代碼,我只是新的aspx.net呼叫數組變量從後面
我嘗試從aspx.vb但問題調用數組變量發生
對象引用不設置到對象的實例。
這裏的代碼aspx.vb:
Imports System.Data.OleDb
Partial Class MasterPage Inherits System.Web.UI.MasterPage
Public count() As String
Public Location() As String
Public m As Integer = 1
Public i As Integer = 1
Public Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim connectString As String = "Provider=Microsoft.Jet.OLEDB.4.0;" & _
"Data Source=" & Server.MapPath("db1.mdb")
Dim cn As OleDbConnection = New OleDbConnection(connectString)
cn.Open()
Dim selectString As String = "SELECT * FROM Landslides"
Dim cmd As OleDbCommand = New OleDbCommand(selectString, cn)
Dim reader As OleDbDataReader = cmd.ExecuteReader()
While (reader.Read())
count(m) = reader("Bil").ToString
Location(m) = reader("Location").ToString
m += 1
End While
End Sub
代碼在ASPX:
<% For i = 1 To m Step 1 %>
<li><br /><a href='Second.aspx?id='> <%Response.Write(Location(m))%> </a></li>
<%Next%>
當我嘗試編譯的結果是好的。但是當我嘗試加載網站時會出現錯誤。我正在使用visual studio 2005
檢查循環,如果'讀者( 「膽紅素」)''是null'。如果'reader(「Bill」)'爲空,則直接調用'ToString()'方法,該方法將拋出一個空引用異常。 –
是啊已經檢查它。它不是空的。但我嘗試更改這樣的錯誤行 count(0)=「你好」 錯誤仍然存在 – ZackRich
重複的[什麼是NullReferenceException,我該如何解決它?](http://stackoverflow.com/問題/ 4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) –