Activex control - COM Discussion Boards

How to use ActiveX control in VC++.Net version.

sheshidar21-Jul-06 18:37

21-Jul-06 18:37

Hi all,
I know how to get Active controls on control tool box in VC++ 6.0. But now i want to use them in .net version(Select Project | Add To Project | Components and Controls from the Visual C++
menu.), but I couldn'd a way to add them . Can any one of you help me in this .
Thanking you.

Sheshi

interview question on COM

pathakr21-Jul-06 3:51

pathakr

21-Jul-06 3:51

Dear Gurus,

You may not be aware that I have lost my job as our company has given us lay off.

I am really expecting a job in MFC, VC++.

I have given 2-3 technical interviews but it has made clear that interviews need special attention and preparation ,

I would be highly thankful , if someone provides me the compilation of interview questions on VC++, MFC, C++, ATL COM, Threading. If with answers then it will be a faster preparation for me. (Sorry being lazy here, but situation is a bit tedious with me right now).

ANy links also will help a lot.

If you want to send me few things, then email address is

rpathak03011978@yahoo.com

Looking forward some help from Codeproject.

Thanks ,

pathak

Re: interview question on COM

sheshidar21-Jul-06 18:58

sheshidar

21-Jul-06 18:58

Hi ..
if u r preparing for interview than first u have to be very good in basic concepts of C++.
Like whats the difference between polymorphism and inheritance.
What is Virtual function.
Why we dont have virtual constructors, and why we have virtual destructors.

and Reg VC++ , MFC..
what is Doc/View arch.
diff. between common DLL's abd MFC DLL's
what is SDK.
what is Inline function.
Message Maps--??
Tell about WindProc()
basic properties of controls(edit, button..)
(ex. whats the diff between check box and radio button)
diff between Modal() and Modaless()..
how u retrieve text in a edit box without using member variables.
..
these r some questions which I faced in Interviews..
but better go through some FAQ's..
all the best..

Sheshidar

DCOM Connection in Windows XP SP2

shibu george21-Jul-06 1:48

shibu george

21-Jul-06 1:48

I encountered one access denied problem with the DCOM in Windows XP Sp2.

I have two COM servers. One say, X is service and another say, Y is an EXE.
I wrote one client application say, Client for Invoke X.

The Client will invoke the Service X (which are running in the same machine).It work successfuly.

The Service X will invoke the COM EXE,which is running in another machine.It will not work.

shibu george

Re: DCOM Connection in Windows XP SP2

sudeesh24-Jul-06 21:01

sudeesh

24-Jul-06 21:01

check the firewall settings.

hello

Re: DCOM Connection in Windows XP SP2

shibu george26-Jul-06 18:51

shibu george

26-Jul-06 18:51

Hi,
I have disabled the Firewall. Set the define the DCOM Remote Access and Remote Launch permissions.But the issue is still the same.

Thanks
Shibu George

Shibu George

Re: DCOM Connection in Windows XP SP2

Steve S26-Jul-06 21:24

Steve S

26-Jul-06 21:24

What do you get in the event log on either machine when it fails?
(and you did remember to register any proxy/stub DLL's, didn't you...)

Activex control

sunita ramesh21-Jul-06 0:24

sunita ramesh

21-Jul-06 0:24

Hello all,

I have an Activex Control in vc++ 6.0.It is a player plays cam files.

I have designed in the way that everytime the Activex control opens ,cam file will be downloaded from the server(Download Dialog) and after downloading the download dialog is closed automatically using OnThreadFinished.

LRESULT CHttpDownloadDlg::OnThreadFinished(WPARAM wParam, LPARAM /*lParam*/)
{
m_bSafeToClose = TRUE;
m_ctrlAnimate.Stop();

if (m_bAbort)
EndDialog(IDCANCEL);
else if (wParam)
{
AfxMessageBox(m_sError);
EndDialog(IDCANCEL);
}
else
EndDialog(IDOK);

return 0L;
}

OnThreadFinished is for closing the dialog after the cam file downloads
fully.

1.Is ther any method to close the dialog while downloading the file.

Help me please and give me ur suggestions.

thanks in advance

Sunita

#pragma pack

anu_8820-Jul-06 23:01

anu_88

20-Jul-06 23:01

hi ,
what is the meaning of #pragma pack ?
From MSDN I came to know that it specifies the packing alignment for structure and union members .

But what is meant by packing alignment ?
Can you please tell me.

Thanks in advance

Re: #pragma pack

Steve S20-Jul-06 23:32

Steve S

20-Jul-06 23:32

If you declare a struct with

char dummy;
short x;
long y;

members, the "optimal" size would be 1 + 2 + 4 (assume x86 for the moment).
However, this would be with alignment of 1. This says what byte boundary you use for packing. With an alignment of 2, each member begins on the next available 2 byte boundary, so the single char would be followed by an unnamed pad byte, the short would already be aligned correctly, as would the long.

Similarly with 4 byte, the char is followed by 3 unnamed pad bytes, the short by another two, and the long would be OK as is.

I can almost hear you asking "Why would I want to waste memory like that?"
[fx: pause for reader to actually ask...]

It's all to do with the way the processor accesses memory, and for some CPUs, like the SPARC, trying to access a packed (1) long would cause an exception.

The important thing is to consistently use the same alignment for all in memory versions of a structure. For instance, if you build a DLL with a function that takes a structure, the declaration of that structure should really include

#pragma pack(push)
#pragma pack(n)
struct {
....
};
#pragma pack(pop)

so that irrespective of the compile time options elsewhere, it has the packing n (where n is a power of 2). Without this, you might build the DLL with pack(2), for instance, and a client might be built with pack(1). This would misalign the data, and might even result in an access violation when you call the DLL function.

Does that help?

Steve S
Developer for hire

Re: #pragma pack

anu_8821-Jul-06 0:32

anu_88

21-Jul-06 0:32

Thank you very much for your reply

safearray of user defined structure store in variant

rudo3220-Jul-06 21:31

rudo32

20-Jul-06 21:31

Hi.
I'm developing MFC Activex library, which deals with data from MS Access DB. I need to make function like
short GetTagStruct(short nTag, VARIANT *arrayTagStruct) - .odl file in vc6++
I want to call this interface function in VB.
Structure can be for example:

<br />
Public Type TagStruct<br />
    sTagName As String<br />
    x As Single<br />
    y As Single<br />
    sObjName As String<br />
    sDispPath As String<br />
    sDispName As String<br />
End Type<br />

I know how to handle BSTR array in Variant, but I don't know what type I should select for safearray of user defined structure. For BSTR it is VT_ARRAY | VT_BSTR.
Can you give me example of using safearray of user defined structure stored variant ?
Thanx.

rudo

Re: safearray of user defined structure store in variant

Aamir Butt25-Jul-06 0:29

Aamir Butt

25-Jul-06 0:29

The Variant type used for this VT_ARRAY | VT_UI1 means a SafeArray of Unsigned Bytes. Which further means that this is simple binary data which you are storing in a variant.

"Some people believe football is a matter of life and death.
I'm very disappointed with that attitude.
I can assure you it is much, much more important than that. -- Bill Shankly"

Re: safearray of user defined structure store in variant

Tim Paaschen25-Jul-06 2:42

Tim Paaschen

25-Jul-06 2:42

Hi,

You can use VT_RECORD, if you define your structure as a UDT (user defined data type). See the MSDN for details on this topic.

Regards,
Tim

Ecxel.dll is not working

ersinsivaz20-Jul-06 10:00

ersinsivaz

20-Jul-06 10:00

I can't write using Excel=Microsoft.Office.Interop.Excel namespace my .NET editor. What can I do for this problem. I am using Office 2003 and I added Microsoft.Excel 11 Object Library and Microsoft Office 11 Object Librry.
For your answers tnahk you ....

This is my sign

safearray access returns junk pls help

nikhil_ag198520-Jul-06 2:07

nikhil_ag1985

20-Jul-06 2:07

Hi All,
Im writing a dll in ATL COM called by a vb.net client. the client passes a 2d integer array when it calls MyMethod.
i have tow problems
I. i have trouble accessing the values in the array passed, i get junk values. this is the code.

<br />
STDMETHODIMP ExposedATLClass::MyMethod(SAFEARRAY **psa)<br />
{<br />
	AFX_MANAGE_STATE(AfxGetStaticModuleState())<br />
	long arrlengthx,arrlengthy;<br />
	long **myarray;<br />
	int indexx,indexy;<br />
	try<br />
	{<br />
		arrlengthx=(*psa)->rgsabound[0].cElements;<br />
		arrlengthy=(*psa)->rgsabound[1].cElements;<br />
		myarray=(long**)malloc(arrlengthx*sizeof(long**));	<br />
                for(long tempvar=0;tempvar<=arrlengthx;tempvar++)<br />
		{<br />
			myarray[tempvar]=(long*)malloc(arrlengthy*sizeof(long*));<br />
		}<br />
		SafeArrayAccessData(*psa,(void**)myarray);	//accessing data stored in safearray by obtaining pointer<br />
		char details[100];<br />
		for(int tempx=0; tempx<=arrlengthx; tempx++, indexx++, indexy=0)<br />
	{<br />
			for(double tempy=0; tempy<=arrlengthy; tempy++, indexy++)<br />
			{<br />
					sprintf(details,"%d %d %d",indexx,indexy,myarray[indexx][indexy]);<br />
					this->Error_Logger(details);	//this function prints 'details' in a txt file.<br />
			}<br />
		}<br />
	}<br />
	catch(CException ex)<br />
	{<br />
		char error[300];<br />
		ex.GetErrorMessage(error,300);<br />
		this->Error_Logger(error);<br />
		ex.Delete();<br />
	}<br />
	return S_OK;<br />
}<br />

