Out of stack space when using recursion in function - vba

Question

My function looks like this:
Sub sortNumbers()
Dim i As Integer
Dim j As Integer
Dim highestNumber As Integer
For i = 1 To 8
If IsEmpty(Cells(i + 4, 6).Value) = False Then
If Cells(i + 3, 6).Value > Cells(i + 4, 6).Value Then
highestNumber = Cells(i + 3, 6).Value
Cells(i + 3, 6).Value = Cells(i + 4, 6).Value
Cells(i + 4, 6).Value = highestNumber
End If
End If
Next i
For j = 1 To 8
If IsEmpty(Cells(j + 4, 6).Value) = False Then
If Cells(i + 3, 6).Value > Cells(i + 4, 6).Value Then
Call sortNumbers
Else
Exit Sub
End If
End If
Next j
End Sub
Everything gets sorted properly, but right after I get a message saying Out of stack space
Any help would be much appreciated!
EDIT
The excel sample data looks like this:
test data
1
100
1000
8
9
9
50
100
500
(from F3-F12)

Answer 1

If you remove the IsEmpty lines, Empty cells will be treated as 0. If you wish to leave them blank and sort around them you will need to impliment additional logic.
Your second loop needed to be adjusted. As it stood, the first time
call 1:
The first loop would give:
1 100 8 9 9 50 100 500 1000
Then the second loop would get to 1 > 100 and exit sub.
BUT... its best not to simply remove the exit sub call.
Its more efficient to only recall sortNumbers once per call.
If you had simply removed the exit sub.
then the second loop would get to 100 > 8 and trigger a recursion (Call 2).
Call 2:
the first loop would give:
1 8 9 9 50 100 100 500 1000
then the second loop would determine that Cells(i + 3,6) is never > Cells(i + 4,6) and exit Sub.
Since the 2nd call has returned we resume Call 1 where we left off. This means we finish the 2nd loop.
If this were a larger dataset you could have hundreds of recursions required to sort the dataset. When the last call (lets say its the 104th call) returns the previous 103 calls to the routine would all finish their 2nd loops (which since the 104th call returned, the data is already sorted, and thus is a waste)
The second loop should simply check to see if a recall is nessisary and if so, recall sortNumbers one time.
Sub sortNumbers()
Dim i As Integer
Dim j As Integer
Dim highestNumber As Integer
For i = 1 To 8
If Cells(i + 3, 6).value > Cells(i + 4, 6).value Then
highestNumber = Cells(i + 3, 6).value
Cells(i + 3, 6).value = Cells(i + 4, 6).value
Cells(i + 4, 6).value = highestNumber
End If
Next i
Dim ReCall As Boolean
ReCall = False
For i = 1 To 8
If Cells(i + 3, 6).value > Cells(i + 4, 6).value Then
ReCall = True
i = 8
End If
Next i
If ReCall Then Call sortNumbers
End Sub