Re: Please help!! - COM Discussion Boards

Stephane Rodriguez.7-Aug-03 23:34

7-Aug-03 23:34

adsilva wrote:
I get error at code GetDiskFreeSpaceEx as "cannot convert parameter 1 from char[4] to const unsigned short* "

static TCHAR HardDiskLetters[][MAX_OF_HARD_DISKS]={
"c:\\", "d:\\", "e:\\", "f:\\", "g:\\", "h:\\",
"i:\\", "j:\\", "k:\\", "l:\\", "m:\\", "n:\\",
"o:\\", "p:\\", "q:\\", "r:\\", "s:\\", "t:\\",
"u:\\", "v:\\", "w:\\", "x:\\", "y:\\", "z:\\"
};

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adsilva7-Aug-03 23:56

7-Aug-03 23:56

Thanks a lot!!

But now I am getting 25 errors after changing char to TCHAR. Do I need to add any header file to get rid of the errors.
The error is as follows
error C2440: 'initializing' : cannot convert from 'char [4]' to 'unsigned short'
This conversion requires a reinterpret_cast, a C-style cast or function-style cast

Thanks

Anna

Stephane Rodriguez.8-Aug-03 0:00

8-Aug-03 0:00

I didn't only change char to TCHAR. I have also changed the order in [][] dimensions.
The overall code compiles and runs fine on my machine (vc++6.0).

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adsilva8-Aug-03 0:08

8-Aug-03 0:08

Sorry!! Still I just can't get rid of the errors!!

D:\Backup Codes\Crypts\Serialno.cpp(18) : error C2440: 'initializing' : cannot convert from 'char [4]' to 'unsigned short'
This conversion requires a reinterpret_cast, a C-style cast or function-style cast

Note: I have used this code in ATL COM .

Thanks ,

Anna. Frown | :(

Stephane Rodriguez.8-Aug-03 0:35

8-Aug-03 0:35

adsilva wrote:
D:\Backup Codes\Crypts\Serialno.cpp(18) : error C2440: 'initializing' : cannot convert from 'char [4]' to 'unsigned short'

There's something odd anyway. The error should be "cannot convert from 'char [4]' to 'unsigned short*" (note the *) since GetDiskDriveSpaceEx takes a LPCTSTR as first parameter. LPCTSTR is unsigned short* if you compile with UNICODE, and is unsigned char* if not.

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adsilva8-Aug-03 0:52

8-Aug-03 0:52

Earlier I was getting the following error when I was declaring harddiskletters as
static char HardDiskLetters[MAX_OF_HARD_DISKS][4]={
"c:\\", "d:\\", "e:\\", "f:\\", "g:\\", "h:\\",
"i:\\", "j:\\", "k:\\", "l:\\", "m:\\", "n:\\",
"o:\\", "p:\\", "q:\\", "r:\\", "s:\\", "t:\\",
"u:\\", "v:\\", "w:\\", "x:\\", "y:\\", "z:\\"
};

D:\Backup Codes\Crypts\Serialno.cpp(52) : error C2664: 'GetVolumeInformationW' : cannot convert parameter 1 from 'char [4]' to 'const unsigned short *'
Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast

After changing to
static TCHAR HardDiskLetters[][MAX_OF_HARD_DISKS]={
"c:\\", "d:\\", "e:\\", "f:\\", "g:\\", "h:\\",
"i:\\", "j:\\", "k:\\", "l:\\", "m:\\", "n:\\",
"o:\\", "p:\\", "q:\\", "r:\\", "s:\\", "t:\\",
"u:\\", "v:\\", "w:\\", "x:\\", "y:\\", "z:\\"
};

I am getting 25 errors which points to the line where the above declaration is made.
the error reads as follows

D:\Backup Codes\Crypts\Serialno.cpp(18) : error C2440: 'initializing' : cannot convert from 'char [4]' to 'unsigned short'
This conversion requires a reinterpret_cast, a C-style cast or function-style cast

Thanks,

Anna.

