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Indeed you're right: with respect thew original article, we made a big mistake  .
I think the right code to show the issue is, for instance
#include <iostream>
using namespace std;
class A
{
int a;public: A(){a=0;}
virtual int do_things(int a){this->a = a; return 0;}
};
class AB: virtual public A
{
int ab;
public:
AB(){ab=1; A * pA = this; pA->do_things(1);}
virtual int do_things(int a){A::do_things(a);this->ab = a+1; return 1;}
};
class AC: virtual public A
{
int ac;
public:
AC(){ac=2; A * pA = this; pA->do_things(2);}
virtual int do_things(int a){A::do_things(a);this->ac = a+2; return 2;}
};
class ABAC: public AB, public AC
{
int abac;
public:
ABAC(){abac = 4;}
virtual int do_things(int a){AB::do_things(a);AC::do_things(a);this->abac = a+4; return 4;}
};
int main()
{
ABAC abac;
return 0;
}
that produce the following memory layout:
- abac {abac=4 } ABAC
- AB {ab=2 } AB
- A {a=2 } A
- __vfptr 0x00415700 const ABAC::`vftable' *
[0] 0x0041122b [thunk]:ABAC::do_things`vtordisp{4294967292,0}' (int) *
a 2 int
ab 2 int
- AC {ac=4 } AC
- A {a=2 } A
- __vfptr 0x00415700 const ABAC::`vftable' *
[0] 0x0041122b [thunk]:ABAC::do_things`vtordisp{4294967292,0}' (int) *
a 2 int
ac 4 int
abac 4 int
If you try to compile and run it using #pragma vtordisp(off) then you get a runtime error (hence the usefulness of vtordisp).
Don't ask me the interpretation of vtordisp{4294967292,0}, at the moment I'm not able to... (though 4294967292 is -3, an offset?).
Perhaps the argument needs more investigation.
BTW was you [^]?
See also this one [^], it's interesting.
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
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Thanks CPallini,
I do not need to understand the exact details about what the numeric values in vtordisp means. I only need to use why the field is needed and its usage (how compiler and runtime utilize it).
According to the links, it is described when it is used, and it also conforms to your sample above.
My question is, why the field is needed and its usage and how compiler and runtime utilize it?
--------------------
but we have to add it to classes that inherit from a virtual base class and override virtual functions just in case the user does call a virtual function in the constructor or destructor.
--------------------
BTW:
I am not the person who posted,
http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=2128468&SiteID=1[^]
regards,
George
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hi
recently i have joined a company as software engineer on c++ (Embeded Systems)they are writing the code for thereself i.e they are not using ACTIVE X Controls like buttons, dialog boxes. just they are writing the code for the active x controls for their self in visual C++.i want to know how we will write the code for Active X Controls in detial.
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You can use MFC, ATL or just plain C. CP has a lot of articles about, for instance see [^]
BTW Try also to post in the right forum, the COM [^] one.
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
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No problem when using VC6.
With vs2008, it compiles but not take effect.
Extended style for CListCtrl:
LVS_EX_HIDELABELS|LVS_EX_SINGLEROW
I've tried to define WINVER and _WIN32_WINNT higher as
#define WINVER 0x0600
#define _WIN32_WINNT 0x0600
but also no effect.
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Doest this [^] help?
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
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i am 3rd-year student of university.
i ready to do project which i can do~
so i am thinking what can i make~
and i want to make USB control system.
USB control system is allowing computer to use USB that is registered by administrator.
if you want to use USB in your computer, you should input your password.
but i just have idea , and i don't know what should i do first....
My friend don't know ...
so can you please give me tip and
recommand book which i can reference?
(i can do c, c++ not winapi or MFC)
firstly, i am sorry, i am from korea.
and i am not good in wriitting english so please understand~
Thank you everyone~
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Jung Seng Won wrote: USB control system is allowing computer to use USB that is registered by administrator.
if you want to use USB in your computer, you should input your password.
I don't know if it is a good idea. Anyway you probably have to go deep inside system internals. Maybe asking the Hardware / Device Drivers [^] will help.
Jung Seng Won wrote: but i just have idea , and i don't know what should i do first....
My friend don't know ...
so can you please give me tip and
recommand book which i can reference?
Probably because your idea is too ambitious. What about a simpler project?
Jung Seng Won wrote: (i can do c, c++ not winapi or MFC)
Hence you can do just console applications.
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
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hi,
I used mapobjects2.3 (ESRI product) to develop, In Application class
a error occur:
if (!ProcessShellCommand(cmdInfo)) // error occur when run at this line
return FALSE;
The tip as follow:
Debug Assertion Failed!
Program:E:\WMDQS\bin\WMDQS.exe
File:occsite.cpp
Line:161
For information on how your program can cause an assertion faile,see the Visual C++ documentation on assertion.
(Press Retry to debug the application)
Terminate Retry Ignore
press the "Terminate" button, display the next tip as follow:
Unhandle exception in WMDQS.exe(DAO350.dll):0xC0000005:Access Violation.
