C / C++ / MFC

20-Jan-01 1:55

Sorry I misinformed you WINUSER.H, my apologies.

Norm

Joan M20-Jan-01 2:08

Joan M

20-Jan-01 2:08

Thank you very much! you has helped me a lot, this is very important in order to be more productive...

AlexMarbus21-Jan-01 12:26

AlexMarbus

21-Jan-01 12:26

If you don't know exactly where to look, you could also type the name in the VC editor, in this case WM_NOTIFY, rightclick on it, and select "Go to definition of..".
You'll see where it's defined, and the actual value of it.

--
Alex Marbus

Re: Opening the CD ROM drive

Michael Dunn20-Jan-01 5:30

Michael Dunn

20-Jan-01 5:30

You can also look it up in VC if you're debugging. In the Watch window, enter "78,wm" (or whatever number) and VC will display the corresponding WM_* symbol.

--Mike--
http://home.inreach.com/mdunn/
Is history an illusion caused by the passage of time, or is time an illusion caused by the passage of history?

Network game

20-Jan-01 0:54

I am working on a game, and I want it to have network play capabilities,
LAN preferrably and without the MFC. It's a very small game, so it shouldn't be to advanced to implement. Does anybody have any idea how I can do this? I have never done a network game before.

Thanks in advance. Smile | :)

Erik

Re: Network game

NormDroid20-Jan-01 1:39

NormDroid

20-Jan-01 1:39

Good book to start with is the "Winsock 2.0 Programming" by Lewis Napper - Highly Recommended.
If there are more than 2 players, I would recommend client-server. Where the clients connect to a running server app. You could use Winsock API direct or use the MFC wrapper classes (CAsyncSocket & CSocket).

Another strategy would to use DCOM and connection points, here you could start with Professional ATL Programming by Richard Grimes - Good book.

If could be even possible with SOAP, I don't have even knowledge to advise you on this one.

Look around on this site in the Internet Section also look in www.codeguru.com.

Good Luck

Opening the CD ROM drive

Ashman20-Jan-01 0:47

Ashman

20-Jan-01 0:47

Hi all,
I am writing an MFC app for my friend who finds it hard to open the CD ROM drive by pressing the buttons on the CD-DRIVE.
He has 3 drives, and I want individual ones to open by pressing the button Open.

Can I do this?
How?
Thanks
Ashman
PS: Please be detailed, Im rather dumb =)

24-Jan-01 2:56

You need to use the media control interface (MCI).
You can send strings or commands to the MCI to get things done.

Set CDAudio Door Open
Set CDAudio Door Close

I don't know how to address more than one CD this way.
Its different using the command API rather than the string API.

see also Microsoft knowledge base article: Q109371

Stephen

Small question about MFC\DIALOG

Ahmad19-Jan-01 21:01

Ahmad

19-Jan-01 21:01

-Enter and ESC keys close the dialog how i can stop it .
-How i can load accelerator from resource to MFC\DIALOG
i use loadaccelerator function but it didn't work.
thank you ...

Re: Small question about MFC\DIALOG

19-Jan-01 21:37

The best way is to try a keyboard Hook. That we you are totally in control of what's hapenning.

Re: Small question about MFC\DIALOG

Christian Graus19-Jan-01 23:09

Christian Graus

19-Jan-01 23:09

You stop it by overriding OnOK and OnCancel. You can make the buttons still work by checking the keystate with GetKeyState(VK_RETURN) (or VK_ESCAPE) and returning if they are down. Then your button works, but the key does not.

Christian

The content of this post is not necessarily the opinion of my yadda yadda yadda.

To understand recursion, we must first understand recursion.

Duplicate entries inside my std::map. Why?

Alvaro Mendez19-Jan-01 10:48

19-Jan-01 10:48

Hi,

I have structure that looks similar to this:

struct MyInfo
{
  CString m_str1;
  CString m_str2;
  COleDateTime m_dtm1;
  CString m_str3;
 
  MyInfo(const CString& str1, const CString& str2, const COleDateTime& dtm1, const CString& str3) : 
    m_str1(str1), m_str2(str2), m_dtm1(dtm1), m_str3(str3)
  { }
 
  bool operator<(const MyInfo& info)
  {
    return (m_str1 < info.m_str1 ||
            m_str2 < info.m_str2 ||
            m_dtm1 < info.m_dtm1 ||
            m_str3 < info.m_str3);
  }
};

I have a map of MyInfo to CString values, like this:

std::map< MyInfo, CString > mapInfo;

I insert/update elements into the map using operator[], like this:

void accumulate(const CString& str1, const CString& str2, const COleDateTime& dtm1, const CString& str3, const CString& strValue)
{ 
  mapInfo[MyInfo(str1, str2, dtm1, str3)] += strValue;
}

Notice that strValue is appended to whatever is already there.

