C / C++ / MFC

8-Sep-05 3:15

Hi folks,

I am working on an application that cross-links path names and keywords.
Currently I am using two maps that hold the information:

map<string, set<string> > m_path2keywords;
map<string, set<string> > m_keyword2paths;

While I am filling these maps with information they allocate much more memory than I expected (20.000 files -> more than 200MB of RAM). After minimizing and restoring the window that presents the data the allocated memory drops to less than 5MB!?!
I guess the previous waste of RAM is related to the map container.

So, would it be better to deal with one big map than to use two ?
How big is the organizational overhead of the map container ?
Are there any memory saving alternatives to the STL map container ?

Thanks in advance,
Achim Klein

We can do no great things, only small things with great love. - Mother Theresa

Niklas L8-Sep-05 3:42

8-Sep-05 3:42

The problem must reside in the layout of your data. What are those keywords and how many of those have you got for each path, on average? The overhead from the containers should be minimal, but the amount of (duplicate) data in there could be huge.

Achim Klein8-Sep-05 4:01

8-Sep-05 4:01

Hi Niklas,

thank you for your feedback.

What are those keywords
For example
Path = C:\My Files\Sun.jpg
Keywords:

sun
sky
light
bright
...

how many of those have you got for each path
Hard to say, but to give you a number, each path has about 10 keywords on average.

The problem must reside in the layout of your data.
Are there any more sophisticated ways to 'cross-link' data ?

Regards

We can do no great things, only small things with great love. - Mother Theresa

Niklas L8-Sep-05 3:58

8-Sep-05 3:58

...coming to think of it, this layout is really expensive. One solution would be to use four containers instead of two.

set<string> allMyKeyWords;<br />
set<string> allMyPaths;<br />
map< set<string>::iterator, set< set<string>::iterator > > m_path2keywords;<br />
map< set<string>::iterator, set< set<string>::iterator > > m_keyword2paths;<br />

Thus, in the maps you will only store iterators to the external sets (pointers to strings) rather then storing all strings hundreds (?) of times.

Niklas L8-Sep-05 4:01

8-Sep-05 4:01

Aargh, formating formating

set<string> allMyKeyWords;<br />
set<string> allMyPaths;<br />
map< set<string>::iterator, set< set<string>::iterator > > m_path2keywords;<br />
map< set<string>::iterator, set< set<string>::iterator > > m_keyword2paths;<br />

Achim Klein8-Sep-05 4:08

8-Sep-05 4:08

Yes, this is really an interesting alternative.

What happens if I delete any items from these two sets ?
Are the remaining iterators (that are stored in the maps) still valid ?

We can do no great things, only small things with great love. - Mother Theresa

Niklas L8-Sep-05 4:29

8-Sep-05 4:29

What happens if I delete any items from these two sets ?
Are the remaining iterators (that are stored in the maps) still valid ?

Nope. They are NOT. There are at least two ways to go here:

1. When removing let say a keyword, you will have to look up that entry in both maps (this is really not different from what you probably would have done with your original datastructure.) Removing items this way could be a lengthy operation on huge sets.

2. Depending on how you use the data, when removing a keyword, you could just set the actual keyword string to something that is invalid as a keyword, maybe an empty string? If you keep these structures as long as your app is running you will eventually get a lot of 'holes'. But the removal process is as fast as it could get, leaving (minor) performance penalties for other operations where you have to determine if an entry is valid or not. You could even run a clean-up pass to remove those holes whenever the app has nothing else to do.

Achim Klein8-Sep-05 5:43

function pointers and dlls

8-Sep-05 5:43

Sorry for the delay, I had visitors.
I think I can get along with 'holes' very well, so I'll try to realize the 'iterator solution'.

Thanks for your ideas.

Regards,
Achim Klein

We can do no great things, only small things with great love. - Mother Theresa

dave2k8-Sep-05 2:50

dave2k

8-Sep-05 2:50

hi guys.

i am trying to use pointers to functions in my dll to call a function in my .exe

i am storing my pointer in a global variable, so it can be called by any function.

the trouble is, i am finding that it can be only called by my addeventCallback function

i.e.
Code:
#include "dll.h"

EVENTCALLBACK evtcb = NULL;

BOOL WINAPI AddEventCallback(EVENTCALLBACK ptr) {
evtcb = ptr;
evtcb("pass on the message!");
evtcb("pass on the message!");
}

LRESULT CALLBACK GetMsgProc(int nCode, WPARAM wParam, LPARAM lParam) {
if(nCode < 0)
return CallNextHookEx(0, nCode, wParam, lParam);

evtcb("pass on the message!");

this displays "pass on the message" twicein the console, but when i try to cal evtcb() from GetMsgProc, it does not show again, meaning it has failed somewhere.

i know my GetMsgProc is fine as i have used other indicators such as MessageBepp(0) to show it is working.

what is the problem here?

cheers.

