C / C++ / MFC

Re: Dynamic array of afx_msg functions - using CPtrArray ( MFC VC 6.0)

2-Jan-12 15:56

I am looking for a way to have a dynamic ( run time) array of afx_msg functions.
I have tried this with some success.
CPtrArray pArray;
pArray.Add((void*) OnFunctionkeysCallsate());
pArray.Add((void*) OnWindowNewlogview());
int iTest = pArray.GetSize();
iTest = pArray.GetUpperBound();
void * pElement = pArray.GetAt(0);
void * pElement_1 = pArray.GetAt(1);
Here are my problems
1. The GetSize returns 2 but GetAt(0) and GetAt (1) return same pointer. Why?
2. The Add method adds the function to the pointer array just fine but also runs it. I can live with that but like to know why it does that.
3. I have no clue what GetAt actually returns and how to use it.
4. I realize this approach still does not provide for dynamic add of a function. Working on that – I guess passing function as variable documentation should help.
5. Is it really “legal” to change the afx_msg function from void to void * as I did?
Thanks for your help. It is really appreciated.
Have a great 2012.
Vaclav

Chuck O'Toole2-Jan-12 16:01

Chuck O'Toole

2-Jan-12 16:01

pArray.Add((void*) OnFunctionkeysCallsate());

Calls the OnFunctionkeysCallsate() function and stores the result of that call into pArray. If I understand you correctly, this is not what you want. Instead, you want the address of the function, not the result of invoking the function. Remove the "()".

Re: Dynamic array of afx_msg functions - using CPtrArray ( MFC VC 6.0)

Vaclav_2-Jan-12 16:39

Re: Dynamic array of afx_msg functions - using CPtrArray ( MFC VC 6.0)

2-Jan-12 16:39

Thanks, pretty stupid mistake on my part as far as caling the function.
Now I need to really figure out how to pass the function as void pointer. Or maybe I need to change the CPtrArray?
I'll work on that.

-- modified 2-Jan-12 22:54pm.

ThatsAlok3-Jan-12 19:45

ThatsAlok

3-Jan-12 19:45

Chuck O'Toole wrote:
pArray.Add((void*) OnFunctionkeysCallsate());

partially agree, however i believe you missed & before function name at time of addition to ptrarray collection

"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
Support CRY- Child Relief and You

Re: Dynamic array of afx_msg functions - using CPtrArray ( MFC VC 6.0)

Chuck O'Toole3-Jan-12 21:38

Chuck O'Toole

3-Jan-12 21:38

Sorry, I don't see any '&' in the original post and it does not appear to be edited. Which '&' are you talking about?

Re: Dynamic array of afx_msg functions - using CPtrArray ( MFC VC 6.0)

ThatsAlok3-Jan-12 23:12

ThatsAlok

3-Jan-12 23:12

Chuck O'Toole wrote:
Sorry, I don't see any '&' in the original post and it does not appear to be edited. Which '&' are you talking about?

Actually I meant to say, you need to store the address of function to the CPtrArray, if you try to compile as you mentioned in your post, you will see compiler error as mentioned by actual poster in same thread!

cheers,
Alok Gupta
VC Forum Q&A :- I/IV
Support CRY- Child Relief and You

Re: Dynamic array of afx_msg functions - using CPtrArray ( MFC VC 6.0)

Vaclav_3-Jan-12 4:55

Re: Dynamic array of afx_msg functions - using CPtrArray ( MFC VC 6.0)

3-Jan-12 4:55

OK gurus, I need some serious help here. I am over my head with this one, really.

How do I pass afx_msg function to the CPtrArray?
I understand that CPtrArray wants void* pointer, but the compiler still complains and I really do not understand the error codes.
Here is the code and the compiler errors. The first afx_msg function still retruns void*, just FYI, if it makes any difference now.

