主题：如何根据表的某列生成目录树的问题

Dim cd As New List(Of Integer)       ''科目代码长度
For Each dr As DataRow In dt.DataRows
    If cd.Contains(dr("科目代码").Length)=False And dr.IsNull("科目代码")=False Then
        cd.Add(dr("科目代码").Length)
    End If
Next

Dim gz() As Integer
gz=cd.ToArray    ''科目长度转换为数组
Array.Sort(gz)   ''科目长度排序

Dim i As Integer
If gz.Length>0 Then
    For i=gz.Length-1 To 0 Step -1 ''
        If i>0  Then
            gz(i)=gz(i)-gz(i-1)
        End If
    Next
End If

For Each dr As DataRow In dt.Select("","科目代码")
    If dr.IsNull("科目代码") = False AndAlso dr("科目代码").Length = gz(0) Then
        nd = tr.Nodes.Add(dr("科目代码"),dr("科目代码") & " " & dr("科目名称"))
        Functions.Execute("科目树递归函数",nd,dt,gz,1)
    End If
Next
tr.ResumeRedraw()

科目树递归函数：

Dim nd As WinForm.TreeNode = args(0)
Dim dt As DataTable = args(1)
Dim gz() As Integer = args(2)
Dim idx As Integer = args(3)
If idx < gz.Length Then
    For Each dr As DataRow In dt.Select("","科目代码") '按代码顺序添加
        Dim km As String = dr("科目代码")
       
        If km.StartsWith(nd.name) AndAlso km.Length = nd.Name.Length + gz(idx) Then
            Dim sum As Integer = 0
            For i As Integer = 0 To gz.Length - 1
                sum += gz(i)
                If km.Length = sum  Then
                    Dim cd As Winform.TreeNode = nd.Nodes.Add(km,km & " " & dr("科目名称"))
                    Functions.Execute("科目树递归函数",cd,dt,gz,idx+1)
                    Exit For
                End If
            Next
        End If
    Next
End If