C / C++ / MFC

Re: Copy a pointer to an element of an array of pointers

6-May-03 4:28

ptr[0] is an actual object, not a pointer to an object. Therefore, it needs to be assigned the value of ptr1, not the address of ptr1.

ptr[0] = *ptr1;

Hans Ruck6-May-03 4:28

Hans Ruck

6-May-03 4:28

The array pointer declaration could be:

ClassA **ptr = new ClassA*[5];

Then use ptr[i] = ClassAPtr.

rechi

Re: Copy a pointer to an element of an array of pointers

jhaga6-May-03 4:36

jhaga

6-May-03 4:36

If you want an array of pointers then do like this
ClassA *ptr[5];
ClassA *ptr1 = somePointerOFClassA;
ClassA *ptr2 = somePointerOFClassA;
and now
ptr[0]=ptr1;

jhaga

Re: Copy a pointer to an element of an array of pointers

Peter Mares6-May-03 4:48

Peter Mares

6-May-03 4:48

the line

ClassA *ptr = new ClassA[5];

defines an array of 5 ClassA objects, not an array of 5 ClassA pointers.

If you want an array of 5 ClassA pointers, your declaration will have to be:

ClassA **ptr = new ClassA*[5];

and then you will be able to execute the following code (or similar):

<br />
ClassA *ptr1 = somePointerOFClassA;<br />
ClassA *ptr2 = somePointerOFClassA;<br />
<br />
ptr[0] = ptr1;<br />
ptr[1] = ptr2;<br />

Now, coming back to your previously mentioned code block.Unfortunately, once you have defined an array as you have :

ClassA *ptr = new ClassA[5];

You cannot actually change the address of an element within that array, ie, you cannot do this:

&ptr[0] = ptr1

Hope this helps some.
Cheers,
Peter

-------------------------------------------
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Fix 1 bug, recompile....
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CoCreateInstance Tracing

Daniel Turini6-May-03 4:01

Daniel Turini

6-May-03 4:01

I have a VB6 (WebClass) application that, from time to time, is failing to create some random COM object (it's not always the same component). From FileMon and RegMon traces I suspect that the error occurs on CoCreateInstance, but I have no access to the HRESULT of CoCreateInstance on VB, so I have no clue of what is the problem.
Does anyone know if is there some application that hooks on CoCreateInstance and allows me to know the HRESULT it is returning?

My latest article: GBVB - Converting VB.NET code to C#

Finding/Loading resources

will13836-May-03 3:37

6-May-03 3:37

Hi all,

I'm trying to find and load a resource from another application. Here's the code I'm using:

HINSTANCE hToDLL;
HRSRC hsrc;
hsrc = FindResource(GetModuleHandle(app),icon,RT_ICON);

where app = "someapp.exe" and
icon = "IDI_ICON3"

This ALWAYS returns a NULL pointer, so it's always failing and the GetLastError always gives me a:

1813 The specified resource type cannot be found in the image file. ERROR_RESOURCE_TYPE_NOT_FOUND

Now I know the resource exists in the application I'm trying to get at, so what am I doing wrong?? Do I need to call LoadLibrary first? I don't think I should have to.

Any insights, help, suggestions, comments are greatly appreciated. Thanks!
Dan

David Crow6-May-03 4:06

6-May-03 4:06

The GetModuleHandle() function retrieves a module handle for the specified module if the file has been mapped into the address space of the calling process. Had you checked the return value of it, rather than immediately calling FindResource(), this might have been evident.

will13836-May-03 4:34

6-May-03 4:34

DavidCrow wrote:
The GetModuleHandle() function retrieves a module handle for the specified module if the file has been mapped into the address space of the calling process. Had you checked the return value of it, rather than immediately calling FindResource(), this might have been evident.

Gotcha,

I understand now, but then what do I need to do to map the file into the address space? Call LoadResource?

Thanks!

Dan

David Crow6-May-03 4:39

6-May-03 4:39

HMODULE hModule;
HRSRC hResource;

hModule = LoadLibrary(...);
if (NULL != hModule)
{
    hResource = FindResource(hModule, ...);
    if (NULL != hResource)
    {
        LoadResource(hResource, ...);
    }

    FreeLibrary(hModule);
}

will13836-May-03 4:44

6-May-03 4:44

Thanks,

I'll try that and report back

basementman6-May-03 4:50

basementman

6-May-03 4:50

Since the module is an EXE, you may want to use the LoadLibraryEx() function instead, passing LOAD_LIBRARY_AS_
DATAFILE for the Flags parameter. This will prevent any calls to unresolved externals (like DllMain) and prevent the loader from loading any dependent dlls that the EXE imports.

will13836-May-03 5:16

6-May-03 5:16

Ok,
I'm further in my understanding, but still no further in a solution. Here's what I have now:

HMODULE hModule;
HRSRC hResource;
sprintf(buff,"%s.exe",app);
hModule = LoadLibraryEx(buff,NULL,LOAD_LIBRARY_AS_DATAFILE);
if (NULL != hModule){
hResource = FindResource(hModule,"IDI_ICON3",RT_ICON);
if (NULL != hResource) {
IUXLogData("the resource exists\n",TRACE1);
//LoadResource(hResource, ...);
} else if ( NULL == hResource ) {
sprintf(buff,
"the %s app is not up to date with error %d\n",
app,
GetLastError());
IUXLogData(buff,IUX_ERROR);
}
FreeLibrary(hModule);
}

I'm still getting an 1814 error though. Still unsure why I am. Is the "IDI_ICON3" or the RT_ICON the wrong stuff? the ICON resource for my test is IDI_ICON3 and I'm sure its in the app I'm trying to open, so I'm confused as to why I'm seeing this.

Any suggestions, insight, comments are greatly appreciated

Thanks!

Dan

basementman6-May-03 5:24

basementman

6-May-03 5:24

You need to wrap the IDI_ICON3 with MakeIntResource as shown in the snippet below:

HRSRC hRscDLL = FindResource(NULL,MAKEINTRESOURCE(IDI_ICON3),RT_ICON);
if (hRscDLL)
{
DWORD dwIconSize = SizeofResource(NULL,hRscDLL);

HGLOBAL hMem = LoadResource(NULL,hRscDLL);
if (hMem)
{
LPVOID pIconBytes = LockResource(hMem);
if (pIconBytes)
{
.........

will13836-May-03 5:36

6-May-03 5:36

Still not having any luck Mad | :mad:

Now i have this:
hResource = FindResource(hModule,MAKEINTRESOURCE(IDI_ICON3),RT_ICON);

but yet it still comes back as NULL Confused | :confused:

Here is how it's defined in the .rc file for the app I'm loading:

// Icon with lowest ID value placed first to ensure application icon
// remains consistent on all systems.
IDI_ICON3 ICON DISCARDABLE "Eye.ico"

So what the heck am I doing wrong?

Any other ideas, suggestions, comments? You're helping alot so far.

thanks!

Dan

David Crow6-May-03 6:02

6-May-03 6:02

Does IDI_ICON3 equate to the same number in both applications?

will13836-May-03 6:47

6-May-03 6:47

DavidCrow wrote:
Does IDI_ICON3 equate to the same number in both applications?

Laugh | :laugh:

good question.

But yes they are the same number. I made sure they were.

The number is 104, and I made sure that the number is the same.

any other ideas Confused | :confused:

Thanks!

Dan

will13836-May-03 7:21