PostMessage参数问题

[绿色盒子]

::PostMessage(hWnd,WM_MYMESSAGE,NULL,(LPARAM)&m_info);

我在线程中使用了PostMessage参数m_info使用类成员变量是可以的
但是不能为临时变量，如果是临时变量在消息响应函数中参数无法传递过来。
请问这是为啥？

[赵4老师]

PostThreadMessage
The PostThreadMessage function places (posts) a message in the message queue of the specified thread and then returns without waiting for the thread to process the message.

BOOL PostThreadMessage(
DWORD idThread, // thread identifier
UINT Msg, // message to post
WPARAM wParam, // first message parameter
LPARAM lParam // second message parameter
);

Parameters
idThread
Thread identifier of the thread to which the message will be posted.
The function fails if the specified thread does not have a message queue. The system creates a thread's message queue when the thread makes its first call to one of the Win32 USER or GDI functions. For more information, see the Remarks section.

Msg
Specifies the type of message to be posted.
wParam
Specifies additional message-specific information.
lParam
Specifies additional message-specific information.
Return Values
If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. To get extended error information, callGetLastError. GetLastError returns ERROR_INVALID_THREAD_ID if idThread is not a valid thread identifier, or if the thread specified by idThread does not have a message queue.

Remarks
The thread to which the message is posted must have created a message queue, or else the call to PostThreadMessage fails. Use one of the following methods to handle this situation:

Call PostThreadMessage. If it fails, call theSleep function and call PostThreadMessage again. Repeat until PostThreadMessage succeeds.
Create an event object, then create the thread. Use theWaitForSingleObject function to wait for the event to be set to the signaled state before calling PostThreadMessage. In the thread to which the message will be posted, call PeekMessage(&msg, NULL, WM_USER, WM_USER, PM_NOREMOVE) to force the system to create the message queue. Set the event, to indicate that the thread is ready to receive posted messages.
The thread to which the message is posted retrieves the message by calling the GetMessage or PeekMessage function. The hwnd member of the returned MSG structure is NULL.

QuickInfo
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Requires version 1.0 or later.
Header: Declared in winuser.h.
Import Library: Use user32.lib.
Unicode: Implemented as Unicode and ANSI versions on Windows NT.

See Also
Messages and Message Queues Overview, Message and Message Queue Functions,GetCurrentThreadId, GetMessage, GetWindowThreadProcessId, MSG, PeekMessage, PostMessage,Sleep,WaitForSingleObject

[绿色盒子]

引用 1 楼 赵4老师 的回复:

PostThreadMessage
The PostThreadMessage function places (posts) a message in the message queue of the specified thread and then returns without waiting for the thread to process the message.

BOOL PostThreadMessage(
DWORD idThread, // thread identifier
UINT Msg, // message to post
WPARAM wParam, // first message parameter
LPARAM lParam // second message parameter
);

Parameters
idThread
Thread identifier of the thread to which the message will be posted.
The function fails if the specified thread does not have a message queue. The system creates a thread's message queue when the thread makes its first call to one of the Win32 USER or GDI functions. For more information, see the Remarks section.

Msg
Specifies the type of message to be posted.
wParam
Specifies additional message-specific information.
lParam
Specifies additional message-specific information.
Return Values
If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. To get extended error information, callGetLastError. GetLastError returns ERROR_INVALID_THREAD_ID if idThread is not a valid thread identifier, or if the thread specified by idThread does not have a message queue.

Remarks
The thread to which the message is posted must have created a message queue, or else the call to PostThreadMessage fails. Use one of the following methods to handle this situation:

Call PostThreadMessage. If it fails, call theSleep function and call PostThreadMessage again. Repeat until PostThreadMessage succeeds.
Create an event object, then create the thread. Use theWaitForSingleObject function to wait for the event to be set to the signaled state before calling PostThreadMessage. In the thread to which the message will be posted, call PeekMessage(&msg, NULL, WM_USER, WM_USER, PM_NOREMOVE) to force the system to create the message queue. Set the event, to indicate that the thread is ready to receive posted messages.
The thread to which the message is posted retrieves the message by calling the GetMessage or PeekMessage function. The hwnd member of the returned MSG structure is NULL.

QuickInfo
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Requires version 1.0 or later.
Header: Declared in winuser.h.
Import Library: Use user32.lib.
Unicode: Implemented as Unicode and ANSI versions on Windows NT.

See Also
Messages and Message Queues Overview, Message and Message Queue Functions,GetCurrentThreadId, GetMessage, GetWindowThreadProcessId, MSG, PeekMessage, PostMessage,Sleep,WaitForSingleObject

我是发送到主窗口

[sdghchj]

PostThreadMessage
The PostThreadMessage function places (posts) a message in the message queue of the specified thread and then returns without waiting for the thread to process the message. 

简单说就是：异步执行消息，参数指针不能指向局部变量，因为局部变量销毁后，消息里的指针成了野指针。可以用指向堆内存。

[绿色盒子]

引用 4 楼 ForgetTomorrow 的回复:

用SendMessage可以

我试过了也不行

[绿色盒子]

引用 3 楼 sdghchj 的回复:

PostThreadMessage
The PostThreadMessage function places (posts) a message in the message queue of the specified thread and then returns without waiting for the thread to process the message. 

简单说就是：异步执行消息，参数指针不能指向局部变量，因为局部变量销毁后，消息里的指针成了野指针。可以用指向堆内存。

有道理

[ForgetTomorrow]

用SendMessage可以