voila mon code
Public Class Form1
Private Function Nvoyelle(ByVal Msg As String) As Integer
Dim i, N, z As Integer
Dim voy As String = "yeuoiz"
Len(Msg)
For i = 1 To Len(Msg)
z = Mid(Msg, i, 1)
If Trouvé (voy, z) <> 0 Then
N += 1
End If
Next i
Return N
End Function
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim M As String
M = TextA.Text
TextB.Text = CStr(Nvoyelle(M))
End Sub

je veu savoir qu'elle est l'equivalent des fonctions prédéfinis algorithmique len et mid et trouvé en vb.net
merci d'avance