Sub Rempl_Date()
Dim LeJour
Dim Jour_D As Byte
Dim Cel As Range
LeJour = Array("Lundi", "Mardi", "Mercredi", "Jeudi", "Vendredi", "Samedi", "Dimanche")
With Sheets("Feuil2")
For Each Cel In .Range("A3:A" & .Cells(Rows.Count, "A").End(xlUp).Row)
Jour_D = Application.Match(Application.Proper(Cel.Offset(, 3)), LeJour, 0) - 1
Cel.Offset(, 1) = 7 * Val(Mid(Cel, 5, 2)) + DateSerial(Right(Cel, 4) * 1, 1, 3) - _
Weekday(DateSerial(Right(Cel, 4) * 1, 1, 3)) - 5 + Jour_D
Next Cel
End With
End Sub