C / C++ / MFC

28-Mar-08 3:59

We should treat people equal, no special privilege for me. Smile | :)

regards,
George

derived class

George_George27-Mar-08 20:40

27-Mar-08 20:40

Hello everyone,

What does the following statement about derived class mean?

http://www.gotw.ca/gotw/059.htm

--------------------
Unreasonable Statement #1: "Polymorphism doesn't work in C++ because you can't make an arbitrary class usable in place of a Base& without changing it (to derive from Base)."
--------------------

thanks in advance,
George

CPallini28-Mar-08 0:02

28-Mar-08 0:02

It's an unreasonable statement. What more explanations do you need?
Poke tongue | ;-P

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

George_George28-Mar-08 0:16

28-Mar-08 0:16

I do not know what is the "wrong" unreasonable statement. How do you understand it?

regards,
George

CPallini28-Mar-08 0:31

28-Mar-08 0:31

The whole statement is unreasonable, because it pretends to invalidate the C++ polymorphism because of, general classes cannot exploit polymorphism from a given one without modifications (i.e. deriving from).

But I have to admit, it is not crystalline concept (it simply express author's point of view...)
Smile | :)

George_George28-Mar-08 0:55

Re: About ActiveX Controls

28-Mar-08 0:55

Thanks CPallini,

Do you mean modify the derived class to declare it to inherit from some specific base class? In this senses, we can say it "modifies" something, or in other words, if we can not modify like this, we can not use polymorphism?

regards,
George

About ActiveX Controls

savitri27-Mar-08 20:04

savitri

27-Mar-08 20:04

Hi Everyone,
I write one ActiveX controls.but i dont know how to make that activex control in a single file.Like VB we have Option Make an Ocx file in file menu. so in VC++ also do we have any option to make an activeXcontrol like that. Please REPLY ME SOON.
THANKS IN ADVANCE,
savitri.

_AnsHUMAN_ 27-Mar-08 20:10

_AnsHUMAN_

27-Mar-08 20:10

savitri wrote:
I write one ActiveX controls.but i dont know how to make that activex control in a single file.Like VB we have Option Make an Ocx file in file menu. so in VC++ also do we have any option to make an activeXcontrol like that

Did you choose the project option for creating an ActiveX control. If yes, than when you compile your code a .ocx file would be generated as output.

savitri wrote:
Please REPLY ME SOON.

I hope this solution helps you and was posted SOON.

Somethings seem HARD to do, until we know how to do them.
Wink | ;-)

_AnShUmAn_

Re: About ActiveX Controls

Rajesh R Subramanian28-Mar-08 1:56

Users have the same privilege should share same registry in VISTA.

28-Mar-08 1:56

savitri wrote:
Please REPLY ME SOON.

Please hold your breath until I get back to you.

Nobody can give you wiser advice than yourself. - Cicero
.·´¯`·->Rajesh<-·´¯`·.
Codeproject.com: Visual C++ MVP

DCOM security issue

tony_Udz27-Mar-08 17:50

tony_Udz

27-Mar-08 17:50

Hello,

Using below code i am trying to authorize user "Valid\User1" to create COM object of "TestServiceSecurity" from a remote machine.
This code is working fine that is it not throwing any kind of error but still it is not giving autorization to "User1".

Can anybody help me with this?

Thanks in advance.

*************************************************************************************************************************

BOOL bDaclPresent = FALSE;
BOOL bDaclDefaulted = FALSE;
DWORD dwError = 0;
DWORD dwSize = 0;
EXPLICIT_ACCESS ea;
PACL pacl = NULL;
PACL pNewAcl = NULL;
PSECURITY_DESCRIPTOR psd;
SC_HANDLE schManager = NULL;
SC_HANDLE schService = NULL;
SECURITY_DESCRIPTOR sd = {0};
SERVICE_STATUS_PROCESS ssp;
DWORD dwBytesNeeded;
PSID sid;

schManager = OpenSCManager(0, 0, SC_MANAGER_CONNECT);

if (schManager == NULL)
DisplayError(GetLastError(), TEXT("OpenSCManager"));

schService = OpenService(schManager , "TestServiceSecurity",SC_MANAGER_ALL_ACCESS);
if (schService == NULL)
DisplayError(GetLastError(), TEXT("OpenService"));

psd = (PSECURITY_DESCRIPTOR)HeapAlloc(GetProcessHeap(),
HEAP_ZERO_MEMORY, dwSize);

