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: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.