vb.net 出现对话框后如何停止我的程序执行
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How do I stop my program from executing after a dialog box appears
提问by Tyler Marshall
I have a problem where my code, a simple order form requires certain information. When the user does not enter a piece of information, the program displays a dialog box, and then after the user hits Okay, it still calculates the information. I am new to VB so here is the code snippet:
我的代码有问题，一个简单的订单需要某些信息。当用户没有输入一条信息时，程序会显示一个对话框，然后在用户点击“确定”后，它仍然计算信息。我是 VB 新手，所以这里是代码片段：
If (CheckBox3.Checked = False And blueBlackQuantityTextBox.Text <> "" And blueBlackQuantityTextBox.Text > 0) Then
MessageBox.Show("Please check item you wish to purchase", "No Item Selected",
MessageBoxButtons.OK, MessageBoxIcon.Error)
Stop
End If
Const whiteBlackDicePrice = 6.25
Const redBlackDicePrice = 5.0
Const blueBlackDicePrice = 7.5
Const tax = 0.05
Dim whiteBlackSubTotal As Double = whiteBlackQuantityTextBox.Text * whiteBlackDicePrice
Dim redBlackSubTotal As Double = redBlackQuantityTextBox.Text * redBlackDicePrice
Dim blueBlackSubtotal As Double = blueBlackQuantityTextBox.Text * blueBlackDicePrice
'newBalanceResultLabel.Text = String.Format("{0:C2}", newBalance)
Dim subtotal As Double = whiteBlackSubTotal + redBlackSubTotal + blueBlackSubtotal
whiteBlackTotalsLabel.Text = String.Format("{0:C2}", whiteBlackSubTotal)
redBlackTotalsLabel.Text = String.Format("{0:C2}", redBlackSubTotal)
blueBlackTotalsLabel.Text = String.Format("{0:C2}", blueBlackSubtotal)
subtotalResultLabel.Text = String.Format("{0:C2}", subtotal)
putting a STOP after each IF statement, results in the program crashing, and I can only have the dialog box say: Okay.
在每个 IF 语句后放置一个 STOP 会导致程序崩溃，我只能让对话框说：好的。
Please help!
请帮忙！
回答by T.S.
Here how you should write your program
在这里你应该如何编写你的程序
Private sub MySub()
If not ConditionsValidated() Then
MessageBox.Show("Please check item you wish to purchase") ' MsgBox with a single button always returns Ok. Here you don't even need to tell to show Ok - this is default.
Return
End If
' your code is running here
end sub
private function ConditionsValidated() as Boolean
' Validate your controls here
end sub
I would also NOT show "Error" message box if someone didn't select something. Error means your application encountered a serious error. This is why there are validators that could display a small red dot next to invalid control, or make back color of control red, etc
如果有人没有选择某些内容，我也不会显示“错误”消息框。错误意味着您的应用程序遇到了严重错误。这就是为什么有验证器可以在无效控件旁边显示一个小红点，或者使控件的背景颜色为红色等
回答by Khurram Shaikh
Simple Solution for this. Use below code at any place it will stop execution immediately.
对此的简单解决方案。在任何地方使用下面的代码它会立即停止执行。
Response.End
回答by ??ssa P?ngj?rdenlarp
If (CheckBox3.Checked = False And blueBlackQuantityTextBox.Text <> ""
And blueBlackQuantityTextBox.Text > 0) Then
If MessageBox.Show("Please check item you wish to purchase",
"No Item Selected",
MessageBoxButtons.OK, MessageBoxIcon.Error) = DialogResult.OK Then
Stop
End If
End if
The msgbox message and action dont seem to match. Its not clear that "No item" will END the program (or break to debug in the designer). Maybe you mean Exit Sub? Further, since they have one choice, OK, it will always end the program
msgbox 消息和操作似乎不匹配。不清楚“无项目”将结束程序（或中断以在设计器中进行调试）。也许你的意思是Exit Sub？更进一步，既然他们只有一个选择，好吧，它总是会结束程序
At any rate, MessageBoxis a function returning a DialogResultyou can evaluate. you dont have your configured that way
无论如何，MessageBox是一个返回一个DialogResult你可以评估的函数。你没有那样配置
