C / C++ / MFC

Re: CRecordSet->MoveFirst() exception

18-Jul-04 7:15

Is the new record being added successfully? Have you checked the database for that? Sometimes you get an exception because you are doing something illegal but it will not appear right away.

// Afterall, I realized that even my comment lines have bugs

If the sun were to blow up, it would take us 7-8 minutes to realize it.

Scozturk18-Jul-04 7:23

Scozturk

18-Jul-04 7:23

Use this to find out what the exception is really about:

<br />
try<br />
{<br />
	pSet->AddNew...<br />
        pSet->Move....<br />
}	<br />
catch(_com_error &e)<br />
{<br />
_bstr_t bstrSource(e.Source());<br />
_bstr_t bs =  _bstr_t(" Error: ") + _bstr_t(e.Error()) + _bstr_t("Message: ") <br />
+ _bstr_t(e.ErrorMessage()) + _bstr_t("\nDescription:\n") <br />
+ _bstr_t(e.Description());        <br />
MessageBox(0,bs,bstrSource, MB_OK);<br />
}<br />

I hope this helps!

Well... I am a beginner ...

Re: CRecordSet->MoveFirst() exception

Alexander Wiseman18-Jul-04 9:05

18-Jul-04 9:05

Hi,

You also might want to check how you're opening the recordset. The recordset must not be opened as forwardOnly, otherwise it will be a read-only recordset which can only move in one direction, so it would not support calls like MoveFirst().

The other problem might be that, if your recordset is previously empty, and then you call AddNew() but fail to call Update(), then your recordset will still be empty and MoveFirst() will fail. MSDN states that you must call Update() after calling AddNew(), otheriwse no changes will be made and no warning will be given. Thus, if your recordset is empty, the exception will be thrown on the MoveFirst() call.

So two things:
1) Make sure the recordset is not opened with type forwardOnly
2) Make sure you are calling CRecordset::Update() AFTER you call AddNew(), otherwise no record will actually be added.

Hope that helps.

Sincerely,
Alexander Wiseman

Est melior esse quam videri
It is better to be than to seem

LOGPEN

Trollslayer18-Jul-04 6:47

Trollslayer

18-Jul-04 6:47

I am trying to write to a bitmap in order to create graduated irregular shapes and this means changing the colour many times.
I am trying to do this with CreatePen but when I try to access properties of the created LOGPEN there is an exception.
Any suggestions ?

Elaine Rose | [Rose]

The tigress is here Big Grin | :-D

Re: LOGPEN

Trollslayer18-Jul-04 8:37

Trollslayer

18-Jul-04 8:37

I got it working - use

<br />
	pen1.CreatePen(PS_SOLID, 3, i*8);  // create the pen i nthe desired colour<br />
	pDC->SelectObject(pen1);           // set the device context to use it<br />
	rect2.left++;			   // bring in width on each side<br />
	rect2.right--;<br />
	pDC->Ellipse(rect2);               // draw shaded elipse<br />
	pen1.DeleteObject();               // delete the pen so you can create next with different colour<br />

The tigress is here Big Grin | :-D

Re: LOGPEN

Alexander Wiseman18-Jul-04 9:06

Re: LOGPEN - resource usage warning

18-Jul-04 9:06

Heh, sorry I didn't see your post because I had the browser open for a while and didn't refresh the page.

Sincerely,
Alexander Wiseman

Est melior esse quam videri
It is better to be than to seem

PJ Arends18-Jul-04 9:06

PJ Arends

18-Jul-04 9:06

You forgot to select the pen out of the device context before calling DeleteObject().

"You're obviously a superstar." - Christian Graus about me - 12 Feb '03

"Obviously ??? You're definitely a superstar!!!" mYkel - 21 Jun '04

Within you lies the power for good - Use it!

Re: LOGPEN

Alexander Wiseman18-Jul-04 8:56

Get a pointer from an RVA

18-Jul-04 8:56

Hello,

Are you using the CPen class, or simply the Win32 GDI function CreatePen?

If you are using the CPen class, you get a LOGPEN like this:

<br />
CPen myPen;<br />
myPen.CreatePen(PS_SOLID, 1, RGB(255,0,0));<br />
<br />
//Get LOGPEN:<br />
LOGPEN myLogPen;<br />
myPen.GetLogPen(&myLogPen);<br />

If you then wanted to change the color of the pen, you could change the LOGPEN property, delete the CPen object and then use FromHandle or CreatePen, passing the LOGPEN back to the object.

If you are using the Win32 GDI function, I think it returns an HPEN, in which case I'm not very clear about what your question is.

I realize the stuff I said in here is pretty basic and that you probably have a more complicated question, so maybe I just misunderstood it. In any case, if you can explain a little more I'll see if I can help you.

Sincerely,
Alexander Wiseman

Est melior esse quam videri
It is better to be than to seem

Toni7818-Jul-04 6:43

Re: Get a pointer from an RVA

18-Jul-04 6:43

template <class T> LPVOID GetPtrFromRVA( DWORD rva, T* pNTHeader, PBYTE imageBase ) // 'T' = PIMAGE_NT_HEADERS 
{
	PIMAGE_SECTION_HEADER pSectionHdr;
	INT delta;
		
	pSectionHdr = GetEnclosingSectionHeader( rva, pNTHeader );
	if ( !pSectionHdr )
		return 0;

	delta = (INT)(pSectionHdr->VirtualAddress-pSectionHdr->PointerToRawData);
	return (PVOID) ( imageBase + rva - delta );
}

These lines of code were taken from Matt Pietrek's PEDump (http://www.wheaty.net/[^]). This function takes an RVA and gives you an actual memory address where this RVA is located.
imageBase - is the image base where the PE file being viewed is mapped.
pSectionHdr - is a pointer to a section where the rva falls in.
Now I don't understand the last line of the function. Wouldn't imageBase + rva be enough? Why would we factor in this delta variable? On top of that, pSectionHdr->VirtualAddress and pSectionHdr->PointerToRawData point at the same information but in two different contexts. The VirtualAddress is the RVA of the section and PointerToRawData is the file offset of the section. Therefore, the load offset cannot always be the same as the file offset.

// Afterall, I realized that even my comment lines have bugs

If the sun were to blow up, it would take us 7-8 minutes to realize it.

bikram singh19-Jul-04 12:55

bikram singh

19-Jul-04 12:55

gah?!

Bikram Singh

Problem Creating a server on the local PC using CAsyncSocket

femi ashiru18-Jul-04 6:42

femi ashiru

18-Jul-04 6:42

Hi, i am developing a mini server using the CAsyncSocket class to allow communication between a Macromedia flash based front-end application and a VC++ back-end on the same PC.

I assumed the server should run on port 80, however i was not sure whether i should use 'localhost' for the server name or create a new one. I used the ffg code sequence to start the server however it fails on the specifed port.

// Create the server
m_csLocalServer = "";
m_nLocalPort = 80;
BServerStatus = GetPeerName(m_csLocalServer,m_nLocalPort);
m_BServerStatus = MainServer.Create(m_nLocalPort,SOCK_STREAM,FD_READ | FD_WRITE | FD_OOB | FD_ACCEPT | FD_CONNECT | FD_CLOSE,m_csLocalServer);

if(m_BServerStatus != 0)
{
m_csServerResponse = "The server has been started";
}

I'll appreciate if anyone can tell me what im doing wrong

cheers,

femi.

Re: Problem Creating a server on the local PC using CAsyncSocket

valikac18-Jul-04 13:59

valikac

18-Jul-04 13:59

So class MainServer is derived from CAsyncSocket?

Kuphryn

Directory Date/Time

Atlence18-Jul-04 4:04

Atlence

18-Jul-04 4:04

Hi!

I'm looking for a way to change a directory creation date.

I tried SetFileTime API function, it works well for files, but doesn't work for directories...

How to change the creation date of a directory?

Thks in advance!
Appstmd
http://www.atlence.com

Toni7818-Jul-04 7:32

18-Jul-04 7:32

HANDLE hDir = CreateFile(
			".\\testFolder",                            // pointer to the file name
			FILE_LIST_DIRECTORY|FILE_WRITE_ATTRIBUTES,                // access (read/write) mode
			FILE_SHARE_READ|FILE_SHARE_DELETE,  // share mode
			NULL,                               // security descriptor
			OPEN_EXISTING,                      // how to create
			FILE_FLAG_BACKUP_SEMANTICS,         // file attributes
			NULL                                // file with attributes to copy
			);

	if( hDir == INVALID_HANDLE_VALUE )
	{
		printf( "Cannot open directory!\n" );
		return 0;
	} // end if

	FILETIME CreationTime;
	if( !GetFileTime( hDir, &CreationTime, NULL, NULL ) )
	{
		printf( "Couldn't read file time\n");
		return 0;
	} // end if

	CreationTime.dwLowDateTime ^= 0x0101010101010101;
	CreationTime.dwHighDateTime ^= 0x0101010101010101;

	if( !SetFileTime( hDir, &CreationTime, NULL, NULL) )
	{
		printf( "Couldn't set file time\n");
		return 0;
	} // end if

	CloseHandle( hDir )

// These two lines are there just so that the time will change drastically
// and that the changes would be visible to your eye. So you need to remove
// them in your application
CreationTime.dwLowDateTime ^= 0x0101010101010101;
CreationTime.dwHighDateTime ^= 0x0101010101010101;

Instead of GetFileTime, you can use GetSystemTime or whatever you wish to do.

// Afterall, I realized that even my comment lines have bugs

If the sun were to blow up, it would take us 7-8 minutes to realize it.

Atlence18-Jul-04 14:19

Atlence

18-Jul-04 14:19

Thks you for your answer. It works very well now!

Thks in advance!
Appstmd
http://www.atlence.com

Atlence2-Apr-05 12:55

Atlence

2-Apr-05 12:55

Hi!

I have tested your code under Windows 98. It seems that the flag FILE_FLAG_BACKUP_SEMANTICS is not supported under this system.

Is there another way to change the date of a directory under Windows 95/98?

Thks in advance!
Appstmd
http://www.atlence.com

Toni7829-Apr-05 13:30

29-Apr-05 13:30

I am sorry Atlence. I haven't done any coding for months now. I have gotten rusty. I checked the SDK and this is what it states:

Directories

An application cannot create a directory with CreateFile; it must call CreateDirectory or CreateDirectoryEx to create a directory. Opening a directory with CreateFile requires the FILE_FLAG_BACKUP_SEMANTICS flag.

FILE_FLAG_BACKUP_SEMANTICS Indicates that the file is being opened or created for a backup or restore operation. The system ensures that the calling process overrides file security checks, provided it has the SE_BACKUP_NAME and SE_RESTORE_NAME privileges. For more information, see Changing Privileges in a Token. 
You can also set this flag to obtain a handle to a directory. Where indicated, a directory handle can be passed to some functions in place of a file handle. 

Windows Me/98/95:  This flag is not supported.

A few years back I could do it directly with assembly code but nowdays Windows XP won't allow direct access to anything anymore.

// Afterall, I realized that even my comment lines have bugs

If the sun were to blow up, it would take us 7-8 minutes to realize it.

Toni789-May-05 6:42

9-May-05 6:42

Atlence,

It just hit me that a few years back when I was more involved with assembly I would use DOS interrupts to change the time of the files. You could use those techniques in Windows 98. I believe that Windows 98 allows you direct access to the hardware (I could be wrong on this). Run a search on DOS interrupts and functions.

If you want this to work on both XP and Windows 98 then make sure that you do something like this:

if( Windows XP )
use FILE_FLAG_BACKUP_SEMANTICS
if (Windows 98 )
use DOS interrupts

It might not be the best solution but it will work. Sorry for the late reply but as I said earlier I haven't done much programming late.

// Afterall, I realized that even my comment lines have bugs

If the sun were to blow up, it would take us 7-8 minutes to realize it.

Dialog Problem

Kunal Shetye18-Jul-04 2:44

Kunal Shetye

18-Jul-04 2:44

My project consists of 3 dialogs outof which 2 have been
inserted using Insert->New Form method in VC++ 6.0

The problem is that i dont know how to initialise the new
dialogs and display them when the user clicks a button

Eg: Dlg = DialogBox, BT = Button

Dlg1 consists on 2 buttons BT1,BT2
If user clicks BT1 then Dlg2 should be shown
Elseif user clicks BT2 then Dlg3 should be shown

Can anyone please give the code required for the above procedure?

Thankyou for reading

$TELOPHASE$

Re: Dialog Problem

Alexander Wiseman18-Jul-04 3:22