vba - VBA中的哈希表/关联数组

Question

我似乎找不到解释如何在 VBA 中创建哈希表或关联数组的文档。甚至可能吗？

您可以链接到文章或更好地发布代码吗？

Answer 1

我认为您正在寻找 Microsoft 脚本运行时库中的 Dictionary 对象。（从 VBE 的 Tools...References 菜单中添加对项目的引用。）

它几乎适用于任何可以适合变体的简单值（键不能是数组，并且试图使它们成为对象没有多大意义。请参阅下面@Nile 的评论。）：

Dim d As dictionary
Set d = New dictionary

d("x") = 42
d(42) = "forty-two"
d(CVErr(xlErrValue)) = "Excel #VALUE!"
Set d(101) = New Collection

如果您的需求更简单并且只需要字符串键，您也可以使用 VBA 集合对象。

我不知道两者是否真的对任何东西都进行了哈希处理，因此如果您需要类似哈希表的性能，您可能需要进一步挖掘。（编辑：Scripting.Dictionary 确实在内部使用了哈希表。）

Answer 2

过去我曾多次使用Francesco Balena 的 HashTable 类，当时集合或字典并不完美，我只需要一个 HashTable。

Answer 3

尝试使用 Dictionary 对象或 Collection 对象。

http://visualbasic.ittoolbox.com/documents/dictionary-object-vs-collection-object-12196

Answer 4

开始吧...只需将代码复制到一个模块中，即可使用

Private Type hashtable
    key As Variant
    value As Variant
End Type

Private GetErrMsg As String

Private Function CreateHashTable(htable() As hashtable) As Boolean
    GetErrMsg = ""
    On Error GoTo CreateErr
        ReDim htable(0)
        CreateHashTable = True
    Exit Function

CreateErr:
    CreateHashTable = False
    GetErrMsg = Err.Description
End Function

Private Function AddValue(htable() As hashtable, key As Variant, value As Variant) As Long
    GetErrMsg = ""
    On Error GoTo AddErr
        Dim idx As Long
        idx = UBound(htable) + 1

        Dim htVal As hashtable
        htVal.key = key
        htVal.value = value

        Dim i As Long
        For i = 1 To UBound(htable)
            If htable(i).key = key Then Err.Raise 9999, , "Key [" & CStr(key) & "] is not unique"
        Next i

        ReDim Preserve htable(idx)

        htable(idx) = htVal
        AddValue = idx
    Exit Function

AddErr:
    AddValue = 0
    GetErrMsg = Err.Description
End Function

Private Function RemoveValue(htable() As hashtable, key As Variant) As Boolean
    GetErrMsg = ""
    On Error GoTo RemoveErr

        Dim i As Long, idx As Long
        Dim htTemp() As hashtable
        idx = 0

        For i = 1 To UBound(htable)
            If htable(i).key <> key And IsEmpty(htable(i).key) = False Then
                ReDim Preserve htTemp(idx)
                AddValue htTemp, htable(i).key, htable(i).value
                idx = idx + 1
            End If
        Next i

        If UBound(htable) = UBound(htTemp) Then Err.Raise 9998, , "Key [" & CStr(key) & "] not found"

        htable = htTemp
        RemoveValue = True
    Exit Function

RemoveErr:
    RemoveValue = False
    GetErrMsg = Err.Description
End Function

Private Function GetValue(htable() As hashtable, key As Variant) As Variant
    GetErrMsg = ""
    On Error GoTo GetValueErr
        Dim found As Boolean
        found = False

        For i = 1 To UBound(htable)
            If htable(i).key = key And IsEmpty(htable(i).key) = False Then
                GetValue = htable(i).value
                Exit Function
            End If
        Next i
        Err.Raise 9997, , "Key [" & CStr(key) & "] not found"

    Exit Function

GetValueErr:
    GetValue = ""
    GetErrMsg = Err.Description
End Function

Private Function GetValueCount(htable() As hashtable) As Long
    GetErrMsg = ""
    On Error GoTo GetValueCountErr
        GetValueCount = UBound(htable)
    Exit Function

GetValueCountErr:
    GetValueCount = 0
    GetErrMsg = Err.Description
End Function

要在您的 VB(A) 应用程序中使用：

Public Sub Test()
    Dim hashtbl() As hashtable
    Debug.Print "Create Hashtable: " & CreateHashTable(hashtbl)
    Debug.Print ""
    Debug.Print "ID Test   Add V1: " & AddValue(hashtbl, "Hallo_0", "Testwert 0")
    Debug.Print "ID Test   Add V2: " & AddValue(hashtbl, "Hallo_0", "Testwert 0")
    Debug.Print "ID Test 1 Add V1: " & AddValue(hashtbl, "Hallo.1", "Testwert 1")
    Debug.Print "ID Test 2 Add V1: " & AddValue(hashtbl, "Hallo-2", "Testwert 2")
    Debug.Print "ID Test 3 Add V1: " & AddValue(hashtbl, "Hallo 3", "Testwert 3")
    Debug.Print ""
    Debug.Print "Test 1 Removed V1: " & RemoveValue(hashtbl, "Hallo_1")
    Debug.Print "Test 1 Removed V2: " & RemoveValue(hashtbl, "Hallo_1")
    Debug.Print "Test 2 Removed V1: " & RemoveValue(hashtbl, "Hallo-2")
    Debug.Print ""
    Debug.Print "Value Test 3: " & CStr(GetValue(hashtbl, "Hallo 3"))
    Debug.Print "Value Test 1: " & CStr(GetValue(hashtbl, "Hallo_1"))
    Debug.Print ""
    Debug.Print "Hashtable Content:"

    For i = 1 To UBound(hashtbl)
        Debug.Print CStr(i) & ": " & CStr(hashtbl(i).key) & " - " & CStr(hashtbl(i).value)
    Next i

    Debug.Print ""
    Debug.Print "Count: " & CStr(GetValueCount(hashtbl))
End Sub