Dictionary with array as the value

[Shamusvw]

Hi, I have been battling to understand why an array is not being updated where the array is in place of a key/value pair.
I have the following in VBA:

Dim testDict As Object
Dim testKey As String
Dim arr(1) As Double
Set testDict = CreateObject("Scripting.Dictionary")
testKey = "TestKey"
arr(0) = 64
arr(1) = 0
testDict.Add testKey, arr
Debug.Print "Before: "; testDict(testKey)(0)
testDict(testKey)(0) = testDict(testKey)(0) + 126.5
Debug.Print "After: "; testDict(testKey)(0)

And in my Immediate Window I get the following:
Before: 64
After: 64

However, my expectation is that I would get:
Before: 64
After: 190.5

 

[Fluff]

You cannot change the value in the array directly like that, try it like

   Dim testDict As Object
   Dim testKey As String
   Dim arr(1) As Double
   Dim Tmp As Variant
   
   Set testDict = CreateObject("Scripting.Dictionary")
   testKey = "TestKey"
   arr(0) = 64
   arr(1) = 0
   testDict.Add testKey, arr
   Debug.Print "Before: "; testDict(testKey)(0)
   Tmp = testDict(testKey)
   Tmp(0) = Tmp(0) + 126.5
   
   testDict(testKey) = Tmp
   Debug.Print "After: "; testDict(testKey)(0)

 

[JB2020]

Can't tell you exactly why it doesn't work, but you could workaround it like this:

Editing the original array:

    Dim testDict As Object
    Dim testKey As String
    Dim arr(1) As Double
    
    Set testDict = CreateObject("Scripting.Dictionary")
    testKey = "TestKey"
    arr(0) = 64
    arr(1) = 0
    testDict.Add testKey, arr
    
    Debug.Print "Before: "; testDict(testKey)(0)
    arr(0) = testDict(testKey)(0) + 126.5
    testDict(testKey) = arr
    Debug.Print "After: "; testDict(testKey)(0)

Storing the array in a variable:

    Dim testDict As Object
    Dim testKey As String
    Dim arr(1) As Double
    Dim tempArr As Variant
    
    Set testDict = CreateObject("Scripting.Dictionary")
    testKey = "TestKey"
    arr(0) = 64
    arr(1) = 0
    testDict.Add testKey, arr
    
    Debug.Print "Before: "; testDict(testKey)(0)
    tempArr = testDict(testKey)
    tempArr(0) = tempArr(0) + 126.5
    testDict(testKey) = tempArr
    Debug.Print "After: "; testDict(testKey)(0)

 

[JB2020]

You cannot change the value in the array directly like that, try it like

   Dim testDict As Object
   Dim testKey As String
   Dim arr(1) As Double
   Dim Tmp As Variant
  
   Set testDict = CreateObject("Scripting.Dictionary")
   testKey = "TestKey"
   arr(0) = 64
   arr(1) = 0
   testDict.Add testKey, arr
   Debug.Print "Before: "; testDict(testKey)(0)
   Tmp = testDict(testKey)
   Tmp(0) = Tmp(0) + 126.5
  
   testDict(testKey) = Tmp
   Debug.Print "After: "; testDict(testKey)(0)

Apologies, Fluff. Hadn't seen you had already responded to this when I posted.

 

[Shamusvw]

Thank you, I appreciate the feedback. I've implemented the solution by Fluff

 

[Fluff]

Glad we could help & thanks for the feedback.