Sub test()
letColonne = InputBox("Indiquez la lettre de la colonne")
Dim cor As Range
Set cor = Range(Cells(1, 1), Cells(1, 16384))
'MsgBox cor.Count
'MsgBox Split(cor(1, 1).Address, "$")(1)
For i = 1 To cor.Count
If Split(cor(1, i).Address, "$")(1) = UCase(letColonne) Then
MsgBox letColonne
MsgBox i
Exit For
End If
Next i
End Sub