-- modified at 8:50 Thursday 8th September, 2005

About Wizard based project

parims8-Sep-05 1:53

parims

8-Sep-05 1:53

How to create a wizard based project .
Plz send me a simple application to create a wizard based program

Praveen Chowdam Kumar

Re: About Wizard based project

Cedric Moonen8-Sep-05 2:07

Cedric Moonen

8-Sep-05 2:07

Check that article[^]

Retrieve text from cursor position

Samik Karmakar8-Sep-05 1:47

Samik Karmakar

8-Sep-05 1:47

how can I retrieve the text from windows text editors using the keyboard cursor position

thank u

Re: Retrieve text from cursor position

Cedric Moonen8-Sep-05 2:08

Cedric Moonen

8-Sep-05 2:08

Samik Karmakar wrote:
windows text editors

What do you mean by that ? You mean Microsoft Word ? If yes you have to look for 'Word automation'. Otherwise be more specific.

Re: Retrieve text from cursor position

Samik Karmakar8-Sep-05 2:23

Samik Karmakar

8-Sep-05 2:23

i want to retrieve the text from any text editors notepad, wordpad.
i want to retrive the text when the cursor is over the letter.
example: say i have the word : text and my cursor is on 't'. so i want to retrieve 't' . now if i move the cursor from t to 'x' then i want to get 'x' retrieved say in a message box .

thank u

Re: Retrieve text from cursor position

David Crow8-Sep-05 2:44

David Crow

8-Sep-05 2:44

You'll need to use the EM_CHARFROMPOS message.

"One must learn from the bite of the fire to leave it alone." - Native American Proverb

Altering pattern for a brush

Niklas L8-Sep-05 1:21

How to play mp3 repeatedly

8-Sep-05 1:21

I have a pattern brush I would like to modify. The brush itself is to be used by windows internals.

My question is if it's at all possible to do something like

<br />
	LOGBRUSH lb;<br />
	::GetObject(hBrush, sizeof(LOGBRUSH), &lb);<br />
	hbm = (HBITMAP) lb.lbHatch;<br />
	::SelectObject(hdc, hbm);<br />

and the draw to the dc? If I already sent the hBrush to a win API function, will it be the very same I am trying to modify, or is windows using a copy of it (which means there's no point in doing the above)?

The win func is SetMenuInfo() but I doubt that matter.

Laffis8-Sep-05 1:15

Laffis

8-Sep-05 1:15

To play mp3, I use MCIWndPlay macro. I want to make the tune to be played repeatedly until user wants a stop. Does anyone know how to do it?

Ravi Bhavnani8-Sep-05 2:23

Ravi Bhavnani

8-Sep-05 2:23

You may need to use MCI_PLAY[^] with MCI_DGV_PLAY_REPEAT flag.

/ravi

My new year's resolution: 2048 x 1536
Home | Music | Articles | Freeware | Trips
ravib(at)ravib(dot)com

Laffis8-Sep-05 7:12

Laffis

8-Sep-05 7:12

(I am bing daft here - I have not much knowledge of mm programming.)

I wanted to use mci functions but hit a rock, because I do not know how to retrieve device id, and the device id is required to send the commands. Can you shed some light or point me to relevent sites? I tried but could not find any example telling me how to get the id, i.e. what name should I use in
MCIDEVICEID mciGetDeviceID(
LPCTSTR lpszDevice
);

I think once I know how to retrive the device Id I should be able to cook. PS I looked at the system.ini file, as a few internet findings suggest, but found nothing under the [mci] section.

Ravi Bhavnani8-Sep-05 7:21

Ravi Bhavnani

8-Sep-05 7:21

Assuming you know the name of the .mp3 file (I'm boldly assuming it's a file), you can simply do:

<code>// Start playing the file</code>
char szMp3File [MAX_PATH];
strcpy (szMp3File, "C:\\myFile.mp3");
VERIFY (::sndPlaySound (szMp3File, SND_LOOP | SND_ASYNC));

...

<code>// Stop playing the file</code>
VERIFY (::sndPlaySound (NULL, 0));

/ravi

My new year's resolution: 2048 x 1536
Home | Music | Articles | Freeware | Trips
ravib(at)ravib(dot)com

Laffis8-Sep-05 8:12

Laffis

8-Sep-05 8:12

I tried the sndPlaySound(...) and passed in a .mp3 file but the mp3 file did not get played. instead, a wav file was played. I guess it is because this func works only for wav file so a default sound was played rather than the mp3 specifed.

In fact before I use the mp3, I was playing a wav file instead, using the PlaySound(...), which is similar to this one you suggested. I thought I should move up the ladder a bit by tackling more advanced multimedia stuff, which means the application can be more flexible. This is the background info of how I got here...

Do u happed to know how to get device id? It is really nice to know.