XML閱讀子不工作

Question

我正在寫一個從給定路徑讀取XML文件，然後將其加載到對象數組中的子。出於某種原因，該算法對名稱工作正常，但拒絕使用成本和類型標籤。到底是怎麼回事？

（UPDATE：拒絕工作意味着它返回一個空字符串，或在成本的情況下：0）

這裏是我的代碼：

Public Sub New(ByVal Path As String) 
    Try 
     Dim XML As New XmlTextReader(Path) 
     Try 
      Dim Bool As Boolean = False 
      Dim Name As String = "" 
      Dim Cost As Double = 0 
      Dim Type As String = "" 
      While True 
       XML.Read() 
       If Bool Then 
        Select Case XML.Name 
         Case Is = "name" 
          XML.Read() 
          Name = XML.Value 
         Case Is = "cost" 
          XML.Read() 
          Double.TryParse(XML.Value, Cost) 
         Case Is = "type" 
          XML.Read() 
          Type = XML.Value 
        End Select 
       End If 
       If XML.Name = "card" Then 
        Bool = True 
       End If 
       If Not CheckNulls(Name, Cost, Type) Then //CheckNulls returns true if all arguments passed to it are either empty strings, or 0 
        Dim Card As New Card(Name, Cost, Type) 
        Deck.Add(Card) 
        Cost = 0 
        Name = "" 
        Type = "" 
        Bool = False 
       End If 
      End While 
     Catch Ex As Exception 
      Exit Sub 
     End Try 
    Catch Ex As Exception 
     MsgBox("The System has encountered an error. Running the software anymore could cause a serious malfunction. Please exit now", MsgBoxStyle.OkOnly, "Error Message") 
    End Try 
End Sub 

這裏是XML文件： 蒙娜麗莎藝術 個圓點 35.85 藝術

Answer 1

讀取XML數據，你正在做的方式是既笨拙以及容易出錯。使用XPath Expressions從XML文件中提取感興趣的數據要好得多，它只需一行代碼即可獲取數據。

您可以瞭解更多關於XPath Expressions語法這裏，以讓自己開始：

http://www.w3schools.com/xsl/xpath_syntax.asp

要學習如何在VB.NET代碼使用XPath表達式，你會發現有很多的有趣的文章互聯網。其中之一，說明它在一個易於理解的語言是在這裏：

http://www.aspsnippets.com/Articles/XmlDocument-XPath-Example-Select-XML-nodes-by-Name-and-Attribute-values-in-C-and-VBNet.aspx