for/foreach/linq执行效率测试

最新推荐文章于 2020-12-22 16:47:53 发布

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最新推荐文章于 2020-12-22 16:47:53 发布

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原文链接：http://www.cnblogs.com/weapon/archive/2013/05/18/3084801.html

本文通过测试LINQ、foreach、for及while循环在C#中的执行效率，对比不同循环方式查找特定元素的速度差异。测试中使用了一个包含一万个元素的整数列表，并进行了多次迭代以获取平均耗时。

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测试代码

             private static void Test1(int count)
        {
            int s;
            List<int> list = new List<int>();
            for (int i = 0; i < 10000; i++)
            {
                list.Add(i);
            }
            Console.WriteLine("这是测试for/linq/foreach效率开始");
            DateTime d1 = DateTime.Now;
            for (int i = 0; i < count; i++)
            {
                var roleQuery = from r in list
                                where r == 3500
                                select r;
                foreach (var role in roleQuery)
                {
                    s = role;
                }
                Console.WriteLine("测试Linq第" + i +"次");
            }
            DateTime d2 = DateTime.Now;
            DateTime d3 = DateTime.Now;
            for (int c = 0; c < count; c++)
            {
                foreach (int role in list)
                {
                    if (role == 350)
                    {
                        s = role;
                    }
                }
                Console.WriteLine("测试foreach第" + c + "次");
            }
            DateTime d4 = DateTime.Now;
            DateTime d5 = DateTime.Now;
            for (int c = 0; c < count; c++)
            {
                for (int i = 0; i < list.Count; i++)
                {
                    if (list[i] == 350)
                    {
                        s = list[i];
                    }
                }
                Console.WriteLine("测试for第" + c + "次");
            }
            DateTime d6 = DateTime.Now;
            DateTime d7 = DateTime.Now;
            for (int c = 0; c < count; c++)
            {
                int i=0;
                while ( i<list.Count)
                {
                    if (list[i] == 350)
                    {
                        s = list[i];
                    }
                    i++;
                }
                Console.WriteLine("测试while第" + c + "次");
            }
            DateTime d8 = DateTime.Now;
            Console.WriteLine("linq测试时长为：" + (d2 - d1).ToString());
            Console.WriteLine("foreach测试时长为：" + (d4 - d3).ToString());
            Console.WriteLine("for测试时长为：" + (d6 - d5).ToString());
            Console.WriteLine("while测试时长为：" + (d8 - d7).ToString());
            Console.Read();
        } 
    

调用代码

             static void Main(string[] args)
        {
            //NewMethod();
            int count = 100000000;
            Test1(count / 1000); //太大了时间太长
            //Test2(count);
        } 
    