Thanks for your help.

pArray.Add((void*) (OnFunctionkeysCallsate));
pArray.Add((void) (OnWindowNewlogview));
MainFrm.cpp
E:\0 OpenLog\V1\TCC\MainFrm.cpp(683) : error C2440: 'type cast' : cannot convert from 'void *(__thiscall CMainFrame::*)(void)' to 'void *'
There is no context in which this conversion is possible
E:\0 OpenLog\V1\TCC\MainFrm.cpp(684) : error C2664: 'Add' : cannot convert parameter 1 from 'void' to 'void *'
Expressions of type void cannot be converted to other types
Error executing cl.exe.

ThatsAlok3-Jan-12 19:43

ThatsAlok

3-Jan-12 19:43

if your customer allow you to use stl and function OnFunctionkeysCallsate and OnWindowNewlogview have same signature, you can use this piece of code to achieve same:-

C++

void Function1(int i)
{
    cout<<"Hello in Function 1 Number " <<i;
}


void function2(int i)
{
    cout<<"Hello in Function 2 Number " <<i;
}
typedef void (*MySingleArgFunction) (int);

///Main Function
vector<MySingleArgFunction> vecFuncPtr;
	vector<MySingleArgFunction>::iterator it;
	vecFuncPtr.push_back(&Function1);
	vecFuncPtr.push_back(&function2);


	it=vecFuncPtr.begin();

	while(it!=vecFuncPtr.end())
	{
		(*it)(20);
		it++;
	}

and if still insist on CPtrArray, so here is the pointer to solve above problem :-

you missed a & in

Vaclav_Sal wrote:
pArray.Add((void*) (OnFunctionkeysCallsate));
pArray.Add((void) (OnWindowNewlogview));

which should be written as

pArray.Add((void*) &OnFunctionkeysCallsate);

cheers,
Alok Gupta
VC Forum Q&A :- I/IV
Support CRY- Child Relief and You

Re: Dynamic array of afx_msg functions - using CPtrArray ( MFC VC 6.0)

Vaclav_4-Jan-12 7:16

Re: Dynamic array of afx_msg functions - using CPtrArray ( MFC VC 6.0)

4-Jan-12 7:16

Thanks for your reply.
I have already tried adding &. The compiler does not like it.

pArray.Add((void*)&OnFunctionkeysCallsate);

And here is the error message

E:\0 OpenLog\V1\TCC\MainFrm.cpp(683) : error C2276: '&' : illegal operation on bound member function expression

I'll take a look at the vector method.
I am also looking at MFC CMenu.
Vaclav

ThatsAlok5-Jan-12 2:44

ThatsAlok

5-Jan-12 2:44

Vaclav_Sal wrote:
have already tried adding &. The compiler does not like it.

pArray.Add((void*)&OnFunctionkeysCallsate);

And here is the error message

ahh i understand, i believe OnFunctionkeysCallsate is the function defined in the class, if yes then you have to put the code like this:-

pArray.Add((void*)&YouClassNameWhereFunctionISDefines::OnFunctionkeysCallsate);

cheers,
Alok Gupta
VC Forum Q&A :- I/IV
Support CRY- Child Relief and You

Re: Dynamic array of afx_msg functions - using CPtrArray ( MFC VC 6.0)

Vaclav_5-Jan-12 6:08

class array, better understanding of it

5-Jan-12 6:08

Sorry, still no go
Here is the compiler error message:

MainFrm.cpp
E:\0 OpenLog\V1\TCC\MainFrm.cpp(685) : error C2589: '&' : illegal token on right side of '::'
E:\0 OpenLog\V1\TCC\MainFrm.cpp(685) : error C2059: syntax error : '::'

It seems that this should work. BTW it is all in MainFrm.cpp
pArray.Add((void*)CMainFrame::&OnFunctionkeysCallsate);

Unless you are just curious why it does not, you can just drop it. I am still looking at the CMenu , maybe that will work.

I basically need an array of function pointers I can execute in desired sequence.
Thanks for all your help.
Vaclav

jkirkerx2-Jan-12 13:14

2-Jan-12 13:14

I'm working on a class array, but I thought it would structure my data different.

I'm working with this code below. I was hoping it would create a single object, with 2 internal members of [0] and [1] creating a single object uaListBoxPtrArray with 2 members [0] Tim and [1] John, Tim and John being inside uaListBoxPtrArray.

