Sub dateFormat()
Dim ligneFichier As Long
ligneFichier = Sheets(1).Range("A65536").End(xlUp).Row
Columns("C:C").Select
Selection.NumberFormat = "dd/mm/yyyy"
For i = 2 To ligneFichier
maDate = Sheets(1).Range("A" & i).Value
maDate = Format(maDate, "dd/mm/yyyy")
Range("C" & i).Value = maDate
Next i
End Sub