bstr question - C / C++ / MFC Discussion Boards

Daniel Turini22-Aug-02 10:55

22-Aug-02 10:55

No problems here at all...

I've seen a similar problem with a (unavailable) network path in the LIB environment variable, or in the lib search directories configured in VC.

Concussus surgo.
When struck I rise.

Re: VC++ 6.0 hangs during link on WinXP

txseedhead22-Aug-02 11:11

txseedhead

22-Aug-02 11:11

Daniel:

Thanks for the response.

All of my lib paths (environment var and config'd in vc++) are local and exist.

This problem also happened on another machine in the office (WinXP-Pro). In both cases the problem didn't show up the 1st couple of weeks after the machine was set up, but then slowly got worse.

Re: VC++ 6.0 hangs during link on WinXP

Tomasz Sowinski22-Aug-02 11:15

Tomasz Sowinski

22-Aug-02 11:15

Maybe you should clean temporary files?

Tomasz Sowinski -- http://www.shooltz.com

"Yields falsehood when preceded by its quotation" yields falsehood when preceded by its quotation.

Re: VC++ 6.0 hangs during link on WinXP

Mike Nordell25-Aug-02 3:34

Mike Nordell

25-Aug-02 3:34

Are you running (actually, have you even ever installed - running or not) some anti-virus program? If so, try uninstalling it (just disabling it won't work in many cases).

how to compare _variant_t with "a"

ns22-Aug-02 10:20

22-Aug-02 10:20

This compiled okay when I set

_variant_t abc = "a";

But didnt like it when I tested it like this

if (abc == "a")

also tried

if(!strcmp(abc, "a")

How do I compare a variant? Also, maybe I;m not even allowed to assign it like I did, but it did compile at the assignmentThank you,
ns

Re: how to compare _variant_t with "a"

Daniel Turini22-Aug-02 10:28

Daniel Turini

22-Aug-02 10:28

(_bstr_t)abc == "a"

Concussus surgo.
When struck I rise.

Re: how to compare _variant_t with "a"

Michael Dunn22-Aug-02 10:29

Michael Dunn

22-Aug-02 10:29

Use the _bstr_t conversion method to get the string back.

if ( (_bstr_t) abc == _bstr_t("a") )

--Mike--
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bstr question

ns22-Aug-02 10:04

22-Aug-02 10:04

I have :

_bstr_t bstrFile(L"");

I want to detect later if its empty. How do I do this?

CanI say if(bstrFile == "") DoThis();

Or will it have to be a strcmp or something?

Actually I dont really know why it has to be a bstr. Heres the code thats using it. Perhaps some object in it needs a bstr:

CFileDialog pDialog1(TRUE,"*.bmp", "*.bmp", OFN_HIDEREADONLY ,"Image Files
                             (*.bmp;*.dib;*.gif;*.jpg;*.jpe;*.ico;*.cur)");
pDialog1.m_ofn.lpstrTitle = "Open Sketch";
if(pDialog1.DoModal() == IDOK)
{
    CFile file((LPCTSTR)pDialog1.GetFileName(),CFile::modeRead);
    bstrFile1 = file.GetFilePath();
}

which is then used by:

strmBlob->Type = adTypeBinary;
strmBlob->Open(vtEmpty,adModeUnknown,adOpenStreamUnspecified,bstrEmpty,bstrEmpty);

// load image to the blob field
if(bstrFile strmBlob->LoadFromFile(bstrFile);

so it might be that the _StreamPtr strmBlob (__uuidof(Stream) ); needs to read in a bstr filename....

Thanks,
ns

Re: bstr question

Ernest Laurentin22-Aug-02 10:27

Ernest Laurentin

22-Aug-02 10:27

ns wrote:
I want to detect later if its empty. How do I do this?

use: bstrFile.length() == 0

ÿVOTD: 15 "The eyes of the Lord are on the righteous and his ears are attentive to their cry;
16 the face of the Lord is against those who do evil, to cut off the memory of them from the earth. " - Psalm 34:15-16 (1 Peter 3:11-12) (NIV)

Re: bstr question

Stephane Rodriguez.22-Aug-02 10:48

Stephane Rodriguez.

22-Aug-02 10:48

(from MSDN) virtual CString CFile::GetFilePath( ) const;

It does not return a BSTR ! (at least in MFC7, may be true with MFC6 however).

Other question you ask is how to check if a _bstr_t is empty : you have _bstr_t::length() implemented and ready. Same question with BSTR, you must use the native WIN32 method ::SysStringLen(yourbstr),

And I swallow a small raisin.

Dialog Bars

Chun Te, Ewe22-Aug-02 9:51

Chun Te, Ewe

22-Aug-02 9:51

Dear all,

I would like my dialog bar to be permenantly docked to the left frame. Is there anyway to do this?

Thanks.
CT

Re: Dialog Bars

Ernest Laurentin22-Aug-02 10:16

Ernest Laurentin

22-Aug-02 10:16

Call DockControlBar(pYourBar, AFX_IDW_DOCKBAR_LEFT) from your FrameWnd

No ole object (blob) entered in database

ns22-Aug-02 9:20

22-Aug-02 9:20

I give the user a chance to pick a bmp file with cFileDialog. In the event he cancels out, I want to put some sort of non-null identifying entry into the database field where the blob was supposedto be stored. Now if this were a text field, I'd just put in a "_" if my entry was an empty string. But here, what shal I put into the field (access type Ole Object) That way when I go to read this field, if I see my identfying entry I can exit gracefully without further processing and an appropriate messagebox.. I hope my dilemma is clear to you. Plesae let me know if you have any ideas.
Thanks,
ns

Re: No ole object (blob) entered in database

Tomasz Sowinski22-Aug-02 9:34

Tomasz Sowinski

22-Aug-02 9:34

Can't you just use null (in the relational DB sense)?

Tomasz Sowinski -- http://www.shooltz.com

"Yields falsehood when preceded by its quotation" yields falsehood when preceded by its quotation.

Re: No ole object (blob) entered in database

ns22-Aug-02 9:41

22-Aug-02 9:41

How would I recognize it when i went to read it out? I know my stuff crashes if I have blank entries in my database for text, so I had to resort to "" replaced by "_". The db doesnt quite like me to say
rs->fields("A")->value = NULL (putting in data)

and

if (rs->fields("A")->value == NULL) DoSomething(); getting out data.

Thats also because the db I created in code does not allow zero length entries simply because I didnt find the commnad to make it do so.
ns

Re: No ole object (blob) entered in database

Tomasz Sowinski22-Aug-02 10:01

Tomasz Sowinski

22-Aug-02 10:01

It seems your DB experience is extremely thin Smile | :)

One of major concepts in databases are null values. This has nothing to do with C/C++ NULL pointer. Null value designates something which is unknown/not present. SQL provides special operators, like "IS NULL" or "IS NOT NULL", because you can't compare things with NULL.

Your example with "_" as special string is ideal candidate for using null values, as is the blob situation.

How do you set/check for null values in ADO? I don't know; it's been few years since I've coded last database app, and I was using OLEDB (ADODB underlying technology).

Tomasz Sowinski -- http://www.shooltz.com

"Yields falsehood when preceded by its quotation" yields falsehood when preceded by its quotation.

Distribution problem

Keith Goddard22-Aug-02 9:08

Keith Goddard

22-Aug-02 9:08

I have created a fairly simple "database" program for a friend of mine - it uses an Access database, and ADO to connect the user interface (created with VC++ 6.0) with it. I have deployed this app on a variety of test machines, and it worked perfectly on each one.

However, it does not work on my friend's machine! The app simply does not "connect" with the database - there are no errors, but it doesn't retrieve any data whatsoever. The machine in question is running Windows 98 First Edition, and he doesn't have Access installed (not normally a problem). The Access Drivers installed were version 3.5, so I upgraded them using MDAC 2.1 to ver 4.0. That hasn't solved the problem....

Has anyone else had this hassle? Is it actually the Access driver version cauing the problem, or is it something else? PLEASE help!

Re: Distribution problem

Tomasz Sowinski22-Aug-02 9:25

Tomasz Sowinski

22-Aug-02 9:25

www.microsoft.com/data[^] has the necessary downloads. Look for Jet4 SP3 in 'Downloads' section.

Tomasz Sowinski -- http://www.shooltz.com

"Yields falsehood when preceded by its quotation" yields falsehood when preceded by its quotation.