But it looks like it creates separate objects
uaListBoxPtrArray[0] which is Tim
uaListBoxPtrArray[1] which is John
and I would have to pass uaListBoxPtrArray[0], uaListBoxPtrArray[1] to a function.

I want to be able to pass the single object to a function in the future, and not separate objects. pass uaListBoxPtrArray by itself, with Time and John inside it.

Q: Is my result or implementation correct?, and that this is the correct result format for the method below?. Or do I now need to work on the constructor, to form a single object of records.

CSS

DWORD dwCount;
DB_UserAccount dbUA;
dwCount = dbUA._get_UserAccount_Listbox_Count();

// Create an Class Array Structure to hold the values
UA_Listbox **uaListBoxPtrArray;
uaListBoxPtrArray = new UA_Listbox*[dwCount];

uaListBoxPtrArray[0] = new UA_Listbox;
uaListBoxPtrArray[0]->iUserID = 47;
uaListBoxPtrArray[0]->szFirstName = L"Tim";
uaListBoxPtrArray[0]->szLastName = L"Parker";
uaListBoxPtrArray[0]->szAccountName = L"tparker";

uaListBoxPtrArray[1] = new UA_Listbox;
uaListBoxPtrArray[1]->iUserID = 48;
uaListBoxPtrArray[1]->szFirstName = L"Joe";
uaListBoxPtrArray[1]->szLastName = L"Smoe";
uaListBoxPtrArray[1]->szAccountName = L"jsmoe";

Richard MacCutchan2-Jan-12 22:02

2-Jan-12 22:02

jkirkerx wrote:
I was hoping it would create a single object

But the lines:

C++

uaListBoxPtrArray = new UA_Listbox*[dwCount];
uaListBoxPtrArray[0] = new UA_Listbox;
...
uaListBoxPtrArray[1] = new UA_Listbox;

specifically say: create an array of object pointers and create two new objects which can be referenced by the pointers in the array. If you want a single object to hold both names then you need a different class definition.

Unrequited desire is character building. OriginalGriff
I'm sitting here giving you a standing ovation - Len Goodman

jkirkerx3-Jan-12 7:22

3-Jan-12 7:22

Thanks Richard

I just want to make sure that I understood your thoughts correctly first.

Richard MacCutchan wrote:
create an array of object pointers

uaListBoxPtrArray = new UA_Listbox*[dwCount];

Richard MacCutchan wrote:
create two new objects which can be referenced by the pointers in the array

uaListBoxPtrArray[0] = new UA_Listbox;
uaListBoxPtrArray[1] = new UA_Listbox;

Richard MacCutchan3-Jan-12 22:28

3-Jan-12 22:28

That's correct, if you break things down to their constituent parts you get:

C++

UA_Listbox             // declares a UA_Listbox
UA_Listbox*            // declares a pointer to a UA_Listbox
UA_Listbox*[dwCount]   // declares an array of pointers, of length dwCount
uaListBoxPtrArray      // declares an array a variable

So the statement

C++

uaListBoxPtrArray = new UA_Listbox*[dwCount];

initialises an array variable by creating the array of pointers (via the new operator). Each array element can then be initialised with a pointer to an object of the type previously defined.

Unrequited desire is character building. OriginalGriff
I'm sitting here giving you a standing ovation - Len Goodman

jkirkerx4-Jan-12 6:54

4-Jan-12 6:54

Thanks again Richard.

Well my class array worked. I was able to pass the array to the function and get the values back. But after implementing it, changing the design and format several times, I determined that it will never work in the way I wanted it to.

After studying how they work in principle, the source which is a ODBC function creates pointers to buffers in the heap, in which the SQL Handle maintains, and once the handle is freed, the pointers are lost.

So I brought the GUI (hWnd) to the ODBC, populated the listbox, and exited.

No one wonder I was confused, but overall in the end, I learned alot about pointers. Oh Well.

Stefan_Lang3-Jan-12 5:26

Stefan_Lang

3-Jan-12 5:26

Why not this way?

