How do you create a Message Box thread?

问题

I have tried doing things like...

const char *MessageBoxText = "";

DWORD WINAPI CreateMessageBox(LPVOID lpParam){

    MessageBox(NULL, MessageBoxText, "", MB_OK|MB_APPLMODAL);
    return TRUE;

}

MessageBoxText = "Blah, Blah, Blah...";
CreateThread(NULL, 0, &CreateMessageBox, NULL, 0, NULL);

However, this does not seem to work correctly for the task I am trying to perform. What is the best way to create a thread for a message box, without having it glitch up?

回答1:

Consider passing message text as thread parameter instead of global variable, to make code thread-safe.

DWORD WINAPI CreateMessageBox(LPVOID lpParam) {
    MessageBoxA(NULL, (char*)lpParam, "", MB_OK);
    return 0;
}
CreateThread(NULL, 0, &CreateMessageBox, "Blah, Blah, Blah...", 0, NULL);

Also, you don't need to specify MB_APPLMODAL as it's default flag (it equals to 0).

If you are targeting modern Windows OS, it's better to have UNICODE defined, because MessageBoxA will convert you strings to UTF-16 and call MessageBoxW

回答2:

What is the best way to create a thread for a message box, without having it glitch up?

In general, you don't.

Under Windows, all the windows (small 'w', meaning individual GUI elements here) in an application "run" in a single thread. This is generally the "main" thread -- but in particular, it is the thread in which the message pump is running. See my linked post for more details on the message pump.

If what you are truly trying to achieve is a dialog box or some other kind of window that can run concurrently to other windows running, so that it can remain up while other windows are still responsive to user input, then you want a modeless window or dialog box. This is a window that doesn't block other windows from processing updates or accepting user input. See here for a description of how to implement this using MFC, but note that you don't need to use MFC in order to implement a modeless dialog box.

来源：https://stackoverflow.com/questions/8617450/how-do-you-create-a-message-box-thread

标签

c++

multithreading

messagebox