比较C#中几种常见的复制字节数组方法的效率[转]

[原文链接]

在日常编程过程中，我们可能经常需要Copy各种数组，一般来说有以下几种常见的方法：Array.Copy，IList<T>.Copy，BinaryReader.ReadBytes，Buffer.BlockCopy,以及System.Buffer.memcpyimpl，由于最后一种需要使用指针，所以本文不引入该方法。

本次测试，使用以上前4种方法，各运行1000万次，观察结果。

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;

namespace BenchmarkCopyArray
{
class Program
{
private const int TestTimes = 10000000;
static void Main()
{
var testArrayCopy = new TestArrayCopy();
TestCopy(testArrayCopy.TestBinaryReader, "Binary.ReadBytes");
TestCopy(testArrayCopy.TestConvertToList, "ConvertToList");
TestCopy(testArrayCopy.TestArrayDotCopy, "Array.Copy");
TestCopy(testArrayCopy.TestBlockCopy, "Buffer.BlockCopy");
Console.Read();
}

private static void TestCopy(Action testMethod, string methodName)
{
var stopWatch = new Stopwatch();
stopWatch.Start();
for (int i = 0; i < TestTimes; i++)
{
testMethod();
}
testMethod();
stopWatch.Stop();
Console.WriteLine("{0}: {1} seconds, {2}.", methodName, stopWatch.Elapsed.Seconds, stopWatch.Elapsed.Milliseconds);
}
}

class TestArrayCopy
{
private readonly byte[] _sourceBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

public void TestBinaryReader()
{
var binaryReader = new BinaryReader(new MemoryStream(_sourceBytes));
binaryReader.ReadBytes(_sourceBytes.Length);
}

public void TestConvertToList()
{
IList<byte> bytesSourceList = new List<byte>(_sourceBytes);
var bytesNew = new byte[_sourceBytes.Length];
bytesSourceList.CopyTo(bytesNew, 0);
}

public void TestArrayDotCopy()
{
var bytesNew = new byte[_sourceBytes.Length];
Array.Copy(_sourceBytes, 0, bytesNew, 0, _sourceBytes.Length);
}

public void TestBlockCopy()
{
var bytesNew = new byte[_sourceBytes.Length];
Buffer.BlockCopy(_sourceBytes, 0, bytesNew, 0, _sourceBytes.Length);
}
}
}

运行结果如下：