C / C++ / MFC

Debojyoti Majumder12-Jan-11 19:44

Debojyoti Majumder

12-Jan-11 19:44

I am running my code in Winodws 7. I am using MessageBox() but it's not showing in the screen. The control is reaching there.

Andrew Brock12-Jan-11 20:00

12-Jan-11 20:00

This is a very vague description.
You could try setting the hWnd parameter to HWND_DESKTOP.
Or Open Spy++ (aka SpyXX) from the Vistual Studio Tools Menu. Then find your application window in the Windows page. The message box should be a child window of the window you provide to the hWnd parameter

Cool_Dev12-Jan-11 21:15

Cool_Dev

12-Jan-11 21:15

is it a windows service you are writing?

Getting logical drives of all Physical drives

Hamid_RT12-Jan-11 22:39

Hamid_RT

12-Jan-11 22:39

Whats the return value of MessageBox?

Of one Essence is the human race
thus has Creation put the base
One Limb impacted is sufficient
For all Others to feel the Mace
(Saadi )

learningvisualc12-Jan-11 19:03

learningvisualc

12-Jan-11 19:03

Hi all,

I have 2 hard disk in my system. I want to get Logical drives of both hard drives i.e. Physical drive 1 contains c: and e: partitions and Physical drive 2 contains d: f: and g: partitions. I have used this code to get the hard disk details.... but it is giving wrong result....

TCHAR szTemp[BUFSIZE];
    szTemp[0] = '\0';

    if (GetLogicalDriveStrings(BUFSIZE-1, szTemp)) 
    {
      TCHAR szName[MAX_PATH];
      TCHAR szDrive[MAX_PATH] = TEXT(" :");
      BOOL bFound = FALSE;
      TCHAR* p = szTemp;

      do 
      {
        // Copy the drive letter to the template string
        *szDrive = *p;

	
        // Look up each device name
        if (QueryDosDevice(szDrive, szName, BUFSIZE))
        {
			CString str = szDrive;
			str = str+szName;
			//strcat(szDrive , szName);
			m_Tree_Ctrl.InsertItem(str,root,TVI_LAST);
			//m_Tree_Ctrl.InsertItem("Physical Drive",root,TVI_LAST);		
        }

        // Go to the next NULL character.
        while (*p++);
      } while (!bFound && *p); // end of string
    }
	m_Tree_Ctrl.Expand(root,TVE_EXPAND);

It is making a tree like

Drives
C:\Device\Harddiskvolume1
D:\Device\Harddiskvolume2
E:\Device\Harddiskvolume3
.
.
.

I am not getting what exactly is the problem...

Can anybody help me in this...

Thanks in advance

Re: Getting logical drives of all Physical drives

Andrew Brock12-Jan-11 19:17

How can Terminate AfxbeginThread ?

12-Jan-11 19:17

This is a function in 1 of my utilities which does what i thiny you are wanting

#include <windows.h>
#include <stdio.h>

LPCSTR FormatSize(QWORD nSize) {
	static char szSize[16];
	if (nSize < 1024) {
		sprintf(szSize, "%uB", nSize);
	} else {
		char szScales[] = "KMGTPEZY";
		int nScale = 0;
		for (; nScale < sizeof(szScales); ++nScale) {
			if (nSize < 1024 * 1024) {
				sprintf(szSize, "%6.2f%cB", nSize / 1024.0f, szScales[nScale]);
				break;
			}
			nSize = (nSize + 512) / 1024;
		}
		if (nScale == sizeof(szScales)) {
			strcpy(szSize, "Unknown Size");
		}
	}
	return szSize;
}

void PrintDrives(char *szDrives) {
	DWORD nDrives = GetLogicalDrives();
	char szDrive[] = "A:\\";
	char szDriveName[MAX_PATH + 1];
	int nPrintedDrives = 0;
	while (nDrives != 0) {
		if (nDrives & 1) {
			szDrives[nPrintedDrives] = szDrive[0];
			GetVolumeInformation(szDrive, szDriveName, sizeof(szDriveName), NULL, NULL, NULL, NULL, 0);
			QWORD nAvaliable;
			QWORD nTotal;
			QWORD nFree;
			if (!GetDiskFreeSpaceEx(szDrive, (PULARGE_INTEGER)&nAvaliable, (PULARGE_INTEGER)&nTotal, (PULARGE_INTEGER)&nFree)) {
				nAvaliable = 0;
				nTotal = 0;
				nFree = 0;
			}
			if (*szDriveName == 0) {
				if (nTotal > 0) {
					printf("%s (%s)\n", szDrive, FormatSize(nTotal));
				} else {
					printf("%s (Unknown Size)\n", szDrive);
				}
			} else {
				if (nTotal > 0) {
					printf("%s (%s) [%s]\n", szDrive, FormatSize(nTotal), szDriveName);
				} else {
					printf("%s (Unknown Size) [%s]\n", szDrive, szDriveName);
				}
			}
		}
		nDrives >>= 1;
		++szDrive[0];
	}
}

int main(int argc, char *argv[]) {
	char szDrives[27];
	szDrives[26] = 0;
	PrintDrives(szDrives);
	return 0;
}

Le@rner12-Jan-11 18:39

12-Jan-11 18:39

How do I terminate a thread from outside of that thread.

