Sub essai()
'-- simulation w() et y()
Dim w(1 To 31), y(1 To 3)
m = 1: an = 2018
For j = 1 To 31
w(j) = DateSerial(an, m, j)
Next j
y(1) = DateSerial(2018, 1, 2)
y(2) = DateSerial(2018, 1, 5)
y(3) = DateSerial(2018, 1, 8)
'--- différence z=w()-y()
Set d1 = CreateObject("scripting.dictionary")
For Each c In y(): d1(c) = "": Next c
Set d2 = CreateObject("scripting.dictionary")
For Each c In w
If Not d1.exists(c) Then d2(c) = ""
Next c
Z = d2.keys
[A1].Resize(, UBound(Z)) = Z
End Sub