C / C++ / MFC Discussion Boards

Moak24-Oct-02 3:46

24-Oct-02 3:46

If it's multithreaded... yeah! Just use a mutex.

Then only one thread can read/write the gloabl shared data, the other thread(s) have to wait until the shared data is unlocked. Lock shared data as short as possible.

Re: Multithreaded server and a chat?

Daniel Turini24-Oct-02 3:52

Daniel Turini

24-Oct-02 3:52

A critical section can handle the same and is faster and easier to setup. And safer too, if you are the kind of programmer who forgets to CloseHandle() Smile | :)

Q261186 - Computer Randomly Plays Classical Music

Re: Multithreaded server and a chat?

Moak24-Oct-02 5:52

Moak

24-Oct-02 5:52

ah yes... I use it too.

CCriticalSection m_NodesListAccess; //synchronize access on lists/maps

m_NodesListAccess.Lock();			
/* do something */
m_NodesListAccess.Unlock();

For some (strange) safety reasons I use it even in my async socket class, but I might be overprotective.... Smile | :)

Re: Multithreaded server and a chat?

Rickard Andersson²⁰24-Oct-02 9:18

Rickard Andersson²⁰

24-Oct-02 9:18

Moak wrote:
but I might be overprotective

yeah, like Britney Spears... LOL! Smile | :)

So if I access a global std::list between m_NodesListAccess.Lock(); and m_NodesListAccess.Unlock(); all other threads have to wait untill current thread has m_NodesListAccess.Ublock();?????

Cool... but... I'm not using MFC... I think this is an MFC class, right?
So, how to do it in Win32 API??

Rickard Andersson@Suza Computing
C# and C++ programmer from SWEDEN!
UIN: 50302279
E-Mail: nikado@pc.nu
Speciality: I love C#, ASP.NET and C++!

Re: Multithreaded server and a chat?

Rickard Andersson²⁰24-Oct-02 9:33

Rickard Andersson²⁰

24-Oct-02 9:33

Rickard Andersson wrote:
So, how to do it in Win32 API??

Found an article here on CP!

Rickard Andersson@Suza Computing
C# and C++ programmer from SWEDEN!
UIN: 50302279
E-Mail: nikado@pc.nu
Speciality: I love C#, ASP.NET and C++!

/OPT:REF

stevenson24-Oct-02 3:13

stevenson

24-Oct-02 3:13

Hi,
I cannot got my dll because of this

Creating library Release/AutoRecAndSave.lib and object Release/AutoRecAndSave.exp
LINK : warning LNK4089: all references to "comdlg32.dll" discarded by /OPT:REF

Tell me how to fix it.

Thank u in advance

Extreme programming. Do the No.1

Re: /OPT:REF

Mike Nordell24-Oct-02 3:32

Mike Nordell

24-Oct-02 3:32

What is there to fix?

Somewhere in your code you have included a line

#pragma comment(lib, "comdlg32")

but in the end (at link-time) it turns out you never used any function from that library/DLL and therefore it's discarded.

Re: /OPT:REF

stevenson24-Oct-02 3:56

stevenson

24-Oct-02 3:56

I mean, I can't make dll because of this, cannot MAKE DLL.

Extreme programming. Do the No.1

Re: /OPT:REF

User 665824-Oct-02 4:21

User 6658

24-Oct-02 4:21

This is only a warning, so this can't be the cause that you can't build the DLL. I have this warning in a few DLL projects as well, but all compile fine anyway.

modified 12-Sep-18 21:01pm.

Re: /OPT:REF

Joe Woodbury24-Oct-02 7:03

Joe Woodbury

24-Oct-02 7:03

To get rid of this warning, go to the command line section of the linker options and add

/IGNORE:4089

But this is just a warning and is completely benign, so if you aren't linking this isn't the problem.

Re: /OPT:REF

Michael Dunn24-Oct-02 9:49

Michael Dunn

24-Oct-02 9:49

Why do you say turn off the warning? Why not fix the problem that's causing the warning?