// Get the current security descriptor.
BOOL bResult = QueryServiceObjectSecurity(schService, DACL_SECURITY_INFORMATION, psd, 0, &dwSize);
if (!bResult)
{
if (GetLastError() == ERROR_INSUFFICIENT_BUFFER){
psd = (PSECURITY_DESCRIPTOR)HeapAlloc(GetProcessHeap(),
HEAP_ZERO_MEMORY, dwSize);
if (psd == NULL){
DisplayError(0, TEXT("HeapAlloc"));
// note HeapAlloc does not support GetLastError()
}

bResult = QueryServiceObjectSecurity(schService, DACL_SECURITY_INFORMATION, psd, dwSize, &dwSize);
if(!bResult)
DisplayError(GetLastError(), TEXT("QueryServiceObjectSecurity"));

}
else
DisplayError(GetLastError(), TEXT("QueryServiceObjectSecurity"));
}

// Get the DACL.
bResult = GetSecurityDescriptorDacl(psd, &bDaclPresent, &pacl, &bDaclDefaulted);
if (!bResult)
DisplayError(GetLastError(), TEXT("GetSecurityDescriptorDacl"));

// Build the ACE.
BuildExplicitAccessWithName(&ea, TEXT("Valid\\User1"), COM_RIGHTS_EXECUTE,
SET_ACCESS, NO_INHERITANCE);

dwError = SetEntriesInAcl(1, &ea, pacl, &pNewAcl);

if (dwError != ERROR_SUCCESS)
DisplayError(dwError, TEXT("SetEntriesInAcl"));

//AddAccessAllowedACEToACL(
bool bIsValidACL = IsValidAcl(pacl);

// Initialize a NEW Security Descriptor.
bResult = InitializeSecurityDescriptor(&sd, SECURITY_DESCRIPTOR_REVISION);
if (!bResult)
DisplayError(GetLastError(), TEXT("InitializeSecurityDescriptor"));

// Set the new DACL in the Security Descriptor.
bResult = SetSecurityDescriptorDacl(&sd, TRUE, /*pNewAcl*/NULL, FALSE);
if (!bResult)
DisplayError(GetLastError(), TEXT("SetSecurityDescriptorDacl"));

// Set the new DACL for the service object.
bResult = SetServiceObjectSecurity(schService, DACL_SECURITY_INFORMATION, &sd);
if (!bResult)
DisplayError(GetLastError(), TEXT("SetServiceObjectSecurity"));

// Close the handles.
bResult = CloseServiceHandle(schManager);
if (!bResult)
DisplayError(GetLastError(), TEXT("CloseServiceHandle"));

bResult = CloseServiceHandle(schService);
if (!bResult)
DisplayError(GetLastError(), TEXT("CloseServiceHandle"));

// Free buffers.
LocalFree((HLOCAL)pNewAcl);
HeapFree(GetProcessHeap(), 0, (LPVOID)psd);

void DisplayError(DWORD dwError, LPTSTR pszAPI)
{
LPVOID lpvMessageBuffer;

FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
FORMAT_MESSAGE_FROM_SYSTEM,
NULL, dwError,
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
(LPTSTR)&lpvMessageBuffer, 0, NULL);

//Now display this string.
_tprintf(TEXT("ERROR: API = %s.\n"), pszAPI);
_tprintf(TEXT(" error code = %u.\n"), dwError);
_tprintf(TEXT(" message = %s.\n"),
(LPTSTR)lpvMessageBuffer);

// Free the buffer allocated by the system.
LocalFree(lpvMessageBuffer);

ExitProcess(dwError);
}

*************************************************************************************************************************

vicky0000027-Mar-08 17:48

vicky00000

27-Mar-08 17:48

Hai all,
my application should share same registry entry for diffrent users of same privilage In Vista. Please let me know if you have any idea.

regards
vicky00000

Re: Users have the same privilege should share same registry in VISTA.

