请问wm_drivechang的详细用法！(30分)

如题，特别是它的各个返回参数是什么意思！

没听说过，哪来的？

我也想知道！<br>希望大家多灌水

怎么无人回答我？

wm_drivechang哪里有这个参数????

应该是wm_devicechange.

没有这样一个消息。

怎么没有人回答？不是这个问题难度好高吧！

怎么别人都不知道这个消息?你在哪里看到的?

怎么没有人为我答这个问题呵？？？

来自：wjiachun 时间：00-10-17 21:40:07 ID:368461 &nbsp;<br>&nbsp;怎么别人都不知道这个消息?你在哪里看到的?<br>&nbsp;<br>&nbsp;<br>

我已经忘了在那里看到的了。

The WM_DEVICECHANGE device message notifies an application or device driver of a change to the hardware configuration of a device or the computer.<br><br>Event = (UINT) wParam;<br>dwData = (DWORD) lParam;<br>&nbsp; <br><br>Parameters<br><br>Event<br><br>Event type. This parameter can be one of the following values:<br><br>Value Meaning<br>DBT_CONFIGCHANGECANCELED A request to change the current configuration (dock or undock) has been canceled.<br>DBT_CONFIGCHANGED The current configuration has changed, due to a dock or undock. <br>DBT_DEVICEARRIVAL A device has been inserted and is now available. <br>DBT_DEVICEQUERYREMOVE Permission is requested to remove a device. Any application can deny this request and cancel the removal.<br>DBT_DEVICEQUERYREMOVEFAILED A request to remove a device has been canceled.<br>DBT_DEVICEREMOVECOMPLETE A device has been removed.<br>DBT_DEVICEREMOVEPENDING A device is about to be removed. Cannot be denied.<br>DBT_DEVICETYPESPECIFIC A device-specific event has occurred.<br>DBT_QUERYCHANGECONFIG Permission is requested to change the current configuration (dock or undock). <br>DBT_USERDEFINED The meaning of this message is user-defined.<br>&nbsp;<br><br>dwData<br><br>Address of a structure that contains event-specific data. Its meaning depends on the given event.<br><br>&nbsp;<br><br>Return Values<br><br>Return TRUE to grant a requested action.<br>Return QUERY_BROADCAST_DENY to deny a requested action.<br><br>Remarks<br><br>For devices that offer software-controllable features, such as ejection and locking, the operating system typically sends a DBT_DEVICEREMOVEPENDING message to let applications and device drivers end their use of the device gracefully. <br>If the operating system forcibly removes a device, it may not send a DBT_DEVICEQUERYREMOVE message before doing so.<br>DBT_CONFIGCHANGECANCELED, DBT_CONFIGCHANGED, DBT_DEVICEARRIVAL, DBT_DEVICEQUERYREMOVE, DBT_DEVICEQUERYREMOVEFAILED, DBT_DEVICEREMOVECOMPLETE, DBT_DEVICEREMOVEPENDING, DBT_DEVICETYPESPECIFIC, DBT_QUERYCHANGECONFIG, DBT_USERDEFINED

不好意思,我还有一个问题!一并问了吧!<br><br>我在使用这个函数时,已经使CDROM打开了,<br>这样使用:<br>procedure tform1.wmdevicechange(var msg:tmessage);<br>begin<br>&nbsp;if msg.wparam=DBT_DEVICEREMOVEPENDING then<br>&nbsp; &nbsp; msg.result:=true;<br>而delphi5系统却是报出错,DBT_DEVICEREMOVEPENDING 出现什么错误!<br>我已经在开头声明了这个函数了!<br><br>希望大家能给我一个解答,谢谢!<br>

怎么等了这么多天,还是没有人回答我呵!<br><br>高手们能不能快点,我正等着用呢,先谢谢了!

接受答案了.