VBA 中的哈希表/关联数组
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19-09-2019 - |
题
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。有可能吗?
您可以链接到一篇文章或者更好地发布代码吗?
解决方案
我认为您正在寻找 Microsoft Scripting Runtime 库中找到的 Dictionary 对象。(从 VBE 中的“工具...引用”菜单添加对项目的引用。)
它几乎适用于任何可以适应变体的简单值(键不能是数组,并且尝试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,您还可以使用 VBA Collection 对象。
我不知道是否真的对任何东西进行哈希处理,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 确实使用 哈希表 内部。)
其他提示
我用弗朗切斯科Balena的Hashtable类多次在过去,当集合或字典不是一个完美的结合,我只需要一个哈希表。
在这里,我们去...只是将代码复制到一个模块,它已经准备好使用
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VB使用(A)应用程序:
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
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