Sub Bouton()
Dim str_temp As String
Dim tab_str_temp() As String
Dim iNbLigneDci As Integer
'iNbLigneDci = Application.WorksheetFunction.CountA(Columns(2)) - 1
iNbLigneDci = Range("R" & Rows.Count).End(xlUp).Row - 2
str_temp = Cells(i, "R")
For i = 3 To iNbLigneDci + 2
chaine = ""
tab_str_temp = Split(Cells(i, "R"), Chr(10))
For j = UBound(tab_str_temp) To 0 Step -1
chaine = Trim(tab_str_temp(j)) & Chr(10) & chaine
Next j
If str_temp = "" Then
i = i + 1
End If
Cells(i, "R") = Left(chaine, Len(chaine) - 1) 'on supprime le dernier retour chariot
Next i
End Sub