Remplacement de chaine

Sub test()
x = Selection.Row
y = Selection.Column
While Cells(x, y) <> ""
 If Left(CStr(Cells(x, y)), 2) = "23" Then
    Cells(x, y) = "23xxx"
 End If
 x = x + 1
Wend
End Sub

Sub XXX_23()
Dim Tablo, k As Long
Tablo = Sheets("Feuil1").Range("A1:A" & Sheets("Feuil1").Range("A65536").End(xlUp).Row)
  For k = LBound(Tablo) To UBound(Tablo)
    If Left(Tablo(k, 1), 2) = "23" Then Tablo(k, 1) = "23XXX" 
  Next
Sheets("Feuil1").Range("A1:A" & Sheets("Feuil1").Range("A65536").End(xlUp).Row) = Tablo
End Sub

Sub Macro1()
Selection.Replace What:="23?*", Replacement:="23XXX", LookAt:=xlWhole, SearchOrder:=xlByRows, MatchCase:=True
End Sub

Sub Macro1_b()
Dim a$, b$, r As Range
a = InputBox("Chaine recherchée?", "Choix", 23)
b = a & "XXX"
Set r = Range([A1], [A65536].End(xlUp))
r.Replace a & "?*", b, xlWhole, xlByRows, True
Set r = Nothing
End Sub