Sub macro12Mois()
Dim i As Byte, f
f = InputBox("Format du mois :" & Chr(13) & " 1:(Janvier), 2:(JANVIER), 3:(janvier)", "CREATION 12 FEUILLES", 1)
For i = 1 To 12
Sheets.Add after:=Sheets(i)
ActiveSheet.Name = _
CStr(Switch(f = 1, Application.Proper(MonthName(i)), f = 2, UCase(MonthName(i)), f = 3, MonthName(i)))
Next i
End Sub