Vb.net 蛇和梯子

我必须为一个项目创建一个蛇和梯子游戏。我的棋盘上有30个空格。如果标记超过30，应用程序将崩溃：

appCounter.exe中发生“System.NullReferenceException”类型的未处理异常

其他信息：对象引用未设置为对象的实例。“

如果滚动的数字超过30，我希望标记保持在原来的位置

这是我的密码：

Public Class frmBoard
Dim intScore As Integer

Private Sub btnOK_Click(sender As Object, e As EventArgs) Handles btnOK.Click
    'declartions
    Dim intValue As Integer
    Dim strCounterName As String
    Dim roll As New Random()
    Dim intRoll = roll.Next(1, 7)

    'make the current counter visible
    If intScore > 0 Then
        strCounterName = "lblCounter" & intScore
        Me.Controls(strCounterName).Visible = False
    End If


    'input
    intValue = intRoll
    intScore = intScore + intValue
    strCounterName = "lblcounter" & intScore.ToString

    'output
    txtMove.Text = intRoll
    Me.Controls(strCounterName).Visible = True

    If intScore = 3 Then
        lblCounter3.Visible = False
        lblCounter22.Visible = True
        intScore = 22
    End If

    If intScore = 5 Then
        lblCounter5.Visible = False
        lblCounter8.Visible = True
        intScore = 8
    End If

    If intScore = 11 Then
        lblCounter11.Visible = False
        lblCounter26.Visible = True
        intScore = 26
    End If

    If intScore = 20 Then
        lblCounter20.Visible = False
        lblCounter29.Visible = True
        intScore = 29
    End If

    If intScore = 17 Then
        lblCounter17.Visible = False
        lblCounter4.Visible = True
        intScore = 4
    End If

    If intScore = 19 Then
        lblCounter19.Visible = False
        lblCounter7.Visible = True
        intScore = 7
    End If

    If intScore = 21 Then
        lblCounter21.Visible = False
        lblCounter9.Visible = True
        intScore = 9
    End If

    If intScore = 27 Then
        lblCounter27.Visible = False
        lblCounter1.Visible = True
        intScore = 1
    End If

    If intScore = 31 Then
        lblCounter31.Visible = False
        lblCounter1.Visible = True
        intScore = 1
    End If

    If intScore = 32 Then
        lblCounter32.Visible = False
        lblCounter1.Visible = True
        intScore = 1
    End If

    If intScore = 33 Then
        lblCounter33.Visible = False
        lblCounter1.Visible = True
        intScore = 1
    End If

    If intScore = 30 Then
        MsgBox("Winner")
    End If

    If intScore > 30 Then
        MsgBox("OvErBoArD")
    End If
    End Sub


End Class

---

由于intScore超过30时只有30个计数器，因此将抛出此异常

将If语句添加到输入中，如下所示：

'input
intValue = intRoll
If intscore + intvalue < 30 then 
intscore=intscore + intvalue
End if

strCounterName = "lblcounter" & intScore.ToString

”输入
intValue=intRoll
如果intscore+intvalue<30，则
intscore=intscore+intvalue
如果结束
strCounterName=“lblcounter”&intScore.ToString

---

这样，在设置LBL计数器之前，它不会超过30，也不会出现故障

这将向用户显示他们已经检查过，并跳过将滚动添加到总数中，以使其保持原位

更改：

'input
intValue = intRoll
intScore = intScore + intValue
strCounterName = "lblcounter" & intScore.ToString

致：

---

请注意，

vba

与

vb.net

不同。当您添加用户的“掷骰子”时，您需要添加一些检查，以查看

如果掷骰子+积分>30，则

不要使用计数器，

否则将掷骰子添加到计数器中

。我对这一点不熟悉，我的老师没有太多的解释，抱歉，比约恩除非这是你唯一要写的东西，否则这不会是你第一次遇到NRE。链接上的VB答案可能会有所帮助。这不符合用户的标准“如果滚动的数字超过30，我希望标记保持在原来的位置。”谢谢！这工作做得很好！

'input
intValue = intRoll
If intScore + intValue > 30 Then
    MsgBox "OvErBoArD"
Else
    intScore = intScore + intValue
End If
strCounterName = "lblcounter" & intScore.ToString