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I am of the opinion that you cannot just do that with normal member functions, and expect everything to work correctly, due to the absence of a suitable this pointer. You can use a static member function quite easily, however.
While it is possible to cheat and call a member function directly, there likely not be a valid this pointer when one is to be expected, so if the function tried to access any member variables, or call a virtual function, things would likely break.
However, it looks like you are trying to map a symbol to the return value of a function call (like the simple homework assignment of creating a calculator), so you can map the function name (the string) to a pointer-to-a-common-base-class from which you can call methods off of.
Peace!
-=- James.
"Fat people are hard to kidnap."
(Try Check Favorites Sometime!)
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Your function must be static or global.
Use a static callback, it's more elegant!
typedef double (CALLBACK* MemberFunctionPointer)(double dVal);
and define your function like this:
double CALLBACK CYourClass::ASpecialFunction(double dVal)
{
return DoSomething( dVal );
}
By the way, why would you like to have pi function? Is this
a school project? 
"One good thing about getting older, you don't loose the ages you've been!"
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With the pointer to member, you explicitly pass an object to the invokation of the function pointer call, so there is in fact a this pointer available. No cheating! In my example, the object happens to be the one invoking the function, but this isn't necessarily the case. Here's how I used it:
RESULT r = ((*this).*pFunc)(dValue);
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No, it must be an actual non-static member function. The state of the object is important to the calculation.
The pi function was just to demonstrate the idea. In practice, the calculations are less trivial.
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Perhaps you can find tricks from the implementation of CRuntimeClass
which have CreateObject() and m_pfnCreateObject .
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To All,
Thanks for your help and advice. I got this working the way I intended, and everything works fine.
Aaron
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CTreeCtrl uses SetItemData() to associate a pointer to an object. In my tree ctrl every object stands for a string. Is there any way to associate a string with an item using SetItemData() without creating a new string and pointer to it then adding passing that through SetItemData()?
hope that makes some sort of sence 
basicly i have a loop which adds all of my items and i want it to call SetItemData() after adding it, and associate the item just added with a string
thanks for any insight!
-dz
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You can store pointers to strigns (or whatever thing, for that matter), but it is your responsibility to keep track of the lifespan of these objects: in other words, these objects must be stored somewhere else, as what you're passing to the CTreeCtrl are just pointers.
If you're familiar with lists and strings, this pseudocode shows the general idea:
class CMyDlg
{
...
std:list<std::string> m_item_strings;
void populate_tree()
{
for(...){
HITEM hItem=m_tree.InsertItem(...);
std::string item_string=...;
m_item_strings.push_back(item_string);
m_tree.SetItemData(hItem,(DWORD)&m_item_strings.back());
}
}
};
Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo
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i m using winsock control in MFC application.its Connect method is
Connect(const VARIANT& RemoteHost, const VARIANT& RemotePort).
i dont now how to pass these parameters.infact i dont know much about VARIANTS.plz send me piece of code to use this fuction.
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This is not a funny a answer but use CAsyncSocket class or CSocket. Those are very easy to use!
Sorry to disappoint ya!
Rickard Andersson@Suza Computing
ICQ#: 50302279 (Add me!)
E-mail: nikado@pc.nu
I'm from the winter country SWEDEN!
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This is good coding:
// Prototype
LRESULT CALLBACK SubClassProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
.
.
.
LRESULT CALLBACK SubClassProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
return DefWindowProc(hWnd, uMsg, wParam, lParam);
}
.
.
.
// Somewhere in the code...
wpOldProc = (WNDPROC)SetWindowLongPtr(this->hControl, GWL_WNDPROC, (LONG)SubClassProc);
.
.
.
Why isn't this good coding???
class SomeClass
{
.
.
.
LRESULT CALLBACK SubClassProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
.
.
.
};
.
.
.
LRESULT CALLBACK SomeClass::SubClassProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
return DefWindowProc(hWnd, uMsg, wParam, lParam);
}
.
.
.
//Further in some function:
wpOldProc = (WNDPROC)SetWindowLongPtr(this->hControl, GWL_WNDPROC, (LONG)SubClassProc);
.
.
.
I contantly get a type cast error. WHY???
I really want to work object oriented, so please give an object oriented example of this.
LPCSTR Dutch = "Double Dutch "
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This problem is explained in some detail in Mike Dunn's C++ FAQ.
Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo
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Hi, everyone
I am developing a Windows Application using Visual C++ 6.0. This application is going to be called by another program. When that program calls my windows application, it will pass several parameters to my win application. Could anyone tell me how to make my windows application take parameters?
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The "LPSTR lpCmdLine" parameter in the WinMain function holds the parameters.
