貞愛講

private void TextBox1_Validating(object sender, System.ComponentModel.CancelEventArgs e)
        {
            if (TextBox1.Text==string.Empty)
                errorProvider1.SetError(TextBox1, "");
            else
                if (!(Regex.IsMatch(TextBox1.Text,
                              @"^([a-zA-Z0-9_\-])([a-zA-Z0-9_\-\.]*)@(\[((25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9][0-9]|[0-9])\.){3}|((([a-zA-Z0-9\-]+)\.)+))([a-zA-Z]{2,}|(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9][0-9]|[0-9])\])$")))
                {
                    errorProvider1.SetError(TextBox1, "電子郵件地址務必採用 abc@cccc.ccc.cc 的格式。");
                    e.Cancel = true;
                }
                else
                {
                    errorProvider1.SetError(TextBox1, "");
                    e.Cancel = false;
                }
        }