Sub Convertir()
Dim DtHr(), Conv(), i&, n&, s
With [A1] 'Entête de la colonne de données
n = .Parent.Cells(.Parent.Rows.Count, .Column).End(xlUp).Row
If n > .Row Then
DtHr = .Parent.Range(.Cells, .Parent.Cells(n, .Column)).Value
n = n + 1 - .Row
ReDim Conv(2 To n, 0)
On Error Resume Next
For i = 2 To n
s = Split(DtHr(i, 1), "/")
Conv(i, 0) = CDate(Join(Array(s(1), s(0), s(2)), "/"))
Next
With .Offset(1, 1)
.Resize(n - 1, 1).Value = Conv
.EntireColumn.AutoFit
End With
End If
End With
End Sub