你调用的对象是空的？网络
我这里有这样的代码：
Dim MasterIndex As String()()
Private Function Lookup(ByVal Search_path As String) As Integer
Dim i As Integer = 0
Do Until MasterIndex(i)(0) Is Nothing
If Search_path = MasterIndex(i)(0) Then
Return MasterIndex(i)(1)
End If
Loop
Return -1
End Function
这给了我在 Do Until 行上发生的错误 对象引用未设置到对象的实例。这是为什么呢？我该如何解决这个问题？
I have this code here:
Dim MasterIndex As String()()
Private Function Lookup(ByVal Search_path As String) As Integer
Dim i As Integer = 0
Do Until MasterIndex(i)(0) Is Nothing
If Search_path = MasterIndex(i)(0) Then
Return MasterIndex(i)(1)
End If
Loop
Return -1
End Function
Which gives me the error Object reference not set to an instance of an object occuring on the Do Until line. Why is this? How can I fix this?
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MasterIndex 变量从未被分配，这就是为什么出现异常的原因。
您应该首先通过调用 New() 构造函数来实例化 MasterIndex：
并在调用 Lookup 函数之前用数据填充它。
像这样的东西：
The MasterIndex variable is never assigned that is why you have the exception
You should instantiate MasterIndex first by calling the New() constructor:
and fill it with data before calling the Lookup function.
Something like:
MasterIndex 未初始化或 MasterIndex(0) 未初始化。
假设您在程序的其他地方执行此操作，您能否显示初始化该变量的代码？
如果您在该行上放置一个断点并检查 MasterIndex 会发生什么？
Either MasterIndex is not initialized or MasterIndex(0) is not initialized.
Can you show the code that initializes that variable, assuming you do that somewhere else in the program?
What happens if you put a breakpoint on that line and examine MasterIndex?