C / C++ / MFC

Re: Registry error "Invalid handle"

13-May-02 8:58

I have this app where i need to retrieve some settings from the registry, here's my code:

DWORD dwDisposition;
LPCTSTR SubKey = "SOFTWARE\\MP3Reader";
DWORD KeyLen = 0;
HKEY OpenKey;
DWORD DataType = REG_SZ;
DWORD DataLen;
char Data[MAX_PATH+1];


RegCreateKeyEx(HKEY_CURRENT_USER, SubKey, 0, NULL, 0, KEY_READ, NULL, &OpenKey, &dwDisposition);

if (dwDisposition == REG_OPENED_EXISTING_KEY)
{
	RegEnumValue (OpenKey, 0, KeyValue, &KeyLen, NULL, &DataType, (unsigned char *)Data, &DataLen);
	SetDlgItemText (hWnd, IDC_FILEPATH, (LPCTSTR)Data);
}

RegCloseKey (OpenKey);
<pre>

When it comes to the RegCloseKey sentence the following error appears:

Link: http://slimsite.subnet.dk/misc/vcerr.jpg

I don't understand it cause the Registry handle (OpenKey) is used in RegEnumValue and there it works fine cuase it retrieves the value and fills up the Data variable with the correct data, but when it reaches to that specific sentence it doesen't work even though the variable hasn't been manipulated.

Thanks for the help!

Carlos Antollini13-May-02 9:13

Carlos Antollini

13-May-02 9:13

You first must to open the RegKey with RegOpenKeyEx. The last parameter will return you the Handle of the opened key, that you must to use in RegCloseKey Wink | ;)

Bets Regards

Carlos Antollini.
www.wanakostudios.com
Sonork ID 100.10529 cantollini

The RegCreateKeyEx creates or opens a key

redeemer13-May-02 9:25

Re: The RegCreateKeyEx creates or opens a key

13-May-02 9:25

The RegCreateKeyEx function will, if the registry key already exist, open the existing key and return it in the 8th parameter:

LONG RegCreateKeyEx(
  HKEY hKey,                                  // handle to open key
  LPCTSTR lpSubKey,                           // subkey name
  DWORD Reserved,                             // reserved
  LPTSTR lpClass,                             // class string
  DWORD dwOptions,                            // special options
  REGSAM samDesired,                          // desired security access
  LPSECURITY_ATTRIBUTES lpSecurityAttributes, // inheritance
  PHKEY phkResult,                            // key handle 
  LPDWORD lpdwDisposition                     // disposition value buffer
);

And i also tried it before where it worked, i don't know why it doesen't work now...

Bill Wilson13-May-02 11:41

Bill Wilson

13-May-02 11:41

Try checing the error codes on all the calls. Make sure they are returning 0s.

Good Luck,
Bill

Re: Registry error "Invalid handle"

Jason Henderson13-May-02 17:18

Jason Henderson

13-May-02 17:18

Check if RegCreateKeyEx returns ERROR_SUCCESS and close the key only if it is successful.

if (RegCreateKeyEx(...) == ERROR_SUCCESS)
{
// your code here
RegCloseKey(...);
}

Like it or not, I'm right.

simple MFC Q- about inheritance

spoongirl13-May-02 8:26

spoongirl

13-May-02 8:26

is there some mysterious unwritten law against inheriting INDIRECTLY from MFC classes?

i'm having all sorts of trouble trying to do something very simple. here is an example of my woe:

I'd like to create my own Wizard property sheet class, derived from CPropertySheet. ok, well- that's all fine and good, as long as I use the class that inherits directly from CPropertySheet. but try to add another layer, and forget it. will NOT compile.

same thing now happening with CPropertyPage. I'm trying to make a bunch of pages for my wizard, and they share common characteristics. seems like the textbook case of where to use a base class. I'd like to make my base class, WizardPage (or whatever) inherit from CPropertyPage. then all of my actual pages inherit from WizardPage.

no matter what i try, this will not compile. if i try to use one of the child classes, it says "base class undefined" or something. trust me, i included the right headers. Wink | ;)

i would be forever grateful to anyone who can explain why this is happening.

~L

Re: simple MFC Q- about inheritance

Bill Wilson13-May-02 10:01

Bill Wilson

13-May-02 10:01

There is nothing wrong with what you are trying to do. There is no limitation of inheritance from MFC classes or CPropertySheet.

Sorry, but the problem is in your code.

here is a sample:

[ccode]
// Derived.cpp: implementation of the CDerived class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "RegHelper.h"
#include "Derived.h"
#include "MyPropSheet.h"
#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

CDerived::~CDerived()
{

}
CDerived::CDerived(UINT nIDCaption, CWnd* pParentWnd, UINT iSelectPage)
:CMyPropSheet(nIDCaption, pParentWnd, iSelectPage)
{
}

/////////////////////////////////////////////////////////////////////////////
// CMyPropSheet

class CMyPropSheet : public CPropertySheet
{
DECLARE_DYNAMIC(CMyPropSheet)

// Construction
public:
CMyPropSheet(UINT nIDCaption, CWnd* pParentWnd = NULL, UINT iSelectPage = 0);
CMyPropSheet(LPCTSTR pszCaption, CWnd* pParentWnd = NULL, UINT iSelectPage = 0);

// Attributes
public:

// Operations
public:

// Overrides
// ClassWizard generated virtual function overrides
//{{AFX_VIRTUAL(CMyPropSheet)
//}}AFX_VIRTUAL

// Implementation
public:
virtual ~CMyPropSheet();

// Generated message map functions
protected:
//{{AFX_MSG(CMyPropSheet)
// NOTE - the ClassWizard will add and remove member functions here.
//}}AFX_MSG
DECLARE_MESSAGE_MAP()
};

[/ccode]

Hope this helps,
Bill

Re: simple MFC Q- about inheritance

spoongirl14-May-02 5:38

spoongirl

14-May-02 5:38

thanx for the response. i did in fact find the problem not too long after i posted the question.

the main thing i've found is that you have to be really careful about the Class Wizard. it's helpful, but only up to a point. (like, up to the point where you add another level of inheritance to your class heirarchy- eg, if i were to make a class inherit from your CMyPropSheet)

anywyas, thanx again for taking hte time to help out.
Smile | :)

~L (spoongirl)

how to set radio button to be checked?

pnpfriend13-May-02 8:14

pnpfriend

13-May-02 8:14

how to set radio button to be checked?

i want to checked radio button when user go to a menu bar, action menu, and choose menu item named check.

Wes Jones13-May-02 8:25

13-May-02 8:25

Check out:

BOOL CheckDlgButton(
HWND hDlg, // handle to dialog box
int nIDButton, // button identifier
UINT uCheck // check state
);

or

void CWnd::CheckDlgButton( int nIDButton, UINT nCheck );

--------
CheckDlgButton(IDC_MY_RADIO_BTN, BST_CHECKED);

HTH,
-Wes

Sonork ID 100.14017 wtheronjones

Jason Henderson13-May-02 8:44

Jason Henderson

13-May-02 8:44

If you are using a CButton, use SetCheck(1) to check or SetCheck(0) to uncheck.

Like it or not, I'm right.

redeemer13-May-02 9:17

13-May-02 9:17

You can use the BM_SETCHECK message:

SendMessage( 
  (HWND) hWnd,              // handle to destination window 
  BM_SETCHECK,              // message to send
  (WPARAM) wParam;          // check state
  (LPARAM) lParam;          // not used; must be zero
);

Detecting multiple partitions on the same hard drive

Michael Dunn13-May-02 10:26

Michael Dunn

13-May-02 10:26

CheckRadioButton() is the best way - it checks one button and unchecks all others in the group.

--Mike--
Buy me stuff!
Like the Google toolbar? Then check out UltraBar, with more features & customizable search engines!
My really out-of-date homepage
Big fan of Alyson Hannigan and Jamie Salé.
Sonork - 100.10414 AcidHelm

class fstream and dll

Dan Verret13-May-02 8:05

Dan Verret

13-May-02 8:05

I have created a dll in which I use the following linkage interface:

#ifdef CONSOLEDLL_EXPORTS
#define CONSOLEDLL_API __declspec(dllexport)
#else
#define CONSOLEDLL_API __declspec(dllimport)
#endif

every classes have been declared like this:

class CONSOLEDLL_API CCenteredStepEdger : public CStepObject{
friend CONSOLEDLL_API ostream& operator <<( ... );
friend CONSOLEDLL_API istream& operator >>( ... );
...

and some of the classes use fstream type variables:

fstream m_File;

when I compile the project, I have the following warning:

class 'fstream' needs to have dll-interface to be used by clients of class 'CCenteredStepEdger '

How should I specify the dll-interface for the fstream variables???

Thanks

Daniel Verret

Wes Jones13-May-02 7:19

Re: Detecting multiple partitions on the same hard drive

13-May-02 7:19

I'd like to know how I can find out if two drive letters refer to partitions on the same hard drive.

I'm working on a database backup utility, & I want to discourage users from selecting the same physical hard drive for their backups as the hard drive where their 'live database' is running.

ie: If "C:\LiveDatabases" and "D:\My Backups" are actually located on the same physical harddrive(on different partitions), I'd like to know how to determine this info.

Thanks!

Wes

Sonork ID 100.14017 wtheronjones

redeemer13-May-02 9:43

Re: Detecting multiple partitions on the same hard drive

13-May-02 9:43

Try checking out this site: http://www.users.intercom.com/~ranish/part/primer.htm

Wes Jones13-May-02 13:16

Re: Detecting multiple partitions on the same hard drive

13-May-02 13:16

Thanks for the informative link, but I'm looking for API's that I'd be able to use to figure this out.

Thanks!
-Wes

Sonork ID 100.14017 wtheronjones

Jason Henderson13-May-02 17:21

Jason Henderson

13-May-02 17:21

Not sure if this will give you the right info, but check out the GetVolumeInformation function on MSDN and the lpVolumeSerialNumber parameter.

Like it or not, I'm right.

Re: Detecting multiple partitions on the same hard drive

Wes Jones13-May-02 18:03