In fact in my paogram I use ADO to link my database not DAO. So I think that maybe mapobjects2.3 used dao350.dll. I had used regsvr32.exe
to regesit dao350.dll and Mo20.ocx, but it is no use. I had used GOOGLE
to search ,but I had not found the satisfactory resoult . How to solve this question?
My compile environment is :
Visual C++ 6.0 + sp 6, Windows XP sp2 (Simplified Chinese Version)
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clever101 wrote: (Press Retry to debug the application)
Maybe try that option and debug You should be able to see the cause of the assertion.
Mark
Mark Salsbery
Microsoft MVP - Visual C++
![Java | [Coffee]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/coffee.gif)
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Hi,
I want to login (a htmlpage in ie control)
But ,I don't know the id or name of the button
How to click the login button?
I found some code,but you must know the name or id of login button?
void SubmitPage(IHTMLElementCollection *pobjAllElement,CString strName)
{
CComPtrp Disp;
pobjAllElement->item(COleVariant(strName),COleVariant((long)0),&pDisp);
CComQIPtr pElement;
if(pDisp==NULL)
{
AfxMessageBox(strName + "????!");
}
else
{
pElement=pDisp;
pElement->click();
}
}
Thank you!
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for your question how to submit, try this; get the form element and submit form, IHTMLFormElement::Submit().
But what is your scenario how you are entering the login info without knowing the id?
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I dont know the login button's name or ID
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if the login button is of type submit, you can explicitly submit the form without knowing the button id using IHTMLFormElement::Submit() (refer for more handling) .
chinakknd wrote: I dont know the login button's name or ID
 this you already mentioned in your origial post, I am asking how you enter login info (login name login password) without knowing the ids. In order to automate such things I think you need to know the information of the elements.
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Here's a ridiculously simple question. What's the equivalent of SetCursor for MFC MDI child windows? I have looked through the documentation but can't find it. (I found the WaitCursor functions, but that's not what I want.)
How do I set and reset the cursor for an MFC MDI application?
Thanks.
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I need to have a C++ MFC project use an icon that has 8 bit alpha transparency ... not just 1 color transparency.
The furthest I've gotten is converting
m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME)
to
m_hIcon = (HICON)LoadImage(::AfxGetResourceHandle(), MAKEINTRESOURCE(IDR_MAINFRAME), IMAGE_ICON, 0, 0, LR_CREATEDIBSECTION);
and trying some variations on the last parameter such as LR_LOADTRANSPARENT.
Please help. Thanks!
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Is your icon already authored to be 32-bit?
If so, a simple load like this should work (don't use LR_SHARED if you want to destroy the icon yourself)...
m_hIcon = (HICON)LoadImage(::AfxGetResourceHandle(), MAKEINTRESOURCE(IDR_MAINFRAME), IMAGE_ICON, 0, 0, LR_SHARED);
Mark
Mark Salsbery
Microsoft MVP - Visual C++
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Hi everyone,
I'm trying to use some registry functions from the Windows API in a native C++ project.
The thing is that I'm getting an error that says RegGetValueA cannot be found in ADVAPI32.dll, but I'm not using that function. Instead I'm using RegQueryValueEx.
Anybody knows why this happens?
Thanks
rotter
The metaller programmer
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Nevermind. I found the problem.
I used the problematic function before and it seems it remained somewhere in the compiled code.
A rebuild solved it.
Thanks anyway
rotter
The metaller programmer
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I have the follwing code:
class MyStruct {
public:
std::string s;
};
class Test {
public:
operator std::string() const {
return std::string();
}
operator void* () const {
return NULL;
}
operator char () const {
return 'a';
}
};
It's nonsensical but bear with we. The idea is that the Test class should convert to various types, so the expression:
Test t;
std::string s = t;
compiles fine, where "s" is assigned whatever the result of Test::operator std::string().
Why then do I get compiler errors ( both on VC6 and VC8) when I do
Test t;
MyStruct m;
m.s = t;
It complains about "error C2593: 'operator =' is ambiguous"? What am I missing??!
If I remove the operator char() converter then it compiles fine. But why does this work in the first case and not the second?
¡El diablo está en mis pantalones! ¡Mire, mire!
Real Mentats use only 100% pure, unfooled around with Sapho Juice(tm)!
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VCF Blog
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It's not C++, is it string class (operator overloading) interaction with your ones.
Jim Crafton wrote: What am I missing??!
Nothing.
Jim Crafton wrote: If I remove the operator char() converter then it compiles fine. But why does this work in the first case and not the second?
Because of the string::= operator, that accepts a string as well a character, hence the ambiguity.
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
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OK, but why does the second example fail? It's also assigning it to a string class?
The only difference is that it's now a member variable.
m.s = t;
where "m" is a MyStruct type and m.s references the member variable MyStruct::s which is a std::string. So how is that any different than doing
std::string b = t;
The first one fails, the second one doesn't, yet both reference a std::string variable!
¡El diablo está en mis pantalones! ¡Mire, mire!
Real Mentats use only 100% pure, unfooled around with Sapho Juice(tm)!
SELECT * FROM User WHERE Clue > 0
0 rows returned
Save an Orange - Use the VCF!
VCF Blog
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