Question

在我的VBA程序中，我有一本词典

Dim dic As Variant
Set dic = CreateObject("Scripting.Dictionary")

我正在添加一堆字符串项（假设为100），其中一些具有值""

示例：

  Key    |   Value
-------------------
  "A"    |    1
  "B"    |    ""
  "C"    |    3
  "D"    |    4
  "E"    |    ""
 etc.

我知道有一种方法可以使用dic.Count("A")来计算密钥出现次数，但我想计算一下我的字典中有多少项具有值""（在我的示例中为2）而没有循环通过每个项目。

我尝试了以下但没有成功：

MsgBox "dic.item()count=" & dic.Item("").Count
MsgBox "dic.item()count=" & dic("").Count

如何实现这一目标？有没有类似dic.Value("").Count的方法？

Answer 1

~~这很难看，但它不是循环：~~

事实证明，即使是超大字典，这种方法也能很快地运行。

'Convert the Dictionary to an Array
MyArray = dic.Items
'Convert the Array to a String
MyString = Join(MyArray, ";")
'Blank Items in the Dictionary will result in ";;" appearing in the String
'Split the String on ;;
MyArray = Split(MyString, ";;", -1, vbTextCompare)
'A String with no ";;"'s will result in a 1 element array
'A String with 2 occurances of ;; will give a 3 element array
NumberOfBlankItems = UBound(MyArray)

进行了一些编辑来修复一些小的逻辑错误（Split是错误的参数数量，因为它是一个基于零的数组，所以不需要减去1）

另外，我使用20,000元素字典进行测试，并且在循环字典与此方法之间没有明显的速度差异。也许它不像我想象的那么难看......

我使用此代码再做了一次测试：

Sub DictionaryTest()
    Dim dic As New Dictionary 'Variant
    Dim r As Long
    Dim key As Variant
    Dim myArray As Variant
    Dim mystring As String
    Dim NumberOfBlankItems As Integer

    Set dic = CreateObject("Scripting.Dictionary")
    For r = 1 To 500000
        dic.Add "Key " & r, CInt(Int((600 * Rnd()) + 1))
    Next

    r = 0

    Debug.Print "Starting count by looping: " & Now()

    For Each key In dic
        If dic.item(key) = 300 Then r = r + 1
    Next

    Debug.Print "Count by looping: " & r

    Debug.Print "Starting count by splitting: " & Now()

    myArray = dic.Items
    mystring = Join(myArray, ";")
    myArray = Split(mystring, "300;", -1, vbTextCompare)
    NumberOfBlankItems = UBound(myArray)
    Debug.Print "Count by splitting: " & NumberOfBlankItems

    Debug.Print "Finish time: " & Now()
End Sub

立即窗口：

Starting count by looping: 6/15/2016 3:02:47 PM
Count by looping: 818
Starting count by splitting: 6/15/2016 3:03:16 PM
Count by splitting: 818
Finish time: 6/15/2016 3:03:16 PM

正如你所看到的，即使字典中有500,000个条目，分割字符串所花费的时间（一个字符串几乎不超过20亿个字符！）仍然只有大约1秒！

计算值出现而不循环字典

1 个答案: