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Use your debugger to track down the problem. You're probably writing to an invalid pointer.
paras_s12 wrote: pplease solve this
Giving the poor information you give, that will be really hard.
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thanks a lot sir
my code is this
i use debugger but i can not find sloution sir
void CCompanyDlg::OnConnect()
{
int i;
MYSQL *myDB;
MYSQL_RES *res;
MYSQL_ROW row;
CString user,pass,aqp;
if ((myDB = mysql_init((MYSQL*) 0)) &&
mysql_real_connect(myDB,"localhost","root",NULL,NULL,3306,NULL,NULL))
{
if ( mysql_select_db( myDB,"gourav") < 0 )
{
MessageBox("Can't select the database !\nTry later.");
goto exit_here;
}
else
{
MessageBox("Can't connect !\nPlease try later.") ;
goto exit_here;
}
}
GetDlgItemText(IDC_USER,user);
GetDlgItemText(IDC_PASS,pass);
if(!mysql_query(myDB,"SELECT id from login WHERE user= \'" + user + "\' "))
res=mysql_store_result(myDB);
row = mysql_fetch_row(res);
{
i = (int) mysql_num_rows( res );
if (i != 1)
{
MessageBox("WRONG LOGIN PLEASE TRY AGAIN", " aq ",MB_ICONASTERISK);
mysql_free_result( res ) ;
goto exit_here;
}
}
switch(atoi(*row))
{
case 0: // regular user
{
CAdmin dlg;
dlg.DoModal();
UpdateData(FALSE);
}
break;
case 1: // administrator
{
CManager dlg1;
dlg1.DoModal();
UpdateData(FALSE);
}
break;
}
exit_here:
mysql_close( myDB);
}
hi
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Where does it crashes ? If the debugger doesn't show your code, use the callstack to locate the problem more precisely.
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when i use debugger then it will not show error in code
and in stack it show libmysql.dll with some no and nothing else sir
thanks![Rose | [Rose]](https://www.codeproject.com/script/Forums/Images/rose.gif)
hi
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set a breakpoint an watch your variables...
if you use/pass a null pointer, that's probably a thing to investigate...
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Well, you could at least read what I've posted:
If the debugger doesn't show your code, use the callstack to locate the problem more precisely.
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thanks 100 times sir
aqp ="SELECT id from login WHERE user= \'" + user + "\' ";
this query does not return value to aqp
i dont know why
can u tell me please
bye
hi
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I really don't see how it make your application crash !
Did you do what I asked ? Meaning start your debugger, look at the call stack to see where exactly in your code the problem comes from. Then, at this point you can watch the different variables and see if they are what you expect them to be. You can also put breakpoints before and check step by step if everything goes as expected.
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posting a huge code, not even formatted will certainly not help you but will give people a bad thinking of you.
Cédric Moonen told you to use your debugger... did you try even to ?
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paras_s12 wrote: i use debugger...
How exactly? Did you single-step through this code snippet?
"A good athlete is the result of a good and worthy opponent." - David Crow
"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne
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Is there any method known which can list all directories from an filepath.
E.g.
c:\dir1\dir2\dir3\name.abc -> directories are: dir1, dir2 and dir3?
Anything, using loops or something else?
Thanks for help!
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Call FindFirstFile with c:\dir1\dir2\dir3\name.abc and an empty WIN32_FIND_DATA variable as parameter. Your WIN32_FIND_DATA variable.cFileName will give you the first matching file name. Then you can call FindNextFile in a while loop for subsequent matches. Use the same WIN32_FIND_DATA variable as a parameter to FindNextFile. (Looping through FindNextFile is required if you are searching using wildcards, like C:\Temp\*.*)
Refer http://msdn2.microsoft.com/en-us/library/aa365200.aspx[^] for complete example.
One more thing to take care, if you search for *.*, then the first two matches will be . and .. respectively, so you may choose to ignore them.
It's better to know some of the questions than all of the answers.
Pravin.
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You'll want to use PathFindNextComponent().
"A good athlete is the result of a good and worthy opponent." - David Crow
"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne
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See DlgDirList does any help?
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Hi everyone,
When I use Instance Subclassing technique, SetWindowLong() or SetWindowLongPtr() returns NULL pointer. The last error is 50 ERROR_NOT_SUPPORT. I ran the same program on more than 10 XP machines. One of them failed. Does anybody here encounter such problem? Any suggestion?
Thank you in advanced
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From the SetWindowLongPtr documentation:
"If the previous value is zero and the function succeeds, the return value is zero, but the function does not clear the last error information. To determine success or failure, clear the last error information by calling SetLastError(0), then call SetWindowLongPtr. Function failure will be indicated by a return value of zero and a GetLastError result that is nonzero."
The only cases in which these functions should fail are if you pass an invalid window handle, or if you pass an invalid index value (more than the number of bytes associated with the window, or not one of the defined GWL/GWLP values).
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Hi!
Good day 
I have this problem about synchronization on namedpipe ...
I have this namedpipe server that allows multiple instances.
The algorithm I have is I'll wait for a client to connect to the namedpipe then spawn a thread which will read the message from the namedpipe. My expectation on the spawned thread is that when the client has disconnected the spawned thread will end also. But when I tried testing my code, the thread count keeps on increasing due to the spawned thread, which i think means I was not able to detect that the client had disconnected or something else 
Any help is greatly appreciated.
Below are my codes:
1. Createnamedpipe, wait for a client to connect, and spawned a thread.
<br />
UINT fnRcvMsgsFrmNamedpipeThread(LPVOID pParam)<br />
{<br />
<br />
DWORD dwResult = SUCCEED; <br />
CString strLog( _T( "" ) );<br />
<br />
OVERLAPPED stClientConnectOverLap = {0};<br />
stClientConnectOverLap.hEvent = CreateEvent(<br />
NULL,
TRUE,
FALSE,
NULL);
<br />
if( stClientConnectOverLap.hEvent == NULL )<br />
{<br />
return 0;<br />
}<br />
<br />
HANDLE hEvents;<br />
hEvents = stClientConnectOverLap.hEvent;<br />
<br />
CString strFormatPipeName( _T( "" ) );<br />
strFormatPipeName.Format( "\\\\%s\pipe\mypipename", STR_PERIOD );<br />
<br />
HANDLE hClientReqPipe;<br />
<br />
while ( TRUE )<br />
{<br />
hClientReqPipe = CreateNamedPipe( strFormatPipeName,<br />
FILE_FLAG_OVERLAPPED | PIPE_ACCESS_DUPLEX, PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT,<br />
PIPE_UNLIMITED_INSTANCES, <br />
0, 0, 10000, NULL ); <br />
if( hClientReqPipe == INVALID_HANDLE_VALUE )<br />
{ <br />
dwResult = GetLastError();<br />
break;<br />
}<br />
<br />
if( !ConnectNamedPipe( hClientReqPipe, &stClientConnectOverLap ) )<br />
{<br />
if( GetLastError() != ERROR_PIPE_CONNECTED )<br />
{<br />
DWORD dwRet = WaitForSingleObject( hEvents, INFINITE );<br />
if( dwRet != WAIT_OBJECT_0 )<br />
{<br />
dwResult = GetLastError();<br />
break;<br />
}<br />
}<br />
<br />
}<br />
CWinThread *pReadMsgThread = AfxBeginThread( fnReadMsgFrmNamedpipe, (LPVOID) hClientReqPipe );<br />
if( NULL == pReadMsgThread )<br />
{<br />
break;<br />
}<br />
<br />
}<br />
<br />
::CloseHandle( hClientReqPipe );<br />
::CloseHandle( stClientConnectOverLap.hEvent );<br />
<br />
return dwResult;<br />
}<br />
2. Spawned thread
<br />
UINT fnReadMsgFrmNamedpipe(LPVOID pParam)<br />
{ <br />
I32L dwResult = SUCCEED; <br />
CString strLog( _T("") );<br />
HANDLE hClientReqPipe = (HANDLE) pParam;<br />
<br />
OVERLAPPED stClientRecOverLap = {0};<br />
<br />
stClientRecOverLap.hEvent = CreateEvent( NULL,
TRUE,
FALSE,
NULL );
<br />
if( stClientRecOverLap.hEvent == NULL )<br />
{<br />
return 0;<br />
}<br />
<br />
HANDLE hEvents;<br />
hEvents = stClientRecOverLap.hEvent;<br />
<br />
DWORD dwTotalByte, dwRead, dwRet;<br />
<br />
while ( TRUE )<br />
{ <br />
dwTotalByte = 0;<br />
dwRead = 0;<br />
<br />
ReadFile( hClientReqPipe, NULL, 0, &dwRead, &stClientRecOverLap );<br />
dwRet = WaitForSingleObject( hEvents, INFINITE );<br />
<br />
if( dwRet != WAIT_OBJECT_0 )<br />
{<br />
dwResult = GetLastError();<br />
break;<br />
}<br />
if( !PeekNamedPipe( hClientReqPipe, NULL, 0, NULL, &dwTotalByte, NULL ) )<br />
{<br />
dwResult = GetLastError();<br />
break;<br />
}<br />
<br />
if( dwTotalByte > 0 )<br />
{<br />
char* pBuffer = new char[ dwTotalByte + 1 ];<br />
if( !pBuffer )<br />
{<br />
continue; <br />
}<br />
::ZeroMemory( pBuffer, dwTotalByte + 1 );<br />
<br />
ReadFile( hClientReqPipe, pBuffer, dwTotalByte, &dwRead, &stClientRecOverLap );<br />
dwRet = WaitForSingleObject( stClientRecOverLap.hEvent, 10000 );<br />
if( dwRet != WAIT_OBJECT_0 )<br />
{<br />
dwResult = GetLastError();<br />
break;<br />
}<br />
<br />
delete pBuffer;<br />
<br />
}<br />
}<br />
<br />
DisconnectNamedPipe( hClientReqPipe );<br />
CloseHandle( stClientRecOverLap.hEvent );<br />
return dwResult;<br />
}<br />
3. Namedpipe Client
<br />
BOOL fnNewConnectNamedPipe(LPCTSTR lpczPipeName)<br />
{<br />
HANDLE hPipe; <br />
<br />
while (TRUE)<br />
{<br />
hPipe = CreateFile( <br />
lpczPipeName,
GENERIC_READ |
GENERIC_WRITE, <br />
0,
NULL,
OPEN_EXISTING,
0,
NULL);
<br />
<br />
if (hPipe != INVALID_HANDLE_VALUE) <br />
break; <br />
<br />
<br />
if (GetLastError() != ERROR_PIPE_BUSY) <br />
{<br />
printf("Could not open pipe"); <br />
return FALSE;<br />
}<br />
<br />
if ( !WaitNamedPipe(lpczPipeName, 20000) ) <br />
{ <br />
printf("Could not open pipe"); <br />
return FALSE;<br />
} <br />
} <br />
<br />
DWORD dwBytesWritten = 0; <br />
DWORD dwBytesWrite = m_strMsgText.GetLength();<br />
DWORD dwRet;<br />
