Identifying Length of Date Gap Given List of Dates - vba

Question

I am trying to write a script that searches a list of dates, and identifyies how long date gaps are. I'm new to VBA, and this may be completely wrong, but after referencing several sites, here is what I came up with:
Sub IdentifyGaps()
Dim startdate As Date 'first date in column
Dim enddate As Date 'last date in column
Dim ust As Date 'first date of unemployment
Dim i As Long
ust = ActiveCell.Offset(1, 0).Value
With Sheet6
startdate = [A1]
enddate = .Cells(.Rows.Count, "A").End(xlUp).Value
For i = startdate To enddate
If ust <> DateAdd("d", 1, i) Then
Sheet6.[C1].Value = DateDiff("d", i, ust)
End If
Next i
End With
End Sub
I'm not receiving an error, but the macro is not working properly. Right now, it's returning -43074 when it should be returning 15. Any help would be much appreciated!
Here is a screenshot of the data, with the lone date gap it should pick up.

Answer 1

Sub IdentifyGaps()
Dim ws As Worksheet
Dim Date1 As Long, Date2 As Long, Gap As Long, lRow As Long
Set ws = Sheet6
lRow = ws.Range("C" & Rows.Count).End(xlUp).Row
For x = 1 To ws.Range("A" & Rows.Count).End(xlUp).Row
Date1 = ws.Cells(x, 1).Value
Date2 = ws.Cells(x + 1, 1).Value
Gap = DateDiff("d", Date1, Date2)
If Gap > 1 Then
ws.Range("C" & lRow).Value = Gap
lRow = lRow + 1
End If
Next x

Answer 2

Looking at my calendar, I believe your expected result should actually be 17, not 15. This code will return the gap value as a Long value with which you can do whatever you want.
'Reads a column of dates and returns the length of the first gap found
Function IdentifyGaps() As Long
Dim StartDate As Date
Dim EndDate As Date
'This Variable is not needed for this solution, it is instead replaced by Gap
'Dim ust As Date
Dim Gap As Long
'Read cell values into an array for more efficient operation
Dim ReadArray() As Variant
ReadArray = Sheet6.Range("A1").CurrentRegion
Dim LastRow As Long
LastRow = UBound(ReadArray, 1)
StartDate = ReadArray(1, 1)
EndDate = ReadArray(LastRow, 1)
'ThisDate and PreviousDate are declared explicitly to highlight program flow
Dim Row As Long
Dim ThisDate As Date
Dim PreviousDate As Date
For Row = 2 To UBound(ReadArray, 1)
ThisDate = ReadArray(Row, 1)
PreviousDate = ReadArray(Row - 1, 1)
Gap = ThisDate - PreviousDate
If Gap > 1 Then Exit For
Gap = 0
Next Row
IdentifyGaps = Gap
End Function
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Sub ProveIt()
Debug.Print IdentifyGaps
End Sub