有條件的寫作HTML

Question

我目前正在嘗試創建一個語句，如果它返回false，那麼標籤將在頁面上顯示一條錯誤消息。我試過用Response.Write沒有結果。

if (bannedDomainText.Text.Contains(".")) 
    File.AppendAllText(MapPath(FILE_PATH), "\r\n" + bannedDomainText.Text); 
else 
    Response.Write("<label>This isn't working!</label>"); 

Answer 1

的Html

<asp:Label ID="ErrorMessage" Visible="false"></asp:Label> 

代碼

if (bannedDomainText.Text.Contains(".")) 
    File.AppendAllText(MapPath(FILE_PATH), "\r\n" + bannedDomainText.Text); 
else 
{ 
    Message.Text = "This is working"; 
    Message.Visible = true; 
} 

Answer 2

定義服務器端label並將消息分配給其文本屬性。 You can hide this label or set its text to empty string when you do not want to show the message。

以HTML

<asp:Label id="lblMessage" runat="server" /> 

在代碼背後

if (bannedDomainText.Text.Contains(".")) 
    File.AppendAllText(MapPath(FILE_PATH), "\r\n" + bannedDomainText.Text); 
else 
    lblMessage.Text = "This is working";