Stephane Rodriguez.8-Aug-03 1:16

8-Aug-03 1:16

If you rollback to what you had before you could explicitely cast

HardDiskLetters[i]

to :

(LPCTSTR)(HardDiskLetters[i])

I believe the compiler would be ok then. Quite honestly, I didn't suggest this solution first because explicit cast at this point is bad code.
If you are willing to keep the code I suggest, just send it to me so I can test it (make a zip, and forward it by clicking on the [Email] link below).

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adsilva8-Aug-03 1:45

8-Aug-03 1:45

Thanks a lot!! Smile | :)

Its working now . I explicitly type casted HARDDISKLETTERS as you mentioned.

I have a query. I want to assign a varaible declared as DWORD to a string .
For eg;
DWORD harddiskspace ;
I get some value in harddiskspace . I want to retrieve as a string .

Thanks ,
Anna.

Stephane Rodriguez.8-Aug-03 2:07

8-Aug-03 2:07

#include <stdio.h>

char szTmp[32];
DWORD harddiskspace = ...;
sprintf(szTmp,"%ld",harddiskspace);

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Internet Explorer custom menu

Mike_V9-Aug-03 11:55

Mike_V

9-Aug-03 11:55

Don't do it that way! What you need to do is:

<br />
#define MAX_OF_HARD_DISKS 24<br />
static TCHAR HardDiskLetters[MAX_OF_HARD_DISKS][4]={<br />
_T("c:\\"), _T("d:\\"), _T("e:\\"), _T("f:\\"), _T("g:\\"), _T("h:\\"),<br />
_T("i:\\"), _T("j:\\"), _T("k:\\"), _T("l:\\"), _T("m:\\"), _T("n:\\"),<br />
_T("o:\\"), _T("p:\\"), _T("q:\\"), _T("r:\\"), _T("s:\\"), _T("t:\\"),<br />
_T("u:\\"), _T("v:\\"), _T("w:\\"), _T("x:\\"), _T("y:\\"), _T("z:\\")<br />
};<br />

This will compile as either an ANSI array of strings or a UNICODE array of strings. By casting, you would be passing an 8-bit string to a function that expects a 16-bit string. The function could not work with that. Also, note the order of the array subscripts. This should work - but I did not test it.

Good Luck,
Mike_V

Mohsen Saad7-Aug-03 18:55

Mohsen Saad

7-Aug-03 18:55

How can I add a custom menu to Internet Explorer(i.e an extra menu to Internet Explorer like utilities to do certain task)

for people with experience with ActiveX Controls..

safee ullah7-Aug-03 1:49

safee ullah

7-Aug-03 1:49

hi there..

firstly thanks for your time..

secondly i wanted to know 3 things:
1. my container also crashes when i remove my control from the test container...cant figure out the reason...possibly something to do with the releasing of this pointer..

2. what is the normal procedure in which u can exit a control, i mean all the releases and exitinstances and destructors?

3. from where can i get a sample OLE control so that i can use it for studying purposes..

thanks and kindest regards
safee

Re: for people with experience with ActiveX Controls..

Stephane Rodriguez.7-Aug-03 6:09

Re: for people with experience with ActiveX Controls..

7-Aug-03 6:09

The simplest way to solve the issue is to start a debug session for your ActiveX component by first of all pointing the executable to "ActiveX test container" in your Project settings \ Debug Tab.
If you put a breakpoint in a destructor somehow, the session will halt there and hopefully it will be possible to isolate the issue.

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safee ullah7-Aug-03 23:16

safee ullah

7-Aug-03 23:16

yup got it..
thanks a lot Smile | :)

One more thing if u may have time..how can i check for memory leaks in my application??

ne ideaz!

thanks
kindest regards
safee

Re: for people with experience with ActiveX Controls..

Stephane Rodriguez.7-Aug-03 23:25

Re: for people with experience with ActiveX Controls..

7-Aug-03 23:25

safeeullah wrote:
One more thing if u may have time..how can i check for memory leaks in my application??

