vb.net 数据表到数组列表
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DataTable to ArrayList
提问by Flashidkz
I want to get value from datatable and then store it to the string() arraylist. datatable contain 3 column (columnA | columnB | columnC). I want to get all value from columnB and store it to arraylist.
我想从数据表中获取值，然后将其存储到 string() 数组列表中。数据表包含 3 列（columnA | columnB | columnC）。我想从 columnB 获取所有值并将其存储到 arraylist。
I have try something like this
我尝试过这样的事情
If myTableData.Rows.Count > 0 Then
For i As Integer = 0 To myTableData.Rows.Count - 1
Dim value() As String = myTableData.Rows(i)(1)
Next
End If
but when I compile that code, I got error message like this :
但是当我编译该代码时，我收到如下错误消息：
Unable to cast object of type 'System.String' to type 'System.String[]'
无法将“System.String”类型的对象转换为“System.String[]”类型
please help me.....
请帮我.....
回答by Tim Schmelter
You could do that with LINQ:
你可以用 LINQ 做到这一点：
Dim colBValues = (From row In myTableData Select colB = row(1).ToString).ToList
Or if you prefer the "old-school" way:
或者，如果您更喜欢“老派”方式：
Dim colBValues = New List(Of String)
For Each row As DataRow In myTableData.Rows
colBValues.Add(row(1).ToString)
Next
I've used a List(Of String)because it's type-safe, therefore you don't need to cast the values everytime. That makes code more readable, more failsafe and faster.
我使用了 aList(Of String)因为它是类型安全的，因此您不需要每次都转换值。这使得代码更具可读性、更安全和更快。
If you need it as String-Array, you could simply use ToArray:
如果你需要它作为字符串数组，你可以简单地使用ToArray：
Dim colBValues = (From row In myTableData Select colB = row(1).ToString).ToArray
回答by reshma k
Dim a() As String
Dim total As Integer
'Count the number of rows
total = myTableData.Rows.Count - 1
ReDim a(0 To total)
For i = 0 To total
a(i) = myTableData.Rows(i)(1)
Next
回答by nelek
This is really old question, but I'll provide one more variant of answer :
这确实是个老问题，但我将提供另一种答案：
Dim value = myTableData.Rows.OfType(Of DataRow).Select(Function(x) x(1).ToString()).ToArray
So, if You have more than one columnin Your DataTableYou can use x(columnIndex)instead 1.
因此，如果您column在 Your You 中有多个，则DataTable可以使用x(columnIndex)1。
