List<string> 转string[]

记录下这个功能，也是比较常用的，主要是ToArray方法。

 public static String[] GetAllRuleHref()        {            //IList<Rules> rule = RuleManager.GetAllRule();            List<String> rid = new List<string>();            for (int i = 0; i < rule.Count; i++)            {                Rules rul = rule[i];                rid.Add(rul.RuHref);            }            return rid.ToArray();        }