c# for foreach执行效率比较

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一直不了解for foreach执行效率特写了以下一段代码进行测试。

代码如下：

DateTime dt5 = DateTime.Now;            ArrayList a = new ArrayList();            Random r = new Random();            for (int i = 0; i < 10000000; i++)            {                a.Add("string" + r.Next().ToString());            }            DateTime dt6 = DateTime.Now;            TimeSpan ts3 = dt6 - dt5;            label9.Text = ts3.TotalMilliseconds.ToString();            int iCount = a.Count;            DateTime dt1 = DateTime.Now;            foreach (string s in a)            {            }            DateTime dt2 = DateTime.Now;            TimeSpan ts1 = dt2 - dt1;            label2.Text = ts1.TotalMilliseconds.ToString();            dt1 = DateTime.Now;            foreach (string s in a)            {            }            dt2 = DateTime.Now;            ts1 = dt2 - dt1;            label3.Text = ts1.TotalMilliseconds.ToString();            dt1 = DateTime.Now;            foreach (string s in a)            {            }            dt2 = DateTime.Now;            ts1 = dt2 - dt1;            label4.Text = ts1.TotalMilliseconds.ToString();                        StringBuilder sb2 = new StringBuilder();            DateTime dt3 = DateTime.Now;            for (int i = 0; i < iCount; i++)            {                string s = a[i] as string;            }            DateTime dt4 = DateTime.Now;            TimeSpan ts2 = dt4 - dt3;            label6.Text = ts2.TotalMilliseconds.ToString();            sb2 = new StringBuilder();            dt3 = DateTime.Now;            for (int i = 0; i < iCount; i++)            {                string s = a[i] as string;            }            dt4 = DateTime.Now;            ts2 = dt4 - dt3;            label7.Text = ts2.TotalMilliseconds.ToString();            sb2 = new StringBuilder();            dt3 = DateTime.Now;            for (int i = 0; i < iCount; i++)            {                string s = a[i] as string;            }            dt4 = DateTime.Now;            ts2 = dt4 - dt3;            label8.Text = ts2.TotalMilliseconds.ToString();

代码可以从下载地址http://download.csdn.net/detail/devgis/6987203

for foreach对同一arraylist对象进行1000万次操作进行比较结果如下

通过比较发现for循环的效率高如有异议欢迎讨论。

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