请编程遍历页面上所有TextBox控件并给它赋值为string.Empty？

答：
      foreach (System.Windows.Forms.Control control in this.Controls)
      {
      if (control is System.Windows.Forms.TextBox)
      {
        System.Windows.Forms.TextBox tb = (System.Windows.Forms.TextBox)control ;
        tb.Text = String.Empty ;
      }
      }