C# List<>与Array性能比较

C# List<>与Array性能比较

    在.net framework 2.0之前，数组表示可以用Array 和集合类 ArrayList 表示，2.0后，.net 引进了泛型的概念List<>，那么我们的选择就多了一种。

   2.0引进泛型其本意是减少类型的装箱拆箱所带来的性能消耗。

   比如;

   private void CompareTo<T>(List<T> list)

   {

     ....

   }

  这里的List<T>就是泛型，调用时我不知道要传入什么类型，有可能是int,string或class.

 

   今天主要讨论的是在类型确定的情况下，哪种性能高一些，ArrayList就不用考虑了，它肯定是最慢的，它只能add object type的.这里主要讨论List<>和Array的性能：

   先看string的情况：

        static void Main(string[] args)

        {

            const int COUNT=1000;

            string[] array = new string[COUNT];

            List<string> list = new List<string>();

            Console.WriteLine("the count is:{0}",COUNT);

           

            Console.Write("the value of Total for array:");

            Stopwatch stopWatch = new Stopwatch();

            stopWatch.Start();

           

            for (int i = 0; i < COUNT; i++)

            {

                array[i] = i.ToString(); ;

            }

           

            int theArrayTotal = 0;

            for (int i = 0; i < COUNT; i++)

            {

                //theArrayTotal += array[i];

               

            }

            stopWatch.Stop();

            Console.Write(theArrayTotal);

            Console.WriteLine();

            Console.Write("array init time:");

 

            Console.Write(stopWatch.ElapsedMilliseconds.ToString());

            stopWatch.Reset();

            stopWatch.Start();

            Console.WriteLine();

           

            for (int i = 0; i < COUNT; i++)

            {

                list.Add(i.ToString()) ;

            }

            int theListTotal = 0;

            foreach (string v in list)

            {

                //theListTotal += v;

            }

            stopWatch.Stop();

            Console.WriteLine("the value of Total for list:{0}", theListTotal);

            Console.Write("list init time:");

            Console.Write(stopWatch.ElapsedMilliseconds.ToString());

            stopWatch.Reset();

            Console.Read();

   }

  当COUNT=1000时，两者看不出差别，用的time都是0

  当COUNT=10000时，也没什么区别

  当COUNT=100000时，

 

the count is:100000

the value of Total for array:0

array init time:16

the value of Total for list:0

list init time:21

Aarry 比List快了5

 

当COUNT=1000000时

 

the count is:1000000

the value of Total for array:0

array init time:296

the value of Total for list:0

list init time:320

 

 Arry比List快了24

 

 当string时，Arry是要比List快

 

 当用int类时：

        static void Main(string[] args)

        {

            const int COUNT=100000;

            int[] array = new int[COUNT];

            List<int> list = new List<int>();

            Console.WriteLine("the count is:{0}",COUNT);

           

            Console.Write("the value of Total for array:");

            Stopwatch stopWatch = new Stopwatch();

            stopWatch.Start();

           

            for (int i = 0; i < COUNT; i++)

            {

                array[i] = i;

            }

           

            int theArrayTotal = 0;

            for (int i = 0; i < COUNT; i++)

            {

                //theArrayTotal += array[i];

               

            }

            stopWatch.Stop();

            Console.Write(theArrayTotal);

            Console.WriteLine();

            Console.Write("array init time:");

 

            Console.Write(stopWatch.ElapsedMilliseconds.ToString());

            stopWatch.Reset();

            stopWatch.Start();

            Console.WriteLine();

           

            for (int i = 0; i < COUNT; i++)

            {

                list.Add(i) ;

            }

            int theListTotal = 0;

            foreach (int v in list)

            {

                //theListTotal += v;

            }

            stopWatch.Stop();

            Console.WriteLine("the value of Total for list:{0}", theListTotal);

            Console.Write("list init time:");

            Console.Write(stopWatch.ElapsedMilliseconds.ToString());

            stopWatch.Reset();

            Console.Read();

        }

       修改COUNT=1000,10000,100000,1000000依次输入为：

    

the count is:1000

the value of Total for array:0

array init time:0

the value of Total for list:0

list init time:0
 
the count is:10000

the value of Total for array:0

array init time:0

the value of Total for list:0

list init time:0
 
the count is:100000

the value of Total for array:0

array init time:0

the value of Total for list:0

list init time:1
 
the count is:1000000

the value of Total for array:0

array init time:7

the value of Total for list:0

list init time:17
 
the count is:10000000

the value of Total for array:0

array init time
4000
:77

the value of Total for list:0

list init time:218
（不同的硬件配置会有不同的结果）
从上面的结果来看array的效率要比List的要高一些，当数组长度不是很大时，两者没什么区别，建议用List<>，毕竟是可变长度，可以Add;特殊应用还是建议用array，
不提倡用ArrayList.

 
引用自cnblogs的文章。