C++

// Create an Class Array Structure to hold the values
UA_Listbox *uaListBoxArray;
uaListBoxArray = new UA_Listbox[dwCount];
 
uaListBoxArray[0].iUserID = 47;
uaListBoxArray[0].szFirstName = L"Tim";
uaListBoxArray[0].szLastName = L"Parker";
uaListBoxArray[0].szAccountName = L"tparker";
 
uaListBoxArray[1].iUserID = 48;
uaListBoxArray[1].szFirstName = L"Joe";
uaListBoxArray[1].szLastName = L"Smoe";
uaListBoxArray[1].szAccountName = L"jsmoe";

// ... do something

delete [] uaListBoxArray; // clean up

jkirkerx3-Jan-12 7:24

3-Jan-12 7:24

That's a question to a question, in which I cannot answer at the moment.

Stefan_Lang3-Jan-12 22:41

Stefan_Lang

3-Jan-12 22:41

You asked how to define a single object containing two UA_ListBox objects and I gave you a definition: Rather than define an array of two pointers, I defined an array of two UA_ListBox objects. If that is not what you want, then sorry, I don't understand the question. (Besides, even your own definition of an array of two pointers to objects in a way satisfies your request: it is a single object representing two objects. Why is this not sufficient for your purposes?)

jkirkerx4-Jan-12 7:08

4-Jan-12 7:08

I can comment on it now, it was a fine post.

I implemented your revised edition, and liked it better, because I wasn't using the new statement for each record.

It worked great, thank you very much.

I ended up deleting the whole thing, and took the gui (hwnd)to the ODBC function. The ODBC function created pointers to buffers, that were held by the SQLHandle. The first array record was fine, but records after that were corrupted.

So I have to rethink how this would work in ODBC, Which is another subject. I'm thinking that I need to implement your version of the array inside the ODBC Function itself.

The code below was a bad idea. I tried using the array directly in the GetData, but I wasn't able to use the size in the array elements. Anyways, that's a different subject.

if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS) {			
												
INT			i = 0;
INT			pzUserID; <- This should of been an array element
WCHAR			pzFirstName[cbFirstName]; <- This should of been an array element
WCHAR			pzLastName[cbLastName]; <- This should of been an array element
WCHAR			pzUserName[cbUserName]; <- This should of been an array element
						
while (SQLFetch(hstmt) == SQL_SUCCESS) {
	// Get Data from the Table
	SQLGetData(hstmt, 1, SQL_C_ULONG, &pzUserID, 0, NULL );
	SQLGetData(hstmt, 2, SQL_C_WCHAR, &pzFirstName, cbFirstName, NULL );
	SQLGetData(hstmt, 3, SQL_C_WCHAR, &pzLastName, cbLastName, NULL );
	SQLGetData(hstmt, 4, SQL_C_WCHAR, &pzUserName, cbUserName, NULL );

        // Original -I used the pointers above to populate the array at this point, but I should of just went direct into the array, instead of using the temporary pointers in between. But in theory once I free the SQL handle, the pointers are gone. So Perhaps in the future, I need to create multi part functions, one that Initializes, one that gets the data and packages it, and one that closes the handle, passing the handle to each function until complete.

}

CreateThread

columbos149272-Jan-12 5:14

columbos14927

2-Jan-12 5:14

Hello,
Im writing an MFC App,
I want to create some threads using the CreateThread function.

The function that i send as a parameter to the createThread function must be declared as static and then i cant reference none static members of my object,how can i by pass it?

Thanks

Re: CreateThread

Richard MacCutchan2-Jan-12 6:18

image processing toolkits | batch image processing

2-Jan-12 6:18

You can still pass an object reference to a static function.

Unrequited desire is character building. OriginalGriff
I'm sitting here giving you a standing ovation - Len Goodman

Re: CreateThread

C^hris L^osinger2-Jan-12 6:56

C^hris L^osinger

2-Jan-12 6:56

something like this:

C++

int CMyClass::staticFunc(void *p)
{
  CMyClass *pObj = (CMyClass *)p;

  ...

  return 0;
}


void CMyClass::someFunc()
{
   CreateThread(NULL, 0, staticFunc, (void *)this, ... );
}

Re: CreateThread

Richard MacCutchan2-Jan-12 7:31