in the program

SafeArrayAccessData(*psa,(void**)myarray); returns success

other methods i've used to access data are (replace the line "SafeArrayAccessData(*psa,(void**)myarray);" with code below )
1. using SafeArrayGetElement

<br />
long ai[2]={0,0}<br />
for(int temx=0;temx<=arrlengthx;temx++,ai[0]++)<br />
{<br />
	for(int temy=0;temy<=arrlengthy;temy++,ai[1]++)<br />
{<br />
		SafeArrayGetElement(*psa,ai,&myarray[temx][temy]);<br />
	}<br />
}<br />

here SafeArrayGetElement(*psa,ai,&myarray[temx][temy]); returns index out of bounds

2. using safearraylock/unlock

<br />
/*SafeArrayLock(*psa);	<br />
*myarray=(long*) (*psa)->pvData;<br />
SafeArrayUnlock(*psa);*/<br />

both lock and unlock returned success

all methods return this junk value for myarray[indexx][indexy] -842150451
the values of indexx and indexy are correct and so are the boundaries.

II. my other problem.. no exception is logged.

where am i wrong. pls help
Thanks in advance
Nikhil

GUID [modified]

RRRB20-Jul-06 0:09

RRRB

20-Jul-06 0:09

Hi,

I want to Change GUID, Which generated by vc++, First I want to delete that GUID and Than want to set new GUID.
Thanks in Adv.
Regards,
RRRB Cool | :cool:

-- modified at 7:17 Thursday 20th July, 2006

Re: GUID

nikhil_ag198520-Jul-06 2:14

nikhil_ag1985

20-Jul-06 2:14

Hi,
you can use GUIDGEN.exe
this should be present in the visual studio folder.
regards
nikhil

Re: GUID

RRRB20-Jul-06 2:26

RRRB

20-Jul-06 2:26

Thanks ,But First I want to delete the GUID Which is generated by vc++, After that I want to set my own guid for the same.
Looking forward.... Cool | :cool:

Re: GUID [modified]

sudeesh26-Jul-06 3:07

sudeesh

26-Jul-06 3:07

u can use GuidGen tool which ships with visual studio and replace it in the idl file.

-- modified at 9:09 Wednesday 26th July, 2006

Please help. Problem with including .idl file [modified]

Kiran Pinjala19-Jul-06 21:35

Kiran Pinjala

19-Jul-06 21:35

I have a componant and its idl file. I have included its header file in my stdafx.h and added the .c file into my project with addtoproject file. Actually that .c file containd actual definition of all IIDs and CLSIDs. Now its showing error. End file while looking for precompiled header. What to do now. Actually i dont have a clear idea how to use the classes defined in that componant.
Please tell me how to do that.

KIRAN PINJARLA

-- modified at 3:41 Thursday 20th July, 2006

Re: Please help. Problem with including .idl file

Steve S19-Jul-06 21:59

Steve S

19-Jul-06 21:59

I can help you with the first error;
You need to alter your project settings for the .c file so that it specifies "Not using precompiled headers".

If you're using VC6, you can right-click on file in FileView and select settings, you need C++ tab, category 'precompiled headers'. HINT: change it for 'All configurations' or you'll forget later!

Can't tell you how toi use the classes, since I have no idea what component you have. General stuff though :-

Make sure that you call either OleInitialize (or AfxOleInit if it's an MFC app) or CoInitialize/CoInitializeEx, or you won't be able to do anything.

To get an interface to an instance of the component, you need to call

CoCreateInstance( CLSID_xxxxx, NULL, CLSCTX_ALL, IID_zzzzzz, reinterpret_cast<void**>(&ptr));

where you have IMyInterface* ptr;

Check your return codes, and of course, if that works, eventually you'll need to call

ptr->Release();

Enjoy Smile | :)