VBA Excel: comparison of dates under different locale settings - excel

Question

I have a column in "dd-mm-yy hh:mm" format that formed as a result of some action on UserForm:
Dim ws as Worksheet
Set ws = Worksheets("Logs")
With ws
For i = 1 to Me.ListBox1.ListCount - 1
.Cells(lRow + 1 + i, 10).Value = CDate(VBA.Format(Me.ListBox1.List(i), "dd-mm-yy hh:mm"))
Next i
End With
I save the column to Variant variable to use later (to be used multiple times):
Dim arrTimeD As Variant
arrTimeD = Application.Transpose(.Range(TCL & "2:" & TCL & lRow).Value)
The locale date settings are European: "dd-mmm-yyyy"
The spreadsheet are used by different users, some have "dd-mmm" setting, others "mm-dd" etc.
I need to compare the dates in several uses. For, e.g.
Dim bDate as Date
bDate = CDate(VBA.Format(Me.lblCheckin.Caption,"dd-mm-yyyy"))
Do While CDate(arrTimeD(bIndex)) < bDate
If bIndex = lRow - 1 Then Exit Do
bIndex = bIndex + 1
Loop
When the user with US locale ("mm-dd") uses the spreadsheet, CDate(arrTimeD(bIndex)) throws error. CDate(VBA.Format(arrTimeD(bIndex))) and CDate(DateValue(arrTimeD(bIndex)) didn't help. What is the best way to do it?
Is it possible to set workbook's own date setting regardless of OS's?
Or I need to convert variant to string then concatenate?

Answer 1

The date string should be converted into a numeric date value.
Function DDMMYYYFormatToDateTimeValue(DateString As String) As Date
Dim Parts() As String
Parts = Split(DateString, "-")
DDMMYYYFormatToDateTimeValue = CDate(Parts(1) & "/" & Parts(0) & "/" & Parts(2))
End Function
Usage
Private Sub UserForm_Initialize()
Dim n As Long
For n = 1 To 100
ListBox1.AddItem Format(Date + n / 24, "MM-DD-YY HH:MM")
Next
End Sub
Public Function ListBoxDateValues()
Dim Data As Variant
ReDim Data(1 To Me.ListBox1.ListCount, 1 To 1)
Dim DateString As String
Dim r As Long
For r = 1 To Me.ListBox1.ListCount
DateString = Me.ListBox1.List(r - 1)
Data(r, 1) = DDMMYYYFormatToDateTimeValue(DateString)
Next
ListBoxDateValues = Data
End Function
Public Function wsLogs() As Worksheet
Set wsLogs = ThisWorkbook.Sheets("Logs")
End Function
Function DDMMYYYFormatToDateTimeValue(DateString As String) As Date
Dim Parts() As String
Parts = Split(DateString, "-")
DDMMYYYFormatToDateTimeValue = CDate(Parts(1) & "/" & Parts(0) & "/" & Parts(2))
End Function

Answer 2

First, true date values carry no format, so convert your text dates from the listbox directly to true date values:
.Cells(lRow + 1 + i, 10).Value = CDate(Me.ListBox1.List(i))
These you can apply the format you prefer for display.
The comparison is now straight:
Dim bDate As Date
bDate = CDate(Me.lblCheckin.Caption)
Do While arrTimeD(bIndex) < bDate
If bIndex = lRow - 1 Then
Exit Do
Else
bIndex = bIndex + 1
End If
Loop