--Mike--
"I'd rather you just give me a fish today, because even if you teach me how to fish, I won't do it. I'm lazy." -- Nish
Just released - 1ClickPicGrabber - Grab & organize pictures from your favorite web pages, with 1 click!
My really out-of-date homepage
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Re: /OPT:REF

Alvaro Mendez24-Oct-02 10:09

Alvaro Mendez

24-Oct-02 10:09

I'd say because it's not worth it. Most warnings should be addressed and fixed, but a few, like this one are just not worth the trouble. I can list you a couple of other compiler warnings which I've disabled:

4786: identifier was truncated to '255' characters in the debug information
4355: 'this': used in base member initializer list

Do you think it's worth fixing these? If so, how would you do it?

Regards,
Alvaro

There is much pleasure to be gained from useless knowledge. - Bertrand Russell

Re: /OPT:REF

Joe Woodbury24-Oct-02 11:28

Joe Woodbury

24-Oct-02 11:28

Michael Dunn wrote:
Why not fix the problem that's causing the warning?

Because often you can't for this specific warning which is generated because the linker COMDAT optimization made the library no longer necessary, though it was before the optimization.

[Link message] 4089 is an purely informational message and should be labeled as such--it is not a warning in any commonly accepted way. In other words, the presence or absence of this warning has no bearing on whether an executable will or will not work.

how can I make a multirow CPropertySheet?

DanYELL24-Oct-02 3:09

DanYELL

24-Oct-02 3:09

I have alot of pages. I can only seem to get 16 pages on one row. Is there away to make ten pages on one row and ten more pages on another row?

Please, any response any one can give me will be greatly appreciated.

Sincerely,
Danielle (an overworked graduate student)

Re: how can I make a multirow CPropertySheet?

Mike Nordell24-Oct-02 3:47

Mike Nordell

24-Oct-02 3:47

You mean something like this?

Re: how can I make a multirow CPropertySheet?

DanYELL24-Oct-02 4:54

DanYELL

24-Oct-02 4:54

Yes, yes, yes. How? How? How?

Re: how can I make a multirow CPropertySheet?

Ravi Bhavnani24-Oct-02 5:10

Ravi Bhavnani

24-Oct-02 5:10

I fake it by padding the tab names with spaces. Not foolproof, but it works almost all the time.

/ravi

Let's put "civil" back in "civilization"
http://www.ravib.com
ravib@ravib.com

I want that TabCtrl!

solosnake24-Oct-02 2:55

solosnake

24-Oct-02 2:55

Hello

I want to add to my application the type of tabbed control that can be seen in MSVC as the 'Workspace' view. Its the tabs with the classview/resource/file tree's that's normally on the rhs of MSVC. How do I do this?

I'm using the doc-view architecture, and I want this CTabCtrl to be in one of two windows in a splitter wnd. It will be used to select between differing views of the data set that is displayed graphically in the rhs split window. There will be a fixed number of viewingmodes, each corresponding to a tab in the lhs tab ctrl.

Could anyone explain to me the sequence of classes I need to create to achieve this type of control? Can each of the tabs in the control represent a 'CView' derived class? Where should I attach them to the tab-ctrl?

All help or comments appreciated. Please don't redirect me to the (great) tab control samples that codeproject has : none of them are what I need, I've looked at them all.

Cheers,

- solosnake

Sockets without MFC/HWNDs or Spin-Locks?

Phil Speller24-Oct-02 2:07

Phil Speller

24-Oct-02 2:07

MFC's ASyncSocket class provides a wrapper around a Win32 socket and adds functionality to detect events (such as connection, packet received etc). Now I'm aware that a similar method can be performed using plain winsock programming and the use of WSAAsyncSelect. However, it requires the use of a window to receive events (CAsyncSocket does it like this as well doesn't it?). I've seen code that sets up a thread and just waits on recv() using a spin-lock - this seems to go against the grain with me though. I have noticed the select() fn, but I'm not sure if it would truly be thread friendly or would just hide a spin-lock. So, to my question: Is it possible to detect an event from a Socket without resorting to window messages or requiring a spin-lock?

Phil

Re: Sockets without MFC/HWNDs or Spin-Locks?

Stephane Rodriguez.24-Oct-02 3:46

Stephane Rodriguez.

24-Oct-02 3:46

A website[^] you'll love.

How low can you go ?
(MS rant)

Re: Sockets without MFC/HWNDs or Spin-Locks?

