VBA written in Excel for Windows not working on Mac - macos

Question

I have a set of macros to hide and unhide columns based on the contents of a specific row. They were all written in Excel 2013 for Windows (running in parallels on my MBA, if that's relevant) and work fine there. But when I open the worksheet in Excel 2011 for Mac, the macros give odd results. The "unhide all columns" macro works fine; the other functions get as far as hiding all columns but not as far as unhiding the ones I want to see.
I can only assume Excel for Mac is having a problem with what's in the FOR EACH loop, but I can't figure out what! I'd appreciate any guidance: I need to get this system working on both Windows and Mac.
Code below.
This function works:
Sub GANTT_Filter_Show_All()
Dim rngDates As Range
Set rngDates = Range("GANTT_Dates")
rngDates.EntireColumn.Hidden = False
End Sub
But this one only hides all the columns:
Sub GANTT_Filter_This_Quarter()
Dim intCurrentMonth As Integer, intCurrentYear As Integer, rngDates As Range, cell As Range
Dim intCurrentQuarterMonths(3) As Integer
Set rngDates = Range("GANTT_Dates")
intCurrentMonth = DatePart("m", Date)
intCurrentYear = DatePart("yyyy", Date)
'loading months of current quarter into an array intCurrentMonth
Select Case intCurrentMonth
Case 1 To 3
intCurrentQuarterMonths(0) = 1
intCurrentQuarterMonths(1) = 2
intCurrentQuarterMonths(2) = 3
Case 4 To 6
intCurrentQuarterMonths(0) = 4
intCurrentQuarterMonths(1) = 5
intCurrentQuarterMonths(2) = 6
Case 7 To 9
intCurrentQuarterMonths(0) = 7
intCurrentQuarterMonths(1) = 8
intCurrentQuarterMonths(2) = 9
Case 10 To 12
intCurrentQuarterMonths(0) = 10
intCurrentQuarterMonths(1) = 11
intCurrentQuarterMonths(2) = 12
End Select
'hiding all columns
rngDates.EntireColumn.Hidden = True
'comparing each column to array of months in current quarter and hiding if false
For Each cell In rngDates
For Each v In intCurrentQuarterMonths
If v = DatePart("m", cell.Value) And DatePart("yyyy", cell.Value) = intCurrentYear Then cell.EntireColumn.Hidden = False
Next v
Next cell
Application.Goto Reference:=Range("a1"), Scroll:=True
End Sub

Answer 1

I'm with #Steven on this one, nothing obviously wrong with the code. I'm not a Mac user, but it's entirely possible that there's some weirdness around the date functions, particularly those that require formatting to resolve.
I would try replacing the calls to DatePart() with calls to Month() and Year() in situations like this - even for non-Mac users. It doesn't rely on parsing the strings for formatting, so it's much more efficient (and easy to read):
Sub Benchmarks()
Dim starting As Double, test As Date, i As Long
test = Now
starting = Timer
For i = 1 To 1000000
Year test
Next i
Debug.Print "Elapsed: " & (Timer - starting)
starting = Timer
For i = 1 To 1000000
DatePart "yyyy", test
Next i
Debug.Print "Elapsed: " & (Timer - starting)
End Sub
Since you likely can't run the benchmark...
Elapsed for Year(): 0.109375
Elapsed for DatePart(): 0.515625
Also note that in addition to this, the dates in the column you're searching are coming through as Variants, it may help to explicitly cast them to dates:
If v = Month(CDate(cell.Value)) And intCurrentYear = Year(CDate(cell.Value)) Then
cell.EntireColumn.Hidden = False
End If