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Hello.
I have a buncha files that were written in C in unix. It uses a few libraries that I don't have using Visual Studio 2005 (Win). How do I compile the files into a .dll under VC++ in Win?
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If these files use unix libraries, then there is no way to port them for windows, unless you rewrite the parts which are system dependant.
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Cedric Moonen wrote: If these files use unix libraries, then there is no way to port them for windows, unless you rewrite the parts which are system dependant
i have heard of some minigw type stuff who could compile library written in unix for windows enviornment!
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ThatsAlok wrote: i have heard of some minigw
Yes, but he asked specifically for VC++2005.
*Probably* he can compile and run his Unix-code with Mingw. It then remains a Unix-Program on a Wrapper around Windows.
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Hi, i have an SDI App, and i want to add some buttons dynamically(by NEW operator) to CFormView based Form. I don't know how to add my code to those buttons.
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zarraza wrote: don't know how to add my code to those buttons.
When a button is clicked the button will send a WM_COMMAND message to the parent and the wparam of that message will be having BN_CLICKED.
Suppose you created the button with id 1234, do the processing as follows
overied the oncommand function of the CFormview through class wizard. Then inside that function check whether the HIWORD is BN_CLICKED and LOWORD is 1234..
<br />
if( HIWORD( wParam ) == BN_CLICKED && LOWORD(wParam) == 1234 )<br />
{<br />
AfxMessageBox( "Buttom is clicked" );<br />
}
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Further to this you can utilise the MFC MessageMap to do this. Just add the ON_BN_CLICKED manually outside of the AFX_MSG_MAP comments. To keep things neat I always place my manual stuff relative to the MFC Wizard stuff here shown in italics
in the class declaration
//}AFX_MSG
void OnMyDynamicButton();
DECLARE_MESSAGE_MAP()
in the message map
//}}AFX_MSG_MAP
ON_BN_CLICKED(1234, OnMyDynamicButton)
END_MESSAGE_MAP()
void CMyFormView::OnMyDynamicButton()
{
// your button code
}
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Hello
I am writing a class and need a way to catch the exception when some variables are used without being initialized. I'm working in standard c++ but compile it in visual c++ 2005. As far as I can remember I would use this technique in vc6.0:
<br />
if(class_variable==NULL)<br />
but now i get the compile error: "Run-Time Check Failure #3 - The variable 'class_variable' is being used without being defined. "
I will wait for your answer and would appreciate it.
by regards Shahin Namini
-- modified at 16:10 Wednesday 17th October, 2007
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shahin namini wrote: I am writing a class and need a way to catch the exception when some variables are used without being declared.
Declared? Do you mean initialized? Otherwise you would get a compiler error.
shahin namini wrote: "Run-Time Check Failure #3 - The variable 'class_variable' is being used without being defined. "
Hehe, so even MS people don't know the difference between "defined" and "initialized".
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you are right and thanks for notation. The first one was my blunder and i corrected it. anyway have got any idea about my problem?
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why not just initialize them ?
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This class does the computations of a 2d ellipsoid, modelling the earth and has lots of variables which are very likely not being initialized. so I thought I would throw the exception whenever i call a function which requires one of the parameters not being initialized yet. have got any comment?
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How would you differentiate between an initialized variable vs. a variable having an invalid value?
"Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for, in order to get to the job you need to pay for the clothes and the car and the house you leave vacant all day so you can afford to live in it." - Ellen Goodman
"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne
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the is no concept of "uninitialized" built into C++. either you initialize the variables yourself or you live with the effects of random garbage in your program.
just initialize the variables.
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shahin namini wrote: if(class_variable==NULL)
//throw the exception
If the exception is thrown, that means that class_variable was initialized (to NULL).
"Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for, in order to get to the job you need to pay for the clothes and the car and the house you leave vacant all day so you can afford to live in it." - Ellen Goodman
"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne
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don't care for words. Whatever you call it, I am seeking for the answer!
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Hello,
If I need to use a function in a C library that I can't modify, let's say:
extern "C"
{
void register_callback(void (*callback) (void));
}
... if I also have a class like this:
class MyClass
{
int m_counter;
public:
MyClass() : m_counter(0) {}
void OnEvent()
{
m_counter++;
}
}
Is there any solucion to use MyClass::OnEvent with the funcion register_callback()? In other words, I would like to do something like this (Of course this doesn't work):
int main (void)
{
MyClass my;
register_callback(&(my.MyClass::OnEvent))
}
It's very easy to make MyClass a singleton and define MyClass::OnEvent() as 'static' or use a singleton inside MyClass, which is enough in almost all the cases but I don't want to modify MyClass at all.
I've tried this one:
int main (void)
{
register_callback(sigc::mem_fun(*this,&MyClass::OnEvent));
...
}
That doesn't work. One of the problems is that sig::mem_fun() return an object created in the stack and the parameter for register_callback must be a 'const' one.
Thank you in advance,
Miguel
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You can't do this cleanly in C++. I.e. member functions cannot be used where static functions are specified. If you want to hack things and possibly add some cryptic assembler, then it's possible. But that does violate the constraints of the language. There are some articles here on CP that demonstrate this kind of hack if you want to delve into it.
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Thank you Jim, you're right. I have read a lot about this and I haven't find anything useful.
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the callback function doesn't take any parameters ? that sucks.
for this very reason, whenever we do a callback hook in one of our libraries, we specify our that the callback function must take at least one parameter large enough to hold a pointer. for example:
typedef BOOL (CALLBACK* IS40_SourceCloseFn)(const IS_CALLBACK_DATA uUserInfo);
you can pass a 32-bit value into the 'register callback' function and all the callback calls will pass that parameter back to you. so, you use an object pointer as the 32-bit value, the lib passes that value to the callback function, and you cast it back to the object type in the callback.
otherwise, you're stuck using global variables in the callback (and tricky synchronization schemes to make sure only one call is in there at a time).
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The callback function and MyClass can't be modified. I've make it up so in order to focus the problem.
This is the code that you can't modify:
extern "C"<br />
{<br />
void register_callback(void (*callback) (void)); <br />
}
... if I also have a class like this:
class MyClass<br />
{<br />
int m_counter;<br />
public:<br />
MyClass() : m_counter(0) {}<br />
void OnEvent() <br />
{<br />
m_counter++;<br />
}<br />
}
Thanks
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elmendavies wrote: extern "C"
{
void register_callback(void (*callback) (void));
}
Is this the signature of the real callback function? If it takes a context argument (generally void*) then the solution is simple and well known.
Steve
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I've make it up. It's not a real library function but it could be. Remember for example the signal function in UNIX and the definition of its callback:
http://www.hmug.org/man/3/signal.php
How to solve it?
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If sizeof(int) is big enough to hold a pointer then something like the following will work.
extern "C"
{
void register_callback(void (*callback)(int), int arg);
}
class MyClass
{
int m_counter;
public: MyClass() : m_counter(0) {}
void OnEvent()
{
m_counter++;
}
}
void MyClassOnEventThunk(int arg)
{
MyClass *pInstance = reinterpret_cast<MyClass*>(arg);
pInstance->OnEvent(pInstance);
}
MyClass g_inst;
register_callback(&MyClassOnEventThunk, reinterpret_cast<int>(&g_inst));
If sizeof(int) is ***NOT*** big enough to hold a pointer you will have to maintain a mapping yourself.
Steve
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