For loop with variable ending integer - vba

Question

I have a dataset of 40,000 rows of data. My code is set so that it checks if the date in row n+1 is 1 day after the date in row n. If the dates in rows n and n+1 do not follow in normal chronological order, then it adds a row with blank data for that date.
My issues is that because I am adding rows along as I go, I have no idea what the ending range my for loop should have. I also tried just setting a really large range like "For n = 2 to 50000". But this gives me an overflow error.
Here is my code:
Sub MissingDates()
Dim n As Integer
Worksheets("sheet1").Activate
For n = 2 To 40000
If Cells(n, 2).Value <> Cells(n + 1, 2).Value - 1 Then
Cells(n + 1, 2).EntireRow.Insert Shift:=xlShiftDown
Cells(n + 1, 2) = Cells(n, 2) + 1
End If
Next
End Sub
Thank you in advance for any help.

Answer 1

A signed integer does not reach 40,000 and you should work from the bottom up.
Option Explicit
Sub MissingDates()
Dim n As Long, m As Long
With Worksheets("sheet1")
For n = .Cells(.Rows.Count, "B").End(xlUp).Row - 1 To 2 Step -1
For m = .Cells(n + 1, "B").Value2 - 1 To .Cells(n, "B").Value2 + 1 Step -1
.Cells(n + 1, 2).EntireRow.Insert Shift:=xlShiftDown
.Cells(n + 1, 2) = m
Next m
Next n
End With
End Sub

Answer 2

The overflow error comes because you declare n As Integer (i.e. 32,767) but you push it until 40,000. You can solve that by declaring n As Long instead.
As for your problem, you rather want a While loop instead of a For one. It should look something like this:
n = 2 '<- your starting value
Do While Cells(n+1,2).Value <> "" '<-- I guess you stop when there's no more value in your row
If Cells(n, 2).Value <> Cells(n + 1, 2).Value - 1 Then
Cells(n + 1, 2).EntireRow.Insert Shift:=xlShiftDown
Cells(n + 1, 2) = Cells(n, 2) + 1
End If
n = n + 1 '<-- increment n
Loop