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Hi
class A
{
public:
virtual void fun()=0
{
cout<<"hai";//code inside in an pure virtual function
}
};
this works in VC++.(code inside an pure virtual function)
Is the same thing work in other compilers of C++
VIBIN
"Fool's run away,where angle's fear to tread"
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I have the following questions :
1.Which version of VC++ compiler did you use?
2.What is your understanding of pure virtual functions?
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the version is VC++6.0
My understanding of Virtual fuction
It creates an V table, which provides run time ploymorphism,
And an pure virtual function makes the calss an Abstract base class.
VIBIN
"Fool's run away,where angle's fear to tread"
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Great,
As for i am aware, the compiler should not allow it, and even if it allows what is the use of it when the class is abstract.
P.S: I have checked with VC++7.0, it gives an error
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The error will only be displayed if you try to actually instantiate the class:
A myInstance; // This will fail
But VC6 is also a very old compiler and not fully compliant to the actual standard.
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vibindia wrote: Is the same thing work in other compilers of C++
That sounds like a try-it-and-see question.
"A good athlete is the result of a good and worthy opponent." - David Crow
"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne
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I believe that it is completely valid. Declaring a function as pure virtual does not mean that does not have an implementation, only that you have to provide one in a derived class.
This can (and has) been used to force developers to customize behavior for their derived classes, but still provide an implementation in the base class.
It should only give you an error if you try to directly instantiate an instance of that base class, or of a derived on that does not provide an implementation for the PV function.
Of course, I could be wrong here...
Peace!
-=- James Please rate this message - let me know if I helped or not!<HR>If you think it costs a lot to do it right, just wait until you find out how much it costs to do it wrong!
Avoid driving a vehicle taller than you and remember that Professional Driver on Closed Course does not mean your Dumb Ass on a Public Road!
See DeleteFXPFiles
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In our app we have a resource manager which used a temporariy directory in the temp folder to store data while the application is runnning.
To preserve the integrity of our data we need to prevent the deletion of this folder while the application is running.
How could I lock the directory?
I'm thinking of win32 call like LockFile/LockFileEx, but I'm not sure what argument pass to these methods.
Any tips?
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Super Lloyd wrote: How could I lock the directory?
Make it read-only using (I think) SetFileAttributes(), or change the folder's permissions via an ACL.
"A good athlete is the result of a good and worthy opponent." - David Crow
"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne
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interesting, will test that....
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See SetFileSecurity does any help?
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This is a strange error. First time i've seen it, anyone know a way around it?
[b]
compiler limit : too many exception handler states in function 'function'. simplify function
I read http://msdn2.microsoft.com/en-us/library/673fh3hz(vs.71).aspx on MSDN's site and basically anything above 1920 is a no no. Other than making a new function or something like that, anyone have another solution? Thanx in advance!
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Can you show the code?
Steve
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Is this VS 2003? If so: http://support.microsoft.com/kb/884888[^].
Try breaking the function into two or more smaller functions (welcome to refactoring!) and see if that helps.
Peace!
-=- James Please rate this message - let me know if I helped or not!<HR>If you think it costs a lot to do it right, just wait until you find out how much it costs to do it wrong!
Avoid driving a vehicle taller than you and remember that Professional Driver on Closed Course does not mean your Dumb Ass on a Public Road!
See DeleteFXPFiles
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dellthinker wrote: Other than making a new function or something like that, anyone have another solution?
Simplify expressions by assigning common subexpressions to temporary variables.
"A good athlete is the result of a good and worthy opponent." - David Crow
"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne
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Can you show snippet code?
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Hi, I know Visual Studio has a way to detect when the developer is entering a comment by typing '///'.
I'm currently using Visual C++ 2005 Express Edition and it does not create the comment template I was hoping for.
such that typing "///" nets something along these lines:
/**
* comment:
*
* Params:
**/
Can anyone tell me what the key combination is or where to turn it on?
Is it even available in Visual C++ 2005 XE?
Thanks in advance.
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hi,
Is there any way to change the cursor of the container application from the activex control.
Regards,
John,
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NOTIFYICONDATA notifyData;<br />
notifyData.cbSize = sizeof(notifyData);<br />
notifyData.hWnd = hwnd;<br />
notifyData.uFlags = NIF_ICON | NIF_TIP | NIF_MESSAGE | NIF_STATE;<br />
notifyData.uCallbackMessage = MSG_STATUSICON;<br />
notifyData.hIcon = LoadIcon(GetModuleHandle(NULL), MAKEINTRESOURCE(IDI_ICON1));<br />
::strcpy((char*)notifyData.szTip, "hello"); <-- not working<br />
::strcpy((char*)notifyData.szInfo, "blablabla");<br />
<br />
char tp [128] ;<br />
::strcpy(tp,(char*)notifyData.szTip);
<br />
Shell_NotifyIcon(NIM_ADD, ¬ifyData);
instead of hello im getting gibberish on my icon ToolTip ..long string looks like chinese.
something wrong with this line?
::strcpy((char*)notifyData.szTip, "hello");
thank you
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Lamefif wrote: notifyData.uFlags = NIF_ICON | NIF_TIP | NIF_MESSAGE | NIF_STATE;
What if you remove NIF_STATE?
"A good athlete is the result of a good and worthy opponent." - David Crow
"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne
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Lamefif wrote: something wrong with this line?
::strcpy((char*)notifyData.szTip, "hello");
If it's a unicode build then yes, there's something wrong with that line 
I would recommend NOT using casts unless you need to. Write code without the casts. If the
compiler complains, then investigate why.
For a Unicode build, that line should be something like:
// Unicode only
::wcscpy(notifyData.szTip, L"hello");
or better yet
// generic
_tcscpy(notifyData.szTip, _T("hello"));
If this is indeed the problem, had you omitted the casts to char*, the compiler would have let
you know.
Mark
-- modified at 14:23 Monday 16th July, 2007
Mark Salsbery
Microsoft MVP - Visual C++
"Great job team! Head back to base for debriefing and cocktails."
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thank you mark
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You're welcome
Also check out DavidCrow's reply...you are using a flag that indicates members of the struct are
valid but you didn't show those members being initialized.
Cheers,
Mark
Mark Salsbery
Microsoft MVP - Visual C++
"Great job team! Head back to base for debriefing and cocktails."
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How to make sure the LPCRITICAL_SECTION i have is a valid one ?. ie, suppose some other thread called a DeleteCriticalSection() on the same pointer then the pointer becomes invalid and the behaviour is undefined. So how to make sure this has not happend.
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