<br />
OVERLAPPED WriteOverLap = {0};<br />
WriteOverLap.hEvent = CreateEvent(<br />
NULL,
TRUE,
FALSE,
NULL);
<br />
HANDLE hEvent;<br />
hEvent = WriteOverLap.hEvent;<br />
if( !WriteFile(hPipe, m_strMsgText, dwBytesWrite + 1, &dwBytesWritten, &WriteOverLap) )<br />
{<br />
if (GetLastError() == ERROR_IO_PENDING)<br />
{<br />
dwRet = WaitForSingleObject(WriteOverLap.hEvent, 10000);<br />
if (dwRet != WAIT_OBJECT_0)
{<br />
CloseHandle(WriteOverLap.hEvent);<br />
CloseHandle(hPipe);<br />
hPipe = NULL;<br />
return FALSE;<br />
}<br />
}<br />
else <br />
{<br />
CloseHandle(WriteOverLap.hEvent); <br />
CloseHandle(hPipe);<br />
hPipe = NULL;<br />
return FALSE;<br />
}<br />
}<br />
<br />
CloseHandle(WriteOverLap.hEvent); <br />
CloseHandle(hPipe);<br />
hPipe = NULL;<br />
<br />
return TRUE; <br />
}<br />
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Have you tried putting a breakpoint (or several) in the thread proc and watching what is
happening?
The debugger is your friend!
Mark
Mark Salsbery
Microsoft MVP - Visual C++
"Great job team! Head back to base for debriefing and cocktails."
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hi mark,
yup I already did that ...
the funny thing is that the spawned thread is terminating when I run it with breakpoints
and when I put messageboxes.
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After OnInitDialog()of Dialog-based applications, how the dialog is getting the message from Windows. Is the dialog polling or by wake up?
Best Regards,
Suman
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AFAIK, the application waits until a message is received. So, no CPU time is consumed during this wait (not like if you were actively polling).
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rp_suman wrote: After OnInitDialog()of Dialog-based applications, how the dialog is getting the message from Windows. Is the dialog polling or by wake up?
If it's a modal dialog then DoModal has a message loop for processing messages, and if it's a non modal dialog box then m_pMainWnd of CWinApp class helps in doing that. CWinApp::Run function has a message loop that processes messages on m_pMainWnd and this is the reason my we have to set m_pMainWnd in InitInstance member function of CWinApp derived class.
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Right, so I would like to put a custom control into the status bar in Windows Explorer while my namespace extension is showing, much like you would if you were writing your own MFC/ATL/WTL-based program.
However, all I've managed to find anywhere are articles on how to do it in your own MFC/ATL/WTL-based program or how to use IShellBrowser::SetStatusTextSB.
Is what I want to do possible?
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Hai All,
I'm creating a dialog based application.I want the first dialog that gets created from Inintinstance of App to be a modeless one.My problem is that if i use create() i've to declare the dialog object,with a scope in the entire application(ie, on heap).If I declare it in the demo2.h.I've tried so but getting erors when I'm trying to declare an object of app say myapp.
Please suggest me where I went wrong.Also please tell me is it possible to have the first window in an application to be a modless one.If so pls tell me the way to do that.
Thanks in advance
Robs here
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What is your puropse of doing that? Making the dialog [from a dialog-based app] be modeless is meaningless unless you specify the aim.
Anyway, if you look at the InitInstance method, you will see that this method will not return until CMyDlg::DoModal returns. Note that the application will exit if the InitInstance exits in a dialog based app. So if your dlg were modeless you'd not do much for him as the app would exit just after the dlg displayed.
Still you may simulate smth like what you want. The code in InitInstance might look like so;
CMyDlg *pDlg = new CMyDlg();
pDlg->Create(CMyDlg::IDD, NULL);
// you may use CWnd::GetDesktopWindow() instead of NULL if it make sense
pDlg->ShowWindow(SW_SHOW);
CWinThread::Run();
// Here CWinThread::Run enters a message loop and thus will prevent the app exit instantly.
The only remaining point was to exit the app when the dialog closed. So you should have PostQuitMessage inside CMyDlg::PostNcDestroy;
PostQuitMessage(0);
delete this;
Once again, these all are note a good practice...
--
=====
Arman
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