定义数组方法一：string[] myarray = new string[5];
           myarray[0] = "aaa";
           myarray[1] = "sss";
           myarray[2] = "ddd";
           myarray[3] = "fff";
           myarray[4] = "qqq";

定义数组方法二：Array myarr = Array.CreateInstance(GetType(string),5);
         myarr.SetValue("aaa", 0);
         myarr.SetValue("sss", 1);
         myarr.SetValue("ddd", 2);
         myarr.SetValue("eee", 3);
         myarr.SetValue("rrr", 4);

定义数组方法三：string[] str = new string[6];
             { "aaa","sss","ddd","fff","sss" ,"fff"};

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show.Text = str.GetValue(4).ToString()     //   得到数组中某个值

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找数组中某个值第一次出现的的位置： int i=Array.IndexOf(str,"ddd");

找数组中某个值最后一次出现的的位置： int i=Array.LastIndexOf(str, "ddd");

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Array.Reverse(str); //将数组翻转
Array.Sort(str); //将数组排序 按字母顺序                                      str都为数组名字

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foreach (string strings in str)        用foreach
        {
            mydropdownlist.Items.Add(strings);      //把数组的每个值付给空间dropdownlist
        }
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mydropdownlist.DataSource = str ;

mydropdownlist.DataBind();              //数据绑定