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could you please tell me how should I do this? I am not very familiar with VC++?
thanks.
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try searching in the articles or in MSDN there should be some examples.
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In your WinMain function, the third parameter is a LPTSTR (char*) called lpstrCmdLine. This is where your command line parameters will come in. You can simply process the string data in this field just line you would for the argv parameters of the main function for a console application.
If you want to run your program in the debugger and send command line parameters to your app, you can go to the menu Project | Settings, then select the debug tab, and set the program arguments field.
If you are using MFC (which is a little different) or you need more help just ask.
Good Luck.
Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!
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I am a little confused, kilowatt.
What I would like to do is:
when the external program calls my win application, it passes (let's assume) 1 parameter, which is a string. Then in my win application, I would like to display this parameter. How could I implement this? Could you possible specify it in details? I am using Visual C++ 6.0.
Thanks a lot.
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you could store this string, for example:
char str[32];
WinMain(...)
{
strcpy(str, lpCmdLine);
}
and in some function display it in a messagebox like this:
MessageBox(hWnd, str, "", MB_OK);
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where can i find the winmain() function?
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For MFC applications, use CWinApp::lpCmdLine. Example:
<br />
CString str;<br />
str = AfxGetApp()->lpCmdLine;<br />
MessageBox(str);<br />
Above code will popup a message box which displays whatever parameter you passed to your application exe.
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what about multiple parameters? how can I separate them? one character by one character?
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No matter how many parameters you have entered, that's always a command "line", for example, if your app exe named "abc.exe" and you typed the following line to launch your program:
<br />
abc.exe -s -a -p -nodemo -window<br />
that line consists of 5 parameters, the contents of lpCmdLine will be:
<br />
"-s -a -p -nodemo -window"<br />
It's YOUR responsiblity to parse the command line into individual parameters, and that's pretty easy if you ask me. By the way, you will need to tell the users how to specify command line parameters when you ship your application, thus you should know the rule of parsing.
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When i use this function, the path to each subfolder doesen't get added to the listview, what gets added is the path to the desktop folder and then the subfolder name of the folder the user selected in the SHBrowseForFOlder dialog, for example: C:\Documents and Settings\Administrator\Dekstop\<subfolder name>
here's the code:
void OnOpenFolder()
{
BROWSEINFO bi = {0};
IShellFolder *pSf;
LPMALLOC pMalloc;
LPENUMIDLIST pFolder = NULL;
DWORD pActual = 0;
LVITEM Lvi = {0};
char szFolderPath[MAX_PATH+1];
bi.hwndOwner = ghWnd;
bi.pidlRoot = NULL;
bi.lpszTitle = "Locate MP3 Folder";
bi.ulFlags = BIF_DONTGOBELOWDOMAIN;
bi.lpfn = NULL;
SHGetDesktopFolder (&pSf);
if (pSf)
{
LPITEMIDLIST pIdl;
pIdl = SHBrowseForFolder(&bi);
SHGetPathFromIDList(pIdl, szFolderPath);
Lvi.mask = LVIF_TEXT;
Lvi.pszText = szFolderPath;
Lvi.iItem = SendMessage(DlgItems[7], LVM_GETITEMCOUNT, 0, 0);
ListView_InsertItem(DlgItems[7], &Lvi);
if (pIdl)
{
IShellFolder *pBrowse = NULL;
SHGetMalloc(&pMalloc);
pSf->BindToObject(pIdl, NULL, IID_IEnumIDList, (LPVOID*)&pBrowse);
pSf->Release();
pBrowse->EnumObjects(NULL, SHCONTF_FOLDERS | SHCONTF_NONFOLDERS | SHCONTF_INCLUDEHIDDEN, &pFolder);
if (pBrowse)
{
while (pFolder->Next(1, &pIdl, &pActual) == S_OK)
{
SHGetPathFromIDList(pIdl, szFolderPath);
Lvi.pszText = szFolderPath;
Lvi.iItem = SendMessage(DlgItems[7], LVM_GETITEMCOUNT, 0, 0);
ListView_InsertItem(DlgItems[7], &Lvi);
}
}
pBrowse->Release();
}
pMalloc->Free(pIdl);
pMalloc->Release();
}
pSf->Release();
}
Anyone know what's wrong?
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I just dug up some old code that was calling SHBrowseForFolder and I noticed that I used:
BIF_RETURNONLYFSDIRS | BIF_STATUSTEXT
for the bi.ulFlags member. Try that and see if it makes a difference.
Regards,
Alvaro
Insanity: doing the same thing over and over again and expecting different results. - Albert Einstein
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