JT Anderson24-Oct-02 5:54

JT Anderson

24-Oct-02 5:54

You might find WSAEventSelect interesting.

--------
There are 10 types of people in this world. Those who know binary and those who don't.

OwnerDraw ListCtrl problem - help!

Yaron Nir24-Oct-02 1:57

Yaron Nir

24-Oct-02 1:57

Hi all,

I have an owner draw list ctrl.

i want to force a vertical scroll to be shown when the dialog
that the list sits on appears.
this is the code i've tried :

ListView_SetExtendedListViewStyle(m_lc.m_hWnd,
LVS_EX_FLATSB|LVS_EX_FULLROWSELECT );

now i've inserted some columns and then:

m_lc.ModifyStyle(0,WS_VSCROLL);
m_lc.SetScrollRange(SB_VERT,0,100);
m_lc.SetScrollPos(SB_VERT,0);
m_lc.ShowScrollBar(SB_VERT);

this doesn't show the vertical scroll bar.
the bar only show when the limit of inserted items succeeds.

can any1 show me what to do in order to force the scroll bar?

thanks in advanced

Yaron

Ask not what the application can do for you, ask what you can do for your application

Reading a Wav Header

carrie24-Oct-02 1:37

carrie

24-Oct-02 1:37

Hello, I'm on the beg again Smile | :)

I'm trying to read in the header of a wav file. My code so far is..

	<br />
struct<br />
{<br />
	WORD wFormatTag; // Format category<br />
	WORD wChannels; // Number of channels<br />
	DWORD dwSamplesPerSec; // Sampling rate<br />
	DWORD dwAvgBytesPerSec; // For buffer estimation<br />
	WORD wBlockAlign; // Data block size<br />
} FormatChunk;<br />
<br />
	char ch[1];<br />
	CFile waveFile;<br />
	if(waveFile.Open(wavName,CFile::modeRead|CFile::typeBinary)==FALSE)<br />
	{<br />
		TRACE("Error opening file");<br />
		return NULL;<br />
	}<br />
<br />
	//read till we get to the start of above chunk header<br />
	while(1)<br />
	{<br />
		waveFile.Read(ch,1);<br />
		TRACE("%c\n",ch[0]);<br />
		if(ch[0] == 'E')<br />
			break;<br />
	}<br />
<br />
	waveFile.Read(&FormatChunk,sizeof(FormatChunk));<br />
<br />
	DWORD temp = FormatChunk.dwAvgBytesPerSec;<br />
	//FormatChunk.dwAvgBytesPerSec holds the sampling rate <br />
	TRACE("Sampling rate is : %ld\n",temp);<br />
	TRACE("wChannels is : %0.2d\n",FormatChunk.wChannels);<br />
//	TRACE("format tag is : %s\n",FormatChunk.wFormatTag);<br />
<br />
	waveFile.Close();<br />
	return temp;

Ignore the ugliness of it please Smile | :)

My problem is reading in the wChannels value from byte offset 16, its a 2byte value. It should either be 0x10 or 0x20 in the file but I'm having problems reading it right. I've been playing with different variables to get it read right but all I get is either 16 for all of them or something like 8016 Frown | :(

Or have I totally missed the point and theres an API function out there that'll do it for me? Smile | :)

Thanks

Re: Reading a Wav Header

Phil Speller24-Oct-02 2:35

Phil Speller

24-Oct-02 2:35

Accoring to this[^] your FormatChunk structure is incorrect. It should be:

struct
{
DWORD wFormatTag; // Format category
DWORD dwFormatLen; // Length of format chunk - always 0x10
WORD wReserved; // Always 0x01
WORD wChannels; // Number of channels
DWORD dwSamplesPerSec; // Sampling rate
DWORD dwAvgBytesPerSec; // For buffer estimation
WORD wBytesPerSample;
WORD wBitsPerSample;
} FormatChunk;

Hope this helps,

Phil

Re: Reading a Wav Header

carrie24-Oct-02 2:50

carrie

24-Oct-02 2:50

Phil, thou art a god Smile | :)

Knew it had to be something stupid that I was doing, thanks for that link too Smile | :)

/me gets out my winsocks books to see about your question Smile | :)

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