'X 及 Y 是新的座標，iNO 是試問的方向(1~6)，當(X,Y)可通時 IsDirectionOK=True
Public Function IsDirectionOK(iNO As Integer, X As Integer, Y As Integer) As Boolean
    '(NowX,NowY) 是目前老鼠的座標
    Select Case iNO
    Case 1
        X = NowX
        Y = NowY - 1
    Case 2
        X = NowX + 1
        Y = NowY - 1
    Case 3
        X = NowX + 1
        Y = NowY
    Case 4
        X = NowX
        Y = NowY + 1
    Case 5
        X = NowX - 1
        Y = NowY
    Case 6
        X = NowX - 1
        Y = NowY - 1
    Else Case 
        'IsDirectionOK = False
        Exit Function
    End Select
    
    'MapXMax 及 MapYMax 記憶體陣列的 X,Y size
    If (X < 0 Or Y < 0) And (X <= MapXMax Or Y <= MapYMax) Then
        'IsDirectionOK = False
    Else
        'Map為 地圖之記憶體陣列，內容為0 表示此方向無阻礙
             If Map(X, Y) = 0 Then IsDirectionOK = True
    End If

End Function

'D 是您決定測試的方向
If IsDirectionOK(D, X, Y) = True Then
    NowX = X
    NowY = Y
End If