vb.net - tic tac toe coding for tie

Question

I have a tic tac toe program and I've got everything working that way it should be. But, the one final problem I am having with this coding is that I can't seem to figure out when there is a tie how to code it. here is what i have so far.

Public Class Form1

Private turn As Integer = 1
Private play() As String = {"O", "X"}
Private board(2, 2) As String

Private Structure arrayIndex
    Dim x As Integer
    Dim y As Integer
End Structure

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    For x As Integer = 1 To 9
        Dim b As New Button With { _
            .Width = 80, _
            .Height = 80, _
            .Text = "", _
            .Location = New Point(60 + (((x - 1) Mod 3) * 80), 60 + (((x - 1)  3) * 80)), _
            .Tag = New arrayIndex With {.x = (x - 1) Mod 3, .y = (x - 1)  3}}
        Me.Controls.Add(b)
        AddHandler b.Click, AddressOf buttons_click

    Next
    Me.SetClientSizeCore(360, 360)

End Sub

Private Sub buttons_click(ByVal sender As System.Object, ByVal e As System.EventArgs)
    If DirectCast(sender, Button).Text <> "" Then Return
    DirectCast(sender, Button).Text = play(turn Mod 2)
    Dim index As arrayIndex = DirectCast(DirectCast(sender, Button).Tag, arrayIndex)
    board(index.x, index.y) = play(turn Mod 2)
    turn += 1
    winner()
End Sub

Private Sub winner()
    Dim rows(7) As String
    rows(0) = board(0, 0) & board(1, 0) & board(2, 0)
    rows(1) = board(0, 1) & board(1, 1) & board(2, 1)
    rows(2) = board(0, 2) & board(1, 2) & board(2, 2)
    rows(3) = board(0, 0) & board(0, 1) & board(0, 2)
    rows(4) = board(1, 0) & board(1, 1) & board(1, 2)
    rows(5) = board(2, 0) & board(2, 1) & board(2, 2)
    rows(6) = board(0, 0) & board(1, 1) & board(2, 2)
    rows(7) = board(2, 0) & board(1, 1) & board(0, 2)

    For x As Integer = 0 To 7
        If rows(x).Length = 3 AndAlso (rows(x)(0) = rows(x)(1) AndAlso rows(x)(0) = rows(x)(2)) Then
            If MessageBox.Show(rows(x)(0) & "'s winsssss!", "We have a winner!", MessageBoxButtons.OKCancel, MessageBoxIcon.Information) = DialogResult.OK Then
                turn = 1
                ReDim board(2, 2)
                For Each ctrl As Control In Controls
                    ctrl.Text = ""
                Next
                Return
            Else
                Me.Close()


            End If

        End If
    Next

End Sub


End Class

Answer 1

One way is that if all of the spaces are full and there is no winner, then there's a tie.