When the debug session ends, it shows all leaks in the console window. If you are using MFC, you'll have plenty of details and will be able to double-click on the messages to reach the actual code being guilty. If you are not using MFC, you can instrumentalize your code by either of those :
- lookup this article[^] on CodeProject
- buy a commercial product like BoundsChecker (from Numega).

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safee ullah8-Aug-03 0:17

safee ullah

8-Aug-03 0:17

thanks stephane..
one last thing Smile | :)

i solved the crashing issue as well as the leak checking..
then i build my control in release mode..

when i built it in release mode, my spreadsheet stopped taking in data entries to cells..

ne information on this?

thanks again Wink | ;)

Re: for people with experience with ActiveX Controls..

Stephane Rodriguez.8-Aug-03 0:30

calling vc6 dll from vb6 activex dll

8-Aug-03 0:30

safeeullah wrote:
when i built it in release mode, my spreadsheet stopped taking in data entries to cells..

1) Check out you don't have significant code in a

#ifdef _DEBUG
...
#endif

section. Because in release mode, no code would be generated.

2) If the debug mode works fine, and the release mode doesn't, it's usually because the code is weak. There is a probably a bad use of pointers somewhere.

- check out the console window for all "exception errors" that might be produced by Excel (or any other ActiveX host).
- build the release mode with "Debug Info". And check the ".pdb" box. Doing so, you can put a breakpoint even in release mode.
- Add a DebugBreak() statement in your code. This allows to halt the code, start a session, and watch variables, etc. To have this to work properly, it's best to generate a release version with all the debug info (see above).
- add a few message boxes in your code, and watch them. That's the most primitive way of solving issues, but sometimes it's enough!

Good luck!

And if you are to go on with debugging, crash handlers, etc. don't hesitate to buy this book[^].

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patwilliams6-Aug-03 5:53

patwilliams

6-Aug-03 5:53

After reading several boards, I'm close but no cigar. I have an existing C++ app that calls my vc6 dll which calls a vb6 dll. That seems to work fine except when I try to call a function in the vc dll from the vb dll. It works fine if I call the c++ dll from a vb exe. For this test, the calling vc app does a simple call to fakePlugIn().

The vc dll:

#include "stdafx.h"
#import "testvb.dll"
using namespace testvb;

extern "C" __declspec(dllexport) fakePlugIn()
{
HRESULT hresult;
CLSID clsid;
_vbdllcls *t;

CoInitialize(NULL); //initialize COM library
hresult=CLSIDFromProgID(OLESTR("testvb.vbdllcls"), &clsid);
hresult=CoCreateInstance(clsid,NULL,CLSCTX_INPROC_SERVER,__uuidof(_vbdllcls),(LPVOID *) &t);
if(FAILED(hresult))
{
AfxMessageBox("Creation Failed");
return false;
}
t->InVbDll("string to vb dll"); //call the vb dll
t->Release();
CoUninitialize();
return true;
}

extern "C" void __declspec(dllexport) Callback(void)
{
AfxMessageBox("in callback");
}

The vb code:

Public Declare Function Callback Lib "testcpp.dll" () 'this is in a module

Public Function InVbDll(ByVal s As String) As Long 'this is in class vbdllcls
MsgBox s
Callback
End Function

With Callback defined as __declspec(dllexport), the message box in Callback gets executed but then I get a runtime error: Run-Time Check Failure #0 - The value of ESP was not properly saved across a function call.

OK so I tried __stdcall instead. Then I don't make it to the Callback and get a runtime error:

First-chance exception at 0x77e73887 in cppshell.exe: 0xC000008F: Floating-point inexact result.
First-chance exception at 0x77e73887 in cppshell.exe: Microsoft C++ exception: _com_error @ 0x0012fbac.

I've tried various combinations as well with the same result. Ultimately, I'd like to pass strings into and possibly out of Callback, but one step at a time.

Any light you could shed on this would be appreciated!

