VBA Excel - Passing Array is not updating the reference - arrays

Question

I am working in a function that will read a range of cells in one spreadsheet and write it on another spreadsheet.
To do that, I'm reading all of the cells from a source and target spreadsheet and then writing to an array to compare if there is already the value on the target spreadsheet
The point here, is that I can save the the values inside of the Array, but my functions are returning an empty array. Following are my code snippet.
Private Sub UpdateBacklog_Click()
Dim ArrSource() As String
Dim ArrTarget() As String
sourceRead Wks, ArrSource
targetRead Cwks, ArrTarget
End Sub
Function targetRead(targetWks, arrayT() As String)
.
.
rowCount = targetWks.Cells(Rows.Count, C_TRG_ID_COL).End(xlUp).Row
currentRow = C_TRG_ROW
id = 1
ReDim arrayT(1, 1)
If currentRow <= rowCount Then
For currentRow = currentRow To rowCount
ReDim arrayT(id, 1)
arrayT(id, 1) = targetWks.Cells(currentRow, C_TRG_ID_COL).Value
id = id + 1
DoEvents
Next
End If
End Function
Function sourceRead(sourceWks, arrayS() As String)
.
.
rowCount = sourceWks.Cells(Rows.Count, C_SRC_ID_COL).End(xlUp).Row
currentRow = C_SRC_ROW
id = 1
If currentRow <= rowCount Then
For currentRow = currentRow To rowCount
sourceStatus = sourceWks.Cells(currentRow, C_SRC_STS_COL).Value
ReDim arrayS(id, 1 To 4)
arrayS(id, 1) = sourceWks.Cells(currentRow, C_SRC_ID_COL).Value
arrayS(id, 2) = sourceWks.Cells(currentRow, C_SRC_DSC_COL).Value
arrayS(id, 3) = sourceWks.Cells(currentRow, C_SRC_PRC_COL).Value
arrayS(id, 4) = sourceStatus
id = id + 1
DoEvents
Next
End If
End Function

Answer 1

Try returning the arrays from the functions.
Private Sub UpdateBacklog_Click()
Dim ArrSource() As String
Dim ArrTarget() As String
ArrSource = sourceRead(Wks, ArrSource)
ArrTarget = targetRead(Cwks, ArrTarget)
End Sub
Function targetRead(targetWks, arrayT() As String)
' lots of stuff here
targetRead = arrayT
End Function
Function sourceRead(sourceWks, arrayS() As String)
' lots of stuff here
sourceRead = arrayS
End Function
You were treating the functions like subs that would change the byRef parameter that was being passed into them. A function is meant to return a value so assign the altered array(s) back into themselves. For all intents and purposes, this is no different than replacing the periods in a string with commas in something like,
tmp = replace(tmp, chr(46), chr(44))