excel - VBA - How the colon `:` works in VBA code with condition

Question

The colon operator : is a statement delimiter in VBA.

However, does anyone has a clue why the first three examples work and the fourth (when uncommented) produces an error?

Option Explicit

Public Sub TestMe()

    If 1 = 1 Then: Debug.Print 1

    If 2 = 2 Then Debug.Print 2

    If 3 = 3 Then:
        Debug.Print 3

'   Gives error:
'    If 4 = 4 Then
'        Debug.Print 4

'Other Examples, from the comments and the answers:

::::::::::::::::::::::::::::         '<-- This seems to be ok

    If 5 = 5 Then Debug.Print "5a"::: Debug.Print "5b"
    If 6 = 0 Then Debug.Print "6a"::: Debug.Print "6b"

    If 7 = 0 Then:
        Debug.Print 7 ' Does not have anything to do with the condition...

    If 8 = 0 Then Debug.Print "8a"::: Debug.Print "8b" Else Debug.Print "8c"

End Sub

Answer 1

I think the confusion comes from 3. We'd think that 3 and 4 should behave the same. In fact, 3 is equivalent to this:

If 3 = 3 Then: (do nothing) 'an empty statement
   Debug.Print 3 ' <-- This will be executed regardless of the previous If condition

To see it, change 3 into this:

If 3 = 0 Then:
    Debug.Print 3 '<-- 3 will be printed! ;)

In conclusion, yes, the : is indeed to merge many statements on a single line

Good job @Vityata !!! :)