) { break; } else if (checkingMsg.Equals(message)) { return false; } } return true; }