C / C++ / MFC

30-Jan-03 23:16

Hi, everyone!

I do not understand what is the function of new operator
in the following example. Especially this statement,

--------
(void)new (pint) Elem(10);
--------

Another question, when compiling, a warning jumps out like the
following, I want to know how to avoid the warning.

Thanks in advance,
George

--------
c:\program files\microsoft visual studio\myprojects\testnew\testnew.cpp(25) : warning C4291: 'void *__cdecl operator new(unsigned int,void *)' : no matching operator delete found; memory will not be freed if initialization throws an exception
--------

#include <iostream.h>

inline void* operator new(size_t, void* ptr) { return ptr;}

class Elem{
public:
Elem(int a)
{
data = a;
}

public:
int getData()
{
return data;
}

private:
int data;
};

void main()
{
int* pint = new int[2 + sizeof(Elem)];
(void)new (pint) Elem(10);
Elem* elem = (Elem*)pint;
cout << elem->getData() << endl;
delete pint;
}

Hans Ruck31-Jan-03 1:00

Hans Ruck

31-Jan-03 1:00

(void)new (pint) Elem(10);

Constructs a new Elem object at the address pint. Run it step by step with a breakpoint in new's body and you'll see what is all about.

rechi

George231-Jan-03 3:16

31-Jan-03 3:16

Hi, Bogdan buddies!

I do not understand why we add a "(void)" before
the statement?

Thanks in advance,
George

Hans Ruck31-Jan-03 3:35

Hans Ruck

31-Jan-03 3:35

George2 wrote:
I do not understand...

Neither do i. The call has right value so the conversion appears to be useless since there's no variable to receive it.

rechi

George231-Jan-03 4:28

31-Jan-03 4:28

Hi, Bogdan pal!

The return type of new operator is void*, so
I think we should use

--------
(void*) ...
--------

other than
--------
(void) ...
--------

Since void* is a C++ data type and void is not a C++ data type. What is your opinion?

Thanks in advance,
George

Anonymous31-Jan-03 5:18

Anonymous

31-Jan-03 5:18

Perhaps it's to get it rid of a compile warning. Leave it out and see if there is one.

George231-Jan-03 17:52

WIN32 SDK : GetWindowDC works, GetDCEx doesn't

31-Jan-03 17:52

Thanks, Anonymous buddies.

I have tried and you are right. Can you tell
me why?

George

30-Jan-03 23:11

I am implementing a skin based tool kit.
When repainting the frame of a window,
i catch WM_NCPAINT message then get window's
device context :

case WM_NCPAINT:
{
  HDC hdc = NULL;
  if( wparam==1 )
    // it returns a valid DC
    hdc = GetWindowDC( hwnd );
  else
    // it always returns NULL !!!
    hdc = GetDCEx( hwnd, (HRGN)(wparam), DCX_WINDOW|DCX_INTERSECTRGN );

  // custom frame painting
  paintFrame( hdc );

  ReleaseDC( hwnd, hdc );  
}

The 'GetDCEx line' is taken from MSDN.

I use MSVC++7 under winXP
Thanks for your help

Replacing and resizing of the controls in formview to bestfit of Monitor on change system resolution

sulaxan30-Jan-03 22:11

sulaxan

30-Jan-03 22:11

REQUIREMENT:: Application shud be sized to full monitor irrespective of the monitor size and current system resolution.
My APPLICATION:: Application is having four formviews in tabcontrol with many controls(AcitveX Lables and Buttons) on each forma view. My application is developed for best view in 15 inch and 800*600 resolution.

MY PROBLEM: i have written code to catch when resolution ic changed.and accorind to the new resolution m changing the each contols's client rect and moving the corresponding control to new client react. but reafreshing si becoming problem and some controls are painting over other controls.

Adi Narayana

Any good references?

dsuratman30-Jan-03 20:57

dsuratman

30-Jan-03 20:57

Hi All,
I'm currently a firmware engineering and trying to get into software programming (using C++ for right now). I've decided to create a simple text editor as my first project.

Does anybody know any good references out there on this topic in particular and Windows programming in general?

Any suggestion on better projects for beginners?

Thanks y'all

Dody

LittleYellowBird30-Jan-03 23:51

LittleYellowBird

30-Jan-03 23:51

onezerocode wrote:
I'm currently a firmware engineer

Snap! I moved from firmware to software too, so I thought I would answer your question. I'm still a novice really so others may have something more usefull to say.

I started with the book 'SAMS Teach Yourself Visual C++' and I found it very poor, it didn't expain much just took you through some examples (very briefly).

Next I got the book 'Practical Visual C++' by Bates & Tompkins, this was much better, it assumes that you know very little and explains a fair ammount.

Lastly, I am currently reading 'Programming Windows with MFC' by Jeff Prosise, this is an excelent book it talks alot about what is actually going on - I like that, coming from a firmware/hardware background I want to know what is 'under the hood', but you need to understand C++ first as it does not explain this.

Hope that helps, good luck Smile | :)

,

Ali

Abbas_Riazi31-Jan-03 0:13

Abbas_Riazi

31-Jan-03 0:13

Programming MFC (written by Jeff Prosise) is a good reference.
A. Riazi

Lhenno Ferrari31-Jan-03 0:22

Lhenno Ferrari

31-Jan-03 0:22

Looking for a good C++ reference book ??? "Thinking in C++" rocks, take a look at http://www.mindview.net/Books/TICPP/ThinkingInCPP2e.html.

Also, for M$ Development, MSDN provide exelent references e documentation.

Hope it Helps !!!

?