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Hi, all. Below is a program i wrote for test. it contains a class named CBase.
#include <stdio.h>
class CBase{
public:
virtual void VFunction()
{
printf("Hello, VFunction.\n");
}
int _a;
};
int main()
{
CBase obj;
int** ppv;
ppv = (int**)&obj;
void (*pFunc)();
// Now i want pFunc to be assigned to the value of **ppv,
// but it can't be like pFunc = **ppv, right?
return 0;
}
so, what can i do for that? Thanks.
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What are you trying to test? The code doesn't make any sense. Once you do ppv = (int**)&obj;, nothing involving ppv will work right because &obj is not of type int**. The cast forces the assignment to compile, but trying to dereference ppv will cause all sorts of havoc.
--Mike--
http://home.inreach.com/mdunn/
While I can't be correct on all matters, I can make the reassuring claim that where I am inaccurate, I am at least definitively inaccurate.
![Heart | [heart]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/love.gif) your ![Green Alien | [Alien]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/alien.gif) with ![Good Stuff | [The good stuff]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/vegemite.gif) and ![Beer | [beer]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/beer.gif)
Sonork - 100.10414 AcidHelm
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since ppv=(int**)&obj;, ppv point to the begin of obj object, cos' the obj contains a virtual function, it contains a virtual ptr(__vptr), and i'm using vc6, the microsoft complier set the vptr at the begin of the object, so ppv is pointed to the vptr when finishing the assignment.
The memory just like below:
----------
| vptr |
----------
|int _a |
----------
CBase obj;
(each column is 4 bytes)
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I still don't understand what you're trying to test.
--Mike--
http://home.inreach.com/mdunn/
While I can't be correct on all matters, I can make the reassuring claim that where I am inaccurate, I am at least definitively inaccurate.
your with and
Sonork - 100.10414 AcidHelm
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Michael Dunn wrote:
I still don't understand what you're trying to test.
You are not the only one Michael, you are not the only one.
Nish
Sonork ID 100.9786 voidmain
www.busterboy.org
Nish is a BIG fan of Goran Ivanisevic
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the main purpose of my program is to call the virtual function by using the ppv pointer. the ppv is the virtual pointer points to the virtual table, and the virtual table contains the address(es) of the virtual function(s) in the class, so the *ppv is pointed to the virtual table, and the **ppv[0] points to the first virtual function address, **ppv[1] points to the second virtual function address.
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That's not how you call virtual functions. You use a pointer to a C++ object, and call methods thru that pointer.
class CBase
{
public:
virtual void VFunction()
{
printf("Hello, VFunction.\n");
}
int _a;
};
int main()
{
CBase obj, *pobj = &obj;
pobj->VFunction();
}However none of this makes a difference because without a hierarchy of derived classes, you're not using polymorphism, which is what virtual functions are for.
--Mike--
http://home.inreach.com/mdunn/
While I can't be correct on all matters, I can make the reassuring claim that where I am inaccurate, I am at least definitively inaccurate.
your with and
Sonork - 100.10414 AcidHelm
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Thank you very much. i knew this way of calling the virtual function. but now i want to implement that by another way. and i know it really works. i just don't know how to do the last step -- if you got the function address, how to assign it to a function pointer, just like:
void* address; // or int* address;
void (*pFunc)();
...
pFunc = address; // address contains a function address. but pFunc cannot be assign like this expression.
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Oh, OK, you just want a pointer to point at a member function.
class CBase
{
public:
void func()
{
printf("Hello, VFunction.\n");
}
};
int main()
{
CBase obj, *pobj = &obj;
void (CBase::*pBaseMethod)() = CBase::func;
obj.*pBaseMethod();
pobj->*pBaseMethod();
}The .* or ->* operator dereferences the function pointer.
--Mike--
http://home.inreach.com/mdunn/
While I can't be correct on all matters, I can make the reassuring claim that where I am inaccurate, I am at least definitively inaccurate.
your with and
Sonork - 100.10414 AcidHelm
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Haaaa... thank you again. but what i really want to know is how the virtual pointer and the virtual function table work inside the class.(actually, virtual pointer is inside the class, virtual function table is not)
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Dear All,
In my project i have to get the ClassId and ProgId for an ActiveXControl,Can any one help me how to search the registry for ClassID and ProgId through VC++ programme.
With special thanks![Rose | [Rose]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/rose.gif)
akshay
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Use CLSIDFromProgID. In this case, the ProgID is the Name of the interface.
e.g.
[ccode]
CLSID ID;
CString strProgID = "Program.Interface";
HRESULT hr = CLSIDFromProgID( strProgID .AllocSysString(), &ID); // GUID is in ID if successful.
[/ccode]
Hope this helps,
Bill
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Thank you for your idea,today i have an holiday i will check this code on monday,
sir,Is there any MFC class for Registry search.
Actually i have to write a function for getting ClassId and progId as like
Myfunction("c:\mycoment.ocx")
{
//this function will return ClassId and ProgId for
//corresponding ocx from registry
}
Please help me sir,because i didn't have much knowledge on registry search
once again thank you for your reply
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Use the following API calls
(1) RegOpenKeyEx
(2) RegQueryValueEx
(3) RegEnumValue
(4) RegEnumKeyEx
Nish
Sonork ID 100.9786 voidmain
www.busterboy.org
Nish is a BIG fan of Goran Ivanisevic
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Thank you for your Sugesstion.
Is there any specific MFC class for Registry Search.
Thanks in advance
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akshay wrote:
Is there any specific MFC class for Registry Search
Not that I am aware of.
Basically you'll need to enumerate all the keys and then enumerate all the values.
Even if you find a class, that's all what even the class would do for you.
I recommend Joe Newcomer's class if you dont want to do the enumerating and querying usign API
Here is the link
http://www.codeproject.com/system/registry_class.asp
Nish
Sonork ID 100.9786 voidmain
www.busterboy.org
Nish is a BIG fan of Goran Ivanisevic
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I've check everywhere I can, but how do I generate a small floating text display when the mouse cursor rest for a while over the client area?
Just like when you rest the mouse cursor over a variable in VC++, its class or type is displayed in a small info box much like the tooltip. 
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Take at look at this: http://www.codeproject.com/miscctrl/multiline_titletips.asp
Chen Venkataraman
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Thanks! Problem solved 
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Hi,
Can anyone tell me how can I
open a Modal dialog , but that
is hidden ?
Thanks
San
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Yes, use DoModal
In the InitDialog use ShowWindow with SW_HIDE.
Best Regards
Carlos Antollini.
Sonork ID 100.10529 cantollini
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Hello, the codegurus around the world.
Are you sure that ShowWindow (SW_HIDE) works?
I think that the controls on the dailog is hidden by ShowWindow (SW_HIDE)
, but the dialog isn't hidden by ShowWindow(SW_HIDE) in OnInitDialog().
In fact, I try to do this by myself, but this didn't work.
So, I use MoveWindow, and use the size of the dialog as zero.
(look like hidden )
Or, you are sure.
Have a nice day!
-Masaaki Onishi-
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Masaaki Onishi wrote:
Are you sure that ShowWindow (SW_HIDE) works?
You are correct. For a modal dialog putting ShowWindow(SW_HIDE) in the OnInitDialog won't have the expected effect. But you can try this. Put this in the OnInitDialog.
SetTimer(5000,5000,0);
You can change the 5 seconds to 3 seconds or even 1 second. But don't make it lesser than that, because we need to make sure the dialog has comeup on screen.
Now in the OnTimer(UINT nIDEvent) do this :-
if(nIDEvent==5000)
ShowWindow(SW_HIDE);
You might want to use KillTimer to prevent the timer function being activated repeatedly and meaninglessly.
But mind you, once you've hidden the window, the user cannot do anything to it. I hope you are sure, this is what you wanna do, because I see no reason why anyone would want to hide their modal dialog.
Regards
Nish
Sonork ID 100.9786 voidmain
www.busterboy.org
Nish is a BIG fan of Goran Ivanisevic
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Hello, the codegurus around the world.;)
Thanks, BusterBoy.
However, I have already implemented this kind of code in my project.
In my case, I use Timer to show the dialog hidden by MoveWindow
in OnInitDialog().
In fact, if the other ppl succeed in for the dialog hiding
by ShowWindow (SW_HIDE) in OnInitDialog(), I must consider that my code
may be something wrong with others in OnInitDialog().
Have a nice day!
-Masaaki Onishi-
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A hidden modal dialog will make your app unusable, since modal means the parent window is disabled. So you'll end up with a disabled main window and no way to interact with the dialog.
--Mike--
http://home.inreach.com/mdunn/
While I can't be correct on all matters, I can make the reassuring claim that where I am inaccurate, I am at least definitively inaccurate.
your with and
Sonork - 100.10414 AcidHelm
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