Mathias S.29-Mar-08 3:58

Mathias S.

29-Mar-08 3:58

store it under LOCALMACHINE in the registry and add a new usergroup that you put all the users you want to be able to read/write the registry keys it into that usergroup and then set the ACL for that registry entrie so that that group has full access to it.

is there a tool to monitor the io data translation?

kcynic27-Mar-08 17:40

kcynic

27-Mar-08 17:40

hi,is there a tool which can monitor the specified IO data translation?
I need a tool which can monitor the data translation between one program and the CDROM,not only the action but also the data they exchange each other.

thanks

how to change one BYTE in CString

hanlei000000000927-Mar-08 16:49

hanlei0000000009

27-Mar-08 16:49

Hi, all

<br />
CString cstr = "abcd";<br />
<br />
LPTSTR p = cstr.GetBuffer();<br />
<br />
p[2] = 'r';<br />
<br />
// cstr is abcd, but not is abrd<br />
<br />

I want to change 'c' to 'r' in cstr.

How to do?

Re: how to change one BYTE in CString

Naveen27-Mar-08 17:02

Naveen

27-Mar-08 17:02

hanlei0000000009 wrote:
// cstr is abcd, but not is abrd

CString cstr = "abcd";<br />
cstr.SetAt( 2,'r');

hanlei0000000009 wrote:
I want to change 'c' to 'r' in cstr.

But your purpose is to replace the c with r, you can use the Replace function..

CString cstr = "abcd";<br />
cstr.Replace( 'c','r');

nave

[OpenedFileFinder]

modified on Thursday, March 27, 2008 11:37 PM

Re: how to change one BYTE in CString

Mark Salsbery27-Mar-08 17:04

Mark Salsbery

27-Mar-08 17:04

You rarely need to use GetBuffer(). The CString class has most functions you need, including SetAt()...

    CString cstr = _T("abcd");
    cstr.SetAt(2, _T('r'));

If you insist on using GetBuffer(), remember:

"If you use the pointer returned by GetBuffer to change the string contents, you must call ReleaseBuffer ..."

    CString cstr = _T("abcd");
    LPTSTR p = cstr.GetBuffer();
    p[2] = _T('r');
    cstr.ReleaseBuffer();

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

GetBuffer revenge!

CPallini27-Mar-08 22:21

27-Mar-08 22:21

Rajesh R Subramanian27-Mar-08 22:53

27-Mar-08 22:53

Someone said to me that in the next version of MFC, this function would be renamed to GetBufferIReallyKnowWhatImDoing()

Laugh | :laugh:

Nobody can give you wiser advice than yourself. - Cicero
.·´¯`·->Rajesh<-·´¯`·.
Codeproject.com: Visual C++ MVP

CPallini27-Mar-08 23:56

27-Mar-08 23:56

..and they will also add the method PlzGetBuf, always throwing by design.
Smile | :)

ThatsAlok28-Mar-08 0:37

ThatsAlok

28-Mar-08 0:37

CPallini wrote:
..and they will also add the method PlzGetBuf, always throwing by design.

One more GiveMeBufOtherwiseOsama

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow
Never mind - my own stupidity is the source of every "problem" - Mixture

cheers,
Alok Gupta
VC Forum Q&A :- I/IV
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Rajesh R Subramanian28-Mar-08 0:49

28-Mar-08 0:49

CPallini wrote:
PlzGetBuf

Does it take a boolean parameter too? PlzGetBuf(BOOL bUrgent) Roll eyes | :rolleyes:

Nobody can give you wiser advice than yourself. - Cicero
.·´¯`·->Rajesh<-·´¯`·.
Codeproject.com: Visual C++ MVP

CPallini28-Mar-08 0:58

28-Mar-08 0:58

Rajesh R Subramanian wrote:
Does it take a boolean parameter too? PlzGetBuf(BOOL bUrgent)

Actually it does, however it is optional:

PXSTR PlzGetBuf(BOOL bUrgent = TRUE);

Rajesh R Subramanian28-Mar-08 1:02