Sub conta_yap()
    Dim s As String, tot As Byte
    s = "fasfydpdafdaydpdafdayddpydpydpyp"
    tot = yap(s)
End Sub

Function yap(s As String) As Byte
    Dim i As Byte
    For i = 1 To Len(s) - 2
        If Mid(s, i, 3) Like "y?p" Then yap = yap + 1
    Next
End Function

Function yap(s As String) As Byte
    Dim i As Byte
    For i = 1 To Len(s) - 2
        If UCase(Mid(s, i, 3)) Like "Y?P" Then yap = yap + 1
    Next
End Function

Sub conta_yap()
  Dim s As String, tot As Long
  s = "FfgDgSAYapAFDffDSyEPFdfagfSDFDFAfgsdYiPDAFDYUPP"
  tot = REG(s)
End Sub

'necessita di libreria 'Microsoft VBScript Regular Expressions 5.5:
Function REG(s As String) As Long
  Dim REMatches As MatchCollection
  Dim RE As New RegExp

  With RE
    .MultiLine = True
    .Global = True
    .IgnoreCase = False
    .Pattern = "Y.P"
  End With

  Set REMatches = RE.Execute(UCase(s))
  REG = REMatches.Count

End Function

Option Explicit

Function find_yaps1(s As String) As Long
'soluzione 1: utilizzo di Mid, Left e Right
Dim i As Long, z As String, cnt As Long

    s = LCase(s)
    For i = 1 To Len(s) - 2
        z = Mid(s, i, 3)
        If Left(z, 1) = "y" And Right(z, 1) = "p" Then cnt = cnt + 1
    Next
    
    find_yaps1 = cnt
End Function


Function find_yaps2(s As String) As Long
'soluzione 1: utilizzo di Like
Dim i As Long, z As String, cnt As Long

    s = LCase(s)
    For i = 1 To Len(s) - 2
        z = Mid(s, i, 3)
        If z Like "y?p" Then cnt = cnt + 1
    Next
    
    find_yaps2 = cnt
End Function


Function find_yaps3(s As String) As Long
'soluzione 3: utilizzo delle regex (espressioni regolari)
Dim re As Object
    s = LCase(s)
    
    Set re = CreateObject("VBScript.RegExp")
    re.Pattern = "(?=(y.p))"
    
    re.IgnoreCase = True        'ignore case
    re.Global = True            'matches all occurances
    
    find_yaps3 = re.Execute(s).Count
End Function


Function find_yaps4(s As String)
'soluzione 4: array di byte
Dim i As Long, v() As String, b() As Byte, cnt As Integer, t As Long
    
    b() = LCase(s)
    For i = 0 To UBound(b) - 4 Step LenB("A")
        If b(i) = 121 And b(i + 4) = 112 Then cnt = cnt + 1  ' 121 = "y", 112 = "p"
    Next

    find_yaps4 = cnt
End Function


Sub test_find_yaps()
Dim s As String, m As String, i As Integer, j As Integer
Const NUM_TESTs = 4

    Debug.Print "Start ---------------------------------"
    For i = 1 To NUM_TESTs
        s = CStr(i)
        For j = 1 To 4
            Select Case j
            Case 1
                m = "yap"   'correct: 1
            Case 2
                m = "yypp"  'correct: 2
            Case 3
                m = "yaap"  'correct: 0
            Case 4
                m = "ayapo" 'correct: 1
            End Select
            Debug.Print "Running find_yaps" & s & ": yaps in '" & m & "'... " & Run("find_yaps" & s, m)
        Next j
        Debug.Print "- - - - - - - - - - - - - - - - - - - -"
    Next i
    Debug.Print "End -----------------------------------"
End Sub