Then later I iterate through every element in the map, but the problem is that I'm getting duplicate entries in the map (for the same MyInfo object). Why?

Thanks,
Alvaro

C^hris L^osinger19-Jan-01 11:35

C^hris L^osinger

19-Jan-01 11:35

...i just tried your code (with slight modifcations to make it compile) and it worked fine, no duplicate entries.

i even did two identical "accumulate" calls in a row, to try to duplicate keys. when i dumped the map, though, the keys were unique.

-c

Alvaro Mendez22-Jan-01 5:54

22-Jan-01 5:54

I really appreciate you looking into this problem for me Chris! Unfortunately I wasn't expecting to receive a "could not reproduce it" response otherwise I would have taken greater care to avoid it.

Here's how I was able to reproduce this problem. I took my sample code into a new MFC dialog based application I called "Doodle". I added a button to it and then a handler which I called OnButtonTryMap. Then inside I called the (global) accumulate function 100 times to insert/update the same MyInfo objects to the map each time. Here's how it looked:

#pragma warning (disable:4786)  // disables: identifier was truncated to '255' characters in the debug information
#include <map>

struct MyInfo
{  
	CString m_str1;  
	CString m_str2;  
	COleDateTime m_dtm1;  
	CString m_str3;   
	
	MyInfo(const CString& str1, const CString& str2, const COleDateTime& dtm1, const CString& str3) :     
		m_str1(str1), m_str2(str2), m_dtm1(dtm1), m_str3(str3)  
	{ }   
		
	bool operator<(const MyInfo& info) const  
	{    
		return (m_str1 < info.m_str1 ||            
				m_str2 < info.m_str2 ||            
				m_dtm1 < info.m_dtm1 ||            
				m_str3 < info.m_str3);  
	}
};
 
// Global objects (for testing purposes of course)
std::map< MyInfo, CString > g_mapInfo;
const COleDateTime g_dtmCurrent = COleDateTime::GetCurrentTime();
 
void accumulate(const CString& str1, const CString& str2, const COleDateTime& dtm1, const CString& str3, const CString& strValue)
{   
	g_mapInfo[MyInfo(str1, str2, dtm1, str3)] += strValue;
}
 
void CDoodleDlg::OnButtonTryMap() 
{
	CString str1, str2, str3;
	COleDateTime dtm = g_dtmCurrent;
 
	// Add the same 100 items each time this handler is called
	for (int iItem = 0; iItem < 100; iItem++)
	{
		str1.Format("str1 = %d", iItem);
		str2.Format("str2 = %d", iItem + 1);
		str3.Format("str3 = %d", iItem + 2);
		dtm += 1;

		accumulate(str1, str2, dtm, str3, str1);
	}
 
	// This should be 100 but...
	CString strMessage;
	strMessage.Format("There are %d items in the map.", g_mapInfo.size());
	AfxMessageBox(strMessage);
}

Try this and see if you get the same results. The first time I press the button I get "100 items" in the message. The second time, I get 118! The third time I get 142, then 154, and so on. If I've done this correctly, I should always see 100 items, shouldn't I? Confused | :confused:

Thanks for your help,
Alvaro

Alvaro Mendez22-Jan-01 8:16

22-Jan-01 8:16

You hit the nail on the head! It's the ambiguous comparison that's causing the problem. How could I have been so blind? I changed the less-than operator to this and now it works as expected:

bool operator<(const MyInfo& info) const  
{    
	return ((m_str1 < info.m_str1) ||
		(m_str1 == info.m_str1 && m_str2 < info.m_str2) ||
		(m_str1 == info.m_str1 && m_str2 == info.m_str2 && m_dtm1 < info.m_dtm1) ||
		(m_str1 == info.m_str1 && m_str2 == info.m_str2 && m_dtm1 == info.m_dtm1 && m_str3 < info.m_str3));
}

Thanks for your help!
Alvaro

C^hris L^osinger22-Jan-01 7:58

C^hris L^osinger

22-Jan-01 7:58

the problem is in your operator < function.

if MyInfo a = {"E", "A", xxx, xxx} MyInfo b = {"A", "E", xxx, xxx}

a will always be less than b; and b will always be less than a. but std::map requires that the comparison is strict. a < b or b < a, not both.

there's a good chance the ambiguous comparison is screwing with the map's tree.

-c

Alvaro Mendez22-Jan-01 7:10