C++ 以编程方式退出 MFC 应用程序的正确方法是什么？
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What is the correct way to programmatically quit an MFC application?
提问by User
Using windows MFC C++. I have a third party app that calls a user-defined method in my CWinApp derived class. This method is called after InitInstance(). If there is an error in this method, such that an exception is thrown and caught in a try/catch block, I would like to exit the application from the catch block. What is the canonical and correct way to quit?
使用 Windows MFC C++。我有一个第三方应用程序，它在我的 CWinApp 派生类中调用用户定义的方法。该方法在 InitInstance() 之后调用。如果此方法中存在错误，从而引发异常并在 try/catch 块中捕获，我想从 catch 块中退出应用程序。什么是规范和正确的戒烟方式？
UPDATE:
更新：
Serge I believe is right that in InitInstance() returning false is the correct way to quit the application. However, now suppose I want to quit from a CDialog derived class's OnInitDialog() handler, what's the correct way to do that.
Serge 我认为在 InitInstance() 中返回 false 是退出应用程序的正确方法是正确的。但是，现在假设我想退出 CDialog 派生类的 OnInitDialog() 处理程序，那么正确的方法是什么。
UPDATE 2
更新 2
For me, I found calling PostMessage(WM_CLOSE) to be the best way from my non-modal CDialog derived class. All other methods of quitting I tried would raise some exception or other in some circumstances.
对我来说，我发现调用 PostMessage(WM_CLOSE) 是我的非模态 CDialog 派生类的最佳方法。在某些情况下，我尝试过的所有其他退出方法都会引发一些异常或其他异常。
Here's an example of how I use it:
这是我如何使用它的示例：
BOOL SomeDialog::OnInitDialog()
{
CDialog::OnInitDialog();
::OleInitialize(nullptr);
try
{
// ...load settings file here
}
catch(...)
{
PostMessage(WM_CLOSE);
return TRUE;
}
// return TRUE unless you set the focus to a control
return TRUE;
}
回答by Serge Wautier
In InitInstance()
在 InitInstance()
Exiting the app while you are still in InitInstance(): Simply return FALSEfrom InitInstance().
在您仍在时退出应用程序InitInstance()：只需FALSE从InitInstance().
In the main message loop
在主消息循环中
It's another story though if you are already in the message loop: The standard way to close an app is to exit the message loop:
如果您已经在消息循环中，那就是另一回事了：关闭应用程序的标准方法是退出消息循环：
PostQuitMessage(0), as its name implies, posts a WM_QUITmessage. The message loop reacts by exiting the loop and closing the program.
PostQuitMessage(0)，顾名思义，发布WM_QUIT消息。消息循环的反应是退出循环并关闭程序。
But you shouldn't simply do that: You should close the opened windows in your app. Assuming you have only your main window, you should destroy it by calling
但您不应该简单地这样做：您应该关闭应用程序中打开的窗口。假设你只有你的主窗口，你应该通过调用来销毁它
m_pMainWindow->DestroyWindow();
MFC will react by PostQuitMessage()for you, hence exit the main message loop and close your app.
MFC 将为PostQuitMessage()您做出反应，因此退出主消息循环并关闭您的应用程序。
Better yet, you should post a WM_CLOSEto let your main window close gracefully. It may for example decide to save the current document. Beware though: the standard OnClose()handler may prompt user to save dirty documents. User can even cancel the close action using this prompt (Save document? Yes, No, Cancel).
更好的是，你应该发布一个WM_CLOSE让你的主窗口优雅地关闭。例如，它可以决定保存当前文档。但要注意：标准OnClose()处理程序可能会提示用户保存脏文档。用户甚至可以使用此提示取消关闭操作（保存文档？是、否、取消）。
Destroying the main window will post a WM_DESTROYmessage to it. MFC reacts by calling PostQuitMessage(0)to exit the message pump. (Actually, MFC does the call in OnNcDestroy()since WM_NCDESTROYwhich is the absolute last mesage received by a window)
销毁主窗口将WM_DESTROY向其发布一条消息。MFC 通过调用PostQuitMessage(0)退出消息泵来做出反应。（实际上，MFC 会调用 inOnNcDestroy()因为WM_NCDESTROY这是窗口收到的绝对最后一条消息）
Dialog-based app
基于对话框的应用程序
Call EndDialog(-1);// Or replace -1 by IDCANCEL, whatever
调用EndDialog(-1);// 或者用 替换 -1 IDCANCEL，随便
This call, as you probably know, will close the dialog.
您可能知道，此调用将关闭对话框。
Note that the main dialog of dialog-based app executes in InitInstance(). Closing the dialog will simply exit InitInstance(), which always returns FALSEin such projects.
请注意，基于对话框的应用程序的主对话框在 InitInstance() 中执行。关闭对话框将简单地 exit InitInstance()，它总是FALSE在此类项目中返回。
回答by leetNightshade
Simply use:
只需使用：
PostQuitMessage(0);
Keep in mind your program won't quit instantly from this call, the window/program will receive a WM_QUIT message and then your program will quit.
请记住，您的程序不会从此调用立即退出，窗口/程序将收到 WM_QUIT 消息，然后您的程序将退出。
回答by zar
Serge - your answer is unfortunately not the best way to do it. PostQuitMessage(0) is the way to go and MFC will destroy the windows for you. You should avoid calling m_pMainWindow->DestroyWindow() directly.
Serge - 不幸的是，您的回答不是最好的方法。PostQuitMessage(0) 是要走的路，MFC 会为您销毁窗口。您应该避免直接调用 m_pMainWindow->DestroyWindow()。
