Question

So I’ve been trying to make a TicTacToe game for a programming class, and the teacher is useless. :l

When I run the program, 8 times out of 10; when I play and get the grid almost full, it freezes. It’s semi-difficult to explain, and I’m really tired. I hope someone can help. :s

Code:

    Private Sub ChooseBox()
    Dim num As Integer
    Dim Random As New Random
    num = Random.Next(0, 10)

    If Grid_1.Text <> "" And Grid_2.Text <> "" And Grid_3.Text <> "" And Grid_4.Text <> "" And Grid_5.Text <> "" And Grid_6.Text <> "" And Grid_7.Text <> "" And Grid_8.Text <> "" And Grid_9.Text <> "" Then
        gStatus = "Tie"
        Me.Text = "Tic Tac Toe - Nobody won!"
    Else
        If num = 1 And Grid_1.Text = "" Then
            Grid_1.Text = compChar : turnIs = "Player"
        ElseIf num = 2 And Grid_2.Text = "" Then
            Grid_2.Text = compChar : turnIs = "Player"
        ElseIf num = 3 And Grid_3.Text = "" Then
            Grid_3.Text = compChar : turnIs = "Player"
        ElseIf num = 4 And Grid_4.Text = "" Then
            Grid_4.Text = compChar : turnIs = "Player"
        ElseIf num = 5 And Grid_5.Text = "" Then
            Grid_5.Text = compChar : turnIs = "Player"
        ElseIf num = 6 And Grid_6.Text = "" Then
            Grid_6.Text = compChar : turnIs = "Player"
        ElseIf num = 7 And Grid_7.Text = "" Then
            Grid_7.Text = compChar : turnIs = "Player"
        ElseIf num = 8 And Grid_7.Text = "" Then
            Grid_8.Text = compChar : turnIs = "Player"
        ElseIf num = 9 And Grid_9.Text = "" Then
            Grid_9.Text = compChar
        Else : ChooseBox()
        End If
    End If
End Sub

Private Sub CheckResult()

    'First Column is filled
    If Grid_1.Text = compChar And Grid_2.Text = compChar And Grid_3.Text = compChar Then
        gStatus = "Won"
        Me.Text = "Tic Tac Toe - Computer Wins!"
    ElseIf Grid_1.Text = playerChar And Grid_2.Text = playerChar And Grid_3.Text = playerChar Then
        gStatus = "Won"
        Me.Text = "Tic Tac Toe - Player Wins!"
    End If

    'Second Column is filled
    If Grid_4.Text = compChar And Grid_5.Text = compChar And Grid_6.Text = compChar Then
        gStatus = "Won"
        Me.Text = "Tic Tac Toe - Computer Wins!"
    ElseIf Grid_4.Text = playerChar And Grid_5.Text = playerChar And Grid_6.Text = playerChar Then
        gStatus = "Won"
        Me.Text = "Tic Tac Toe - Player Wins!"
    End If

    'Third Column is filled
    If Grid_7.Text = compChar And Grid_8.Text = compChar And Grid_9.Text = compChar Then
        gStatus = "Won"
        Me.Text = "Tic Tac Toe - Computer Wins!"
    ElseIf Grid_7.Text = playerChar And Grid_8.Text = playerChar And Grid_9.Text = playerChar Then
        gStatus = "Won"
        Me.Text = "Tic Tac Toe - Player Wins!"
    End If

    'First Row is filled
    If Grid_1.Text = compChar And Grid_4.Text = compChar And Grid_7.Text = compChar Then
        gStatus = "Won"
        Me.Text = "Tic Tac Toe - Computer Wins!"
    ElseIf Grid_1.Text = playerChar And Grid_4.Text = playerChar And Grid_7.Text = playerChar Then
        gStatus = "Won"
        Me.Text = "Tic Tac Toe - Player Wins!"
    End If

    'Second Row is filled
    If Grid_2.Text = compChar And Grid_5.Text = compChar And Grid_8.Text = compChar Then
        gStatus = "Won"
        Me.Text = "Tic Tac Toe - Computer Wins!"
    ElseIf Grid_2.Text = playerChar And Grid_5.Text = playerChar And Grid_8.Text = playerChar Then
        gStatus = "Won"
        Me.Text = "Tic Tac Toe - Player Wins!"
    End If

    'Third Row is filled
    If Grid_3.Text = compChar And Grid_6.Text = compChar And Grid_9.Text = compChar Then
        gStatus = "Won"
        Me.Text = "Tic Tac Toe - Computer Wins!"
    ElseIf Grid_3.Text = playerChar And Grid_6.Text = playerChar And Grid_9.Text = playerChar Then
        gStatus = "Won"
        Me.Text = "Tic Tac Toe - Player Wins!"
    End If

    'Diagonal Upwards is filled
    If Grid_1.Text = compChar And Grid_5.Text = compChar And Grid_9.Text = compChar Then
        gStatus = "Won"
        Me.Text = "Tic Tac Toe - Computer Wins!"
    ElseIf Grid_1.Text = playerChar And Grid_5.Text = playerChar And Grid_9.Text = playerChar Then
        gStatus = "Won"
        Me.Text = "Tic Tac Toe - Player Wins!"
    End If

    'Diagonal Downwards is filled
    If Grid_3.Text = compChar And Grid_5.Text = compChar And Grid_7.Text = compChar Then
        gStatus = "Won"
        Me.Text = "Tic Tac Toe - Computer Wins!"
    ElseIf Grid_3.Text = playerChar And Grid_5.Text = playerChar And Grid_7.Text = playerChar Then
        gStatus = "Won"
        Me.Text = "Tic Tac Toe - Player Wins!"
    End If
End Sub

Answer 1

Three problems I see:

num = Random.Next(0, 10)

Random.Next is lower-bound inclusive and upper-bound exclusive. This means the computer can roll a 0 here. This won’t cause a loop, but it’s slightly wasteful since you never accept a 0 in your conditionals.

ElseIf num = 9 And Grid_9.Text = "" Then
    Grid_9.Text = compChar

Here, your pattern doesn’t include returning control to Player. I expect the computer would get two turns in this scenario.

ElseIf num = 8 And Grid_7.Text = "" Then
    Grid_8.Text = compChar : turnIs = "Player"

Now this is the likely loop problem. Notice when the computer rolls an 8 you’re checking grid 7 for contents. So if grid 8 is the last space, you will always fall through to another ChooseBox() call. The loop never resolves.