天天向上

   1: private void button1_Click(object sender, EventArgs e)

   2:         {

   3:             using (FileStream fs = new FileStream(@"c:\log.txt",System.IO.FileMode.Create))

   4:             {

   5:                 object obj = fs as object;

   6:                 if (obj != null)

   7:                 {

   8:                     MessageBox.Show("轉換為Object成功！", "提示！");

   9:                 }

  10:                 else

  11:                 {

  12:                     MessageBox.Show("轉換為Object不成功！", "提示！");

  13:                 }

  14:                 Stream strm = obj as Stream;

  15:                 if (strm != null)

  16:                 {

  17:                     MessageBox.Show("轉換為Stream成功！", "提示！");

  18:                 }

  19:                 else

  20:                 {

  21:                     MessageBox.Show("轉換為Stream不成功！", "提示！");

  22:                 }

  23:                 string str = obj as string;

  24:                 if (str != null)

  25:                 {

  26:                     MessageBox.Show("轉換為string成功！", "提示！");

  27:                 }

  28:                 else

  29:                 {

  30:                     MessageBox.Show("轉換為string不成功！", "提示！");

  31:                 }

  32:  

  33:                 StreamReader f = obj as StreamReader;

  34:                 if (str != null)

  35:                 {

  36:                     MessageBox.Show("轉換為StreamReader成功！", "提示！");

  37:                 }

  38:                 else

  39:                 {

  40:                     MessageBox.Show("轉換為StreamReader不成功！", "提示！");

  41:                 }

  42:  

  43:             }

  44:         }