My thread contains some function iand it takes some time to finish it .

i want when i send signal to stop thread its should stop immedeatily.

//To Run Thread I m using this.

CWinThread *Th;

// CTest_Thread CWinThread  derived class

Th = AfxBeginThread( RUNTIME_CLASS(CTest_Thread),THREAD_PRIORITY_NORMAL,0,CREATE_SUSPENDED,NULL);

if (NULL != Th)
{			
	Th >ResumeThread();
}

//To Stop Thread I m using this.

Th ->PostThreadMessage(WM_QUIT,NULL,NULL);

after using postthreadmessage to exit its not stop the thread immediately and its takes full time to perform thread functioning than stop and exit this.

so please tell me how can i stop the thread imeediately from outside of thread.

Andrew Brock12-Jan-11 18:58

12-Jan-11 18:58

You define your own custom message and then override CWinThread::PreTranslateMessage http://msdn.microsoft.com/en-US/library/67d74wsy(v=VS.80).aspx[^].

The thread intercepts messages before your main application does, so you cannot use WM_QUIT or other windows messages without affecting your application.

in the header file

#define CM_KILL_THREAD WM_USER + 0 //can go up to WM_USER + 0x7BFF

class CTest_Thread : public CWinThread {
	//other member functions and variables
	protected:
		virtual BOOL PreTranslateMessage(MSG *pMsg);
};

in the source file

BOOL CTest_Thread::PreTranslateMessage(MSG *pMsg) {
	if (pMsg->message == CM_KILL_THREAD) {
		ExitThread(0); //0 is the return code, if you need to send a message back to your application
		return TRUE; //I have procesed the message, nothing else needs to
	}
	return FALSE; //get something else to process the message
}

in your code

Th->PostThreadMessage(CM_KILL_THREAD, 0, 0);

Edit: corrected invalid indentation error

modified on Thursday, January 13, 2011 1:24 AM

Le@rner12-Jan-11 19:12

12-Jan-11 19:12

Andrew Brock wrote:
ExitThread(0); //0 is the return code, if you need to send a message back to your application
return TRUE; //I have procesed the message, nothing else needs to

BOOL CTest_Thread::PreTranslateMessage(MSG* pMsg)
{
	if (pMsg->message == ERR_KILL_THREAD) 
	{
		ExitThread(0); //0 is the return code, if you need to send a message back to your application
		return TRUE; //I have procesed the message, nothing else needs to
	}
	return FALSE; //get something else to process the message
	
	//return CWinThread::PreTranslateMessage(pMsg);
}

error on these line

1. error C2065: '' : undeclared identifier
2. error C2146: syntax error : missing ';' before identifier 'ExitThread'

modified on Thursday, January 13, 2011 1:18 AM

Andrew Brock12-Jan-11 19:24

12-Jan-11 19:24

It is an indentation problem... delete the 2 tabs infront of the ExitThread, then put them back, there is an invalid character hiding in there at the first character on the line

Le@rner12-Jan-11 19:26

12-Jan-11 19:26

thanks no compiling errors are resolved.

but i m stuck at this point.

i m using this inside the thread

CCriticalSection sec_s;
CSingleLock lock(&sec_s);

// Lock
lock.Lock();

//do something

// un Lock
lock.Unlock();

so thread not close immediately even after send message as you said.

modified on Thursday, January 13, 2011 1:58 AM

Andrew Brock12-Jan-11 20:35

12-Jan-11 20:35

Threads will very rarely close immediately after you tell it to. The reasons are too complex for me to explain here, but that isn't very important to this.
All that matters is that you wait for it to close. We do this with WaitForSingleObject http://msdn.microsoft.com/en-us/library/ms687032(v=vs.85).aspx[^], which will wait for almost anything that has a HANDLE

Th->PostThreadMessage(CM_KILL_THREAD, 0, 0);
switch (WaitForSingleObject(Th->m_hThread, 5000)) { //5000 = 5sec, this can be INFINITE, but if the thread never exits, then this will hang for ever
	case WAIT_OBJECT_0:
		TRACE("Thread terminated.\n");
		break;

	case WAIT_TIMEOUT:
		TRACE("Wait for terminate timed out.\n");
		//You may consider using TerminateThread here if you REALLY REALLY want the thread gone
		break;

	default:
		TRACE("WaitForSingleObject failed with error %d.\n", GetLastError());
		break;
}
//Now that the thread is gone, we can continue, say get the exit code that was passed to ExitThread()
DWORD nRetCode;
GetExitCodeThread(hRemoteThread, &nRetCode);

Be very careful with the earlier suggestion of TerminateThread, it can end badly. See http://msdn.microsoft.com/en-us/library/ms686717(v=vs.85).aspx[^] for more details

Le@rner12-Jan-11 20:40

12-Jan-11 20:40

once i use TerminateThread when i call this to terminate the thread my application is hanged and looks disabled and not respond ever after long time,so im scared and not want to to use TerminateThread,please tellme any other option or tell me where i can use WaitForSingleObject.

