string与stringBuilder的性能区别(转)

自己动手测试了，性能差距还比较大：

Console.WriteLine("Class String:");
string strClass = string.Empty;
DateTime BeginTime = System.DateTime.Now;
Console.WriteLine(BeginTime.ToString());
for (int i = 0; i <= 99999; i++)
{
    strClass += i.ToString();
}
DateTime EndTime = System.DateTime.Now;
Console.WriteLine(EndTime.ToString());
TimeSpan ts = EndTime.Subtract(BeginTime);
Console.WriteLine("class string cost time is:" + ts.TotalMilliseconds.ToString() + "ms");
Console.WriteLine(); Console.WriteLine("Class StringBulid:");
StringBuilder sb = new StringBuilder();
Console.WriteLine(System.DateTime.Now.ToString());
BeginTime = System.DateTime.Now;
for (int i = 0; i <= 99999; i++)
{
    sb.Append(i.ToString());
}
Console.WriteLine(System.DateTime.Now.ToString());
EndTime = System.DateTime.Now;
ts = EndTime.Subtract(BeginTime);
Console.WriteLine("class stringbuild cost time is:" + ts.TotalMilliseconds.ToString() + "ms");

结果：
Class String:
2008-12-24 13:33:29
2008-12-24 13:34:29
class string cost time is:60453.125ms
Class StringBulid:
2008-12-24 13:34:29
2008-12-24 13:34:29
class stringbuild cost time is:31.25ms
请按任意键继续. . .