Using MS Web Browser ActiveX Control

Douglas Troy5-Aug-03 5:11

Douglas Troy

5-Aug-03 5:11

I am hosting the Web Browser control in an application, and am setting the initial nav URL to a local directory. I would like to default the "View" to Thumbnails, but I cannot find where the View Type property is exposed.

Does anyone know how I can get access to this property and set it?

I have checked all the exposed interfaces for this control and did not see where this might be exposed as a method. The IWebBrowser2 interface exposes two Methods "GetProperty and PutProperty", not sure I could use these, mainly because I would have to know the property to get/put.

Any help would be great!

Thanx,

D.

Stephane Rodriguez.6-Aug-03 10:53

6-Aug-03 10:53

Douglas Troy wrote:
I am hosting the Web Browser control in an application, and am setting the initial nav URL to a local directory. I would like to default the "View" to Thumbnails, but I cannot find where the View Type property is exposed.

There is no relationship, or at least I am not aware of it, between the web browser control which can be used to navigate web pages, and the windows explorer thumbnail view.
More to the point, where the web browser is used is for image preview when windows explorer is in web page mode (not in thumbnail view) : in this mode, windows explorer reads and executes the html code described in <windows dir> \ folder.htt. By default this code uses an ActiveX control to build a picture preview from the current file selection.

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Douglas Troy7-Aug-03 5:57

Douglas Troy

7-Aug-03 5:57

If your application hosts the Web Browser control and you point your initial nav location to a local drive, it will display a list of files (like standard Windows Explorer) ... I was hoping that I could somehow drill down into the shell to hook the view type and set it by default to Thumbnail.

I'll mess with the Folder.htt, and see if perhaps we can't just dump that file into our images directory and get it to automatically thumb that folder.

Thanks,

D.

Stephane Rodriguez.7-Aug-03 6:07

7-Aug-03 6:07

HRESULT IShellView::CreateViewWindow(
IShellView *psvPrevious,
FOLDERSETTINGS *pfs,
IShellBrowser *psb,
RECT *prcView,
HWND *phWnd
);

where

typedef struct {
UINT ViewMode;
UINT fFlags;
} FOLDERSETTINGS, *LPFOLDERSETTINGS;

and ViewMode is :

typedef enum {
FVM_FIRST = 1,
FVM_ICON = 1,
FVM_SMALLICON = 2,
FVM_LIST = 3,
FVM_DETAILS = 4,
FVM_THUMBNAIL = 5,
FVM_TILE = 6,
FVM_THUMBSTRIP = 7,
FVM_LAST = 7
} FOLDERVIEWMODE;

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QueryInterface -- How come this code doesn't work?

Douglas Troy7-Aug-03 7:03

Douglas Troy

7-Aug-03 7:03

Excellent! I must be blind, because I swear I checked my Platform SDK Docs IShellView and did not see reference to the File Folder struct you've provided here; I'll check again.

Thank you for the information, this is a big help,

D.

Popeye Doyle Murray5-Aug-03 4:16

Popeye Doyle Murray

5-Aug-03 4:16

Here is the code:

// this line gets a valid ADO database connection object
_ConnectionPtr pConnection = m_AdoDatabase.GetActiveConnection();


// Now I will get a pUknown pointing to the database connection
IUnknown* pUnk;

// this is successful
HRESULT hr = pConnection->QueryInterface(IID_IDispatch, (void**) &pUnk);


// Now I will attempt to get an ADO connection object from pUnknown
_ConnectionPtr pConnection2;

// this line fails
hr = pConnection->QueryInterface(__uuidof(Connection), (void**) &pConnection2);

if (FAILED(hr))
{
 // this is where the failure is!
 // hr is returned with a value E_NOINTERFACE
  TRACE("Failed to get pointer the second time.\n");
  TRACE("Error:  %s\n\n", GetComError(hr));
}

Shouldn't I be able to go from an ADO Connection object, to IUnknown, and then back again? How do I get back my ADO Connection from IUnkown?

Re: QueryInterface -- How come this code doesn't work?

Stephane Rodriguez.5-Aug-03 5:49