Andrew Brock12-Jan-11 20:58

12-Jan-11 20:58

That code I supplied earlier kills the thread by posting the CM_KILL_THREAD message that I showed you earlier and waits for it to terminate itself.
You may consider making it into a function like

DWORD KillThreadAndWait(CTest_Thread *pThread, DWORD nTimeoutMs = 5000) {
	HANDLE hThread = pThread->m_hThread;
	pThread->PostThreadMessage(CM_KILL_THREAD, 0, 0);
	switch (WaitForSingleObject(hThread, nTimeoutMs)) {
		case WAIT_OBJECT_0:
			TRACE("Thread terminated.\n");
			break;

		case WAIT_TIMEOUT:
			TRACE("Wait for terminate timed out.\n");
			return 0x80000000; //This can be anything that you can identify an error as.

		default:
			TRACE("WaitForSingleObject failed with error %d.\n", GetLastError());
			return 0x80000001; //This can be anything that you can identify an error as.
	}
	//Now that the thread is gone, we can continue, say get the exit code that was passed to ExitThread()
	DWORD nRetCode;
	GetExitCodeThread(hThread, &nRetCode);
	return nRetCode;
}

Then your code from earlier would look like

CTest_Thread *pThread;
pThread = (CTest_Thread *)AfxBeginThread(RUNTIME_CLASS(CTest_Thread), THREAD_PRIORITY_NORMAL, 0, CREATE_SUSPENDED, NULL);
if (pThread != NULL) {			
	pThread->ResumeThread();
}
TRACE("Thread exited with code 0x%08X\n", KillThreadAndWait(pThread, 5000));

Also, a correction from earlier, instead of using ExitThread, http://msdn.microsoft.com/en-us/library/s3w9x78e(v=vs.80).aspx says "To end the thread, call AfxEndThread from within the thread, or return from the controlling function of the worker thread."

BOOL CTest_Thread::PreTranslateMessage(MSG *pMsg) {
	if (pMsg-&gt;message == CM_KILL_THREAD) {
		//CORRECTION: MSDN says to use AfxEndThread when using AfxBeginThread to terminate the thread
		AfxEndThread(0); //0 is the return code, if you need to send a message back to your application
		return TRUE; //I have procesed the message, nothing else needs to
	}
	return FALSE; //get something else to process the message
}

EDIT: Corrected wrong variable name

modified on Thursday, January 13, 2011 3:17 AM

Le@rner12-Jan-11 21:17

12-Jan-11 21:17

what is hRemoteThread?

Andrew Brock12-Jan-11 21:21

12-Jan-11 21:21

Sorry, that was a copy and paste error from 1 of my own projects.
The code in the previous message has been corrected, I created the variable HANDLE hThread = pThread->m_hThread; as a shorthand.

Le@rner12-Jan-11 21:30

12-Jan-11 21:30

I place a breakpoint in CTest_Thread::PreTranslateMessage(MSG *pMsg) function ,but cursor never comes on this

Andrew Brock12-Jan-11 22:26

12-Jan-11 22:26

I would guess that you are overriding the Run() function, in which case the default CWinThread::Run() code won't be executed.
If you look at the default implementation in C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\atlmfc\src\mfc\thrdcore.cpp you will see that there is a message pump in it which will not be executed unless you manually execute it.

The Run() function is rarely overridden, however there are legitimate uses for it.
Depending on what you are trying to do, it may be possible to not override it, or to incorporate the message pump into your code.

Just note that you can't just exit a function when you tell it to quit... if it is waiting on data from the network, then it must receive that data or time out before the function returns

Le@rner12-Jan-11 23:13

12-Jan-11 23:13

No i m not overriding the Run() function.

Andrew Brock13-Jan-11 0:11

13-Jan-11 0:11

Do you have any code that waits on some external input before returning in the thread, such as keyboard input (scanf, _getch), network input (recv), exclusive handle (mutex, semaphore), ... that the thread might be hanging in?

If you insert a breakpoint on the switch (WaitForSingleObject(hThread, nTimeoutMs)), then when the breakpoint is hit change the thread (Thread Window is Debug>Windows>Threads) and change to your worker thread, then view the call stack (Call Stack window is Debug>Windows>Call Stack) to see if the thread may be stuck in a function when you are trying to send it the quit message.

Le@rner12-Jan-11 23:42

12-Jan-11 23:42

There is any minimum timeout value for WaitForSingleObject .

i mean use 5 sec for WaitForSingleObject or i can use less than 5 sec for WaitForSingleObject.

Andrew Brock12-Jan-11 23:56

12-Jan-11 23:56

You can use any value you like, even 0 for return immediately but then (in this case) what is the point, or you can make it as long as you want up to INFINITE.
I chose 5000ms because I thought it was a reasonable time to wait in this case.

Le@rner12-Jan-11 23:59