Trouble passing CTreeCtrl parameter

brianwelsch22-Aug-02 8:57

brianwelsch

22-Aug-02 8:57

I'm trying to send in a CTreeCtrl into a dialog member function from CMainFrame. I get an error back saying:
cannot convert parameter 1 from 'class CTreeCtrl' to 'class CTreeCtrl'
No copy constructor available for class 'CTreeCtrl'

In addition to my dialog class and MainFrm.h, I have the following included:
#include <windows.h>
#include <afxwin.h>
#include <afxcmn.h>

My prototype seems to match the function implementation. Any clues?
Thanks

BW
{insert witty/thought-provoking saying here}

Re: Trouble passing CTreeCtrl parameter

C^hris L^osinger22-Aug-02 9:08

C^hris L^osinger

22-Aug-02 9:08

try passing a pointer or reference to the CTreeCtrl...

void CClass::Whatever(CTreeCtrl &tree)

-c

Though the cough, hough and hiccough so unsought would plough me through,
enough that I o'er life's dark lough my thorough course pursue.
--Stuart Kidd

image effects!

multi-tier architecture

Anonymous22-Aug-02 8:46

Anonymous

22-Aug-02 8:46

multi-tier architecture
hi, newbie in this... everything we code today should be packaged in components - COM (QUESTION 1: did .NET just changed this all? can we just wrap everything up in dll as Windows Service). these COM packages can communicate via:

(a) sockets, u can wrap data in XML...
(b) simple in-process local COM server (dll)
OR
simple out-of-process local COM server (exe)
(c) DCOM

QUESTION 2: now, how can i decide which technology is appropriate? of course, sockets only send "data". it doesnt invoke any service. If u need to invoke something that has NOT been previously initiated, u must resort to COM/DCOM...

thanx!

Font: Exist or not?

BlackSmith22-Aug-02 7:09

BlackSmith

22-Aug-02 7:09

How can I assure if some font exist in the system?
CFont::CreateFont(...,lpszFaceName) always returns TRUE, although the lpszFaceName is fabricated! How can I validate this???
I thought maybe use Find/LoadResource(), but I don't know in which module I find those diiiamn fonts. Mad | :mad:

Help me, while sanity is on my side... Big Grin | :-D

--BlackSmith--

"With the help of all mighty", 2001, Me.

Re: Font: Exist or not?

l a u r e n22-Aug-02 7:17

l a u r e n

22-Aug-02 7:17

The CreateFont function does not create a new Windows GDI font. It merely selects the closest match from the fonts available in the GDI’s pool of physical fonts.

from msdn ... meaning that the non-failure of the CreateFont() function is intended ... a font nearest to what you requested is always made available

if you want a specific font (bad bad bad) then you should make it part of your installer program

Smile | :)

"... and so i said to him ... if it don't dance (or code) and you can't eat it either f**k it or throw it away"
sonork: 100.18128 8028finder.com

Re: Font: Exist or not?

Tomasz Sowinski22-Aug-02 7:29

Tomasz Sowinski

22-Aug-02 7:29

BlackSmith wrote:
How can I validate this???

Check EnumFontFamiliesEx API.

Tomasz Sowinski -- http://www.shooltz.com

"Yields falsehood when preceded by its quotation" yields falsehood when preceded by its quotation.

Default CSP and GetLastError() (Encryption Problems)

esapp42022-Aug-02 6:11

esapp420

22-Aug-02 6:11

Hello,
I posted on this yesterday, but I am still having trouble.
I am using this code:

<br />
// Get handle to the default provider. <br />
if(!CryptAcquireContext(&hCryptProv, NULL, MS_DEF_PROV, PROV_RSA_FULL, 0))<br />
{<br />
     HandleError("Error during CryptAcquireContext.");<br />
     return -4;<br />
}

to aquire a handle to the Default CSP. Handle error goes like this:

<br />
void CFPCommonFunctions::HandleError(CString strFunction) <br />
{ <br />
     CString strMsg;<br />
     strMsg.Format("CFPCommonFunctions::EncryptTransFile() - %s: %u.", strFunction, GetLastError());<br />
     AfxMessageBox(strMsg, MB_OK | MB_ICONEXCLAMATION);<br />
}

which returns the error 80090019 (I dont think this is formatted correctly by my function because I cant find this error in the Windows list)

I have no problems on my Win2000 machine, nor do I have a problem on my Win98 machine that has VS6 installed.

My beta users are getting this error every time, and when I try it on a fresh Win95 OSR2 install I get the error as well.

MSDN says this is compatible with Win95 OSR2 and later.

Can anybody see where I am going wrong???

Thanks

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