private void button1_Click(object sender, EventArgs e)
        {
            string[] xxy = { "txtsjdbdh", "txtxmjldh" }; 
            foreach (string i in xxy) 
            {
                Control[] cs = this.Controls.Find(i, true);
                if (cs != null && cs.Length > 0)
                {
                    TextBox tb = cs[0] as TextBox;
                    if (tb != null)
                    {
                        tb.Text = i;
                    }
                }
            } 
        }

------解决方案--------------------
字符串有text属性呢？

string[] xxy = { "txtsjdbdh", "txtxmjldh" };///这是textbox的name集合？

假如是的话
foreach (string i in xxy) 
{

////这里面你应该通过i 去找你页面中的textbox 找到后在 转换为textbox   然后在给属性赋值.
而不是想你这样
  i.text = "sfds";
}


还有你都知道TextBox的name了 干嘛不直接txtsjdbdh.text="00000000";呢

或者

list<objct> textobj=new list<objct>()

textobj.add(txtsjdbdh)
textobj.add(txtxmjldh)

foreach (objct text in textobj) 
{
textbox test=text as textbox;
if(test is textbox)
{
  test.text = "sfds";
}

}






------解决方案--------------------
数组里面存放两个textbox控件名称

string[] xxy = { "txtsjdbdh", "txtxmjldh" };
foreach (textbox i in xxy) 
{
 i.text = "sfds";
}


------解决方案--------------------
另外textbox命名规则最好写成   txt_sjdbdh,txt_xmjldh
这样比较美观，也比较看懂

------解决方案--------------------
C# code


 foreach (Control c in this.Controls)
            {
                if (c.GetType() == typeof(TextBox))
                {
                    TextBox t = c as TextBox;
                    t.Text = "fdsaf";
                }

------解决方案--------------------
        List<TextBox> txtList = new List<TextBox>();
       public Form25()
       {
           InitializeComponent();

           txtList.Add(textBox1);
           txtList.Add(textBox2);

           foreach (TextBox tb in txtList)
           {
               tb.Text = "fdsaf";
           }
       }