桑心啊，List<T>.FindAll()的效率竟然比for循环还差。

自从认识了FindAll()，一般List中查找符合条件的数据项我都用List<T>.Find()或List<T>.FindAll().

代码简洁，自己看了赏心悦目，况且是微软内部的方法，效率应该不会差。

然而，今天心血来潮，写代码测试了一下，确发现FindAll()比For循环效率差了好多，集合比较小的时候这差异就更明显了。

测试代码：

Stopwatch watch = new Stopwatch();
            Random rand = new Random();
            List<int> list = new List<int>();
            //构造一个LIST
            for (int i = 0; i < 100; i++)
            {
                list.Add(rand.Next(10));
            }
            //用FindAll
            watch.Start();
            List<int> resultFindAll = list.FindAll(delegate(int i) { return i == 5; });
            watch.Stop();
            Console.WriteLine("FindAll:" + watch.Elapsed.Ticks);
            Console.WriteLine("resultFindAll:" + resultFindAll.Count);
            //用For循环
            List<int> resultFor = new List<int>();
            watch.Reset();
            watch.Start();
            for (int i = 0; i < list.Count; i++)
            {
                if (list[i] == 5)
                {
                    resultFor.Add(list[i]);
                }
            }
            watch.Stop();
            Console.WriteLine("For:"+watch.Elapsed.Ticks);
            Console.WriteLine("resultFor:" + resultFor.Count);