Re: Running 10 threads at a time - C / C++ / MFC Discussion Boards

Tal S.1-Aug-07 22:37

1-Aug-07 22:37

Hello,

I have old VC6 compiled at VS2005.

I would like to keep 'Enable C++ Exceptions' = Yes (/EHsc) option at the project properties.

One of the functions: __event - is not compiled.

Do you know if I can use another function? Should I do any changes?

Thanks!

Re: Enable C++ Exceptions

Russell^'2-Aug-07 2:35

Russell^'

2-Aug-07 2:35

Are you not using the statement try-catch?
like:

try{
...
}catch(CMemoryException +pErr){
...
}

Russell

Running 10 threads at a time

neha.agarwal271-Aug-07 22:22

neha.agarwal27

1-Aug-07 22:22

Hi all,

I have made a for loop which has to execute 200 times. In that loop i have a started a worker thread. Now what i want is after 10 times that loop should wait for 1 of the thread to finish and then start next thread i.e only 10 thread can execute at a time.How to do it??

Thanks in advance

Re: Running 10 threads at a time

Iain Clarke, Warrior Programmer1-Aug-07 22:48

Iain Clarke, Warrior Programmer

1-Aug-07 22:48

I;d question your design decision as desiribed, but I'll assume your simplifying your actual problem.

Thread handles also act as signalling handles.

So:

....
    HANDLE hThread [MAX] = { NULL, NULL, ... NULL };
    DWORD dwID [MAX];

    for (nTest = 0; nTest < 10; nTest++)
    {
        hThread [nTest] = CreateThread (......., &(dwID [nTest], lParam);
        if (!hThread [nTest])
        {
            Handle error somehow
        }
    }

    for (nTest = 10; nTest < XXXXX; nTest++)
    {
        dwWait = WaitForMultipleObjects (hThread, 10, INFINITE);
        if (dwWait >= WAIT_OBJECT_0 && dwWait < WAIT_OBJECT_0+10)
        {
           nThread = dwWait - WAIT_OBJECT_0;
           hThread [dwThread] = CreateThread (......., &(dwID [nThread], lParam);
           if (!hThread [nTest])
           {
               Handle error somehow
           }
        }
    }

/pre>

Tada!

Iain.
<div class="CPhogPost"></div> 

<div class="ForumSig"></div>

Re: Running 10 threads at a time

Iain Clarke, Warrior Programmer1-Aug-07 22:52

Iain Clarke, Warrior Programmer

1-Aug-07 22:52

I would also point out that I have answered your question very literally. My answer would block your initial thread, is very fragile, etc.

Much better would be to look into thread pools (which I have no experience of), of have your thread posting a "I'm done!" message to a UI main thread, which would then fire off another thread. You could then give the user a more interactive experience, without thinking the process has hung. It would also allow you to handle failure more gracefully.

Iain.

Re: Running 10 threads at a time

Russell^'1-Aug-07 22:57

Russell^'

1-Aug-07 22:57

You can use a variable to count the threads

Global declaration:

<code>volatile </code>UINT RunningThread;   //Create the counter

The main function:

foo(){
RunningThread=0;   //Reset the counter
for(i=0;i<200;i++){
   if(RunningThread<10){
      //Create Thread
      RunningThread++;   //Incremente the counter
   }else{
      wait(100);
      i--;
      continue;
   }
}
}

The thread:

Thread(...){
//Work process
RunningThread--;  // Before it ends decrement the counter
}

Russell

Re: Running 10 threads at a time

neha.agarwal272-Aug-07 2:09

neha.agarwal27

2-Aug-07 2:09

i tried Russell's procedure but its hanging my application and not solving my problem completely....in my thread i m finding out a particular website's html code so, because of so many threads trying to do it, many times it gives page cannot be displayed....how to solve it

Re: Running 10 threads at a time

Russell^'2-Aug-07 2:27

Russell^'

2-Aug-07 2:27

Probally you have to use a semaphore to use the connection in a more efficient way, limiting the simultaneus request to the web.
You can use for example a boolean variable (like BOOL ConnectionIsBusy). If a thread find it TRUE then it waits that it becomes FALSE, then it lock itself the flag to TRUE, talk with the web, and at the end restore the flag value to FALSE.

A similar way is to limit the number of simultaneus connections using a variable like UINT ConnectionsNumber, that you could use to check that the connection opened are less of a particular value (i.e. 2 or 4).

But the problem depends also on the speed of your connection and/or the amount of traffic that you need to exchange with the web. You have to do some tests.

Russell

Re: Running 10 threads at a time

Mark Salsbery2-Aug-07 8:31

Mark Salsbery

2-Aug-07 8:31

Another way to implement Russell's suggestion is to use an I/O Completion Port[^]

This essentially combines a thread pool with a semaphore. With an I/O Completion Port you could
easily create a pool of 10 threads and queue up 200 operations to be executed by the threads as
they become available.

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

WM_INITDIALOG in VS 2005

vipin_nvk1-Aug-07 22:20

vipin_nvk

1-Aug-07 22:20

Hello

I am VS 2005 for the first time. I have selected a Dialog based application which uses MFC and I want to add a WM_INITDIALOG message handler. We use "Ctrl + W" for VC 6 to invoke class wizard and add a message handler for WM_INITDIALOG.

But in VS 2005, I selected properties of the dialog and looked under the "Messages" tab and dint find the WM_INITDIALOG message to add a handler for that. Do should I do this in VS 2005 ?

Thanx

Re: WM_INITDIALOG in VS 2005

Anurag Gandhi1-Aug-07 22:51

Anurag Gandhi

1-Aug-07 22:51

Add a class for the dialog if not added.

Go to Class view, Right click that class, go to property, then you will find all the virtual functions in the 3rd tab.

Anurag Gandhi.
http://www.softgandhi.co.nr

Re: WM_INITDIALOG in VS 2005

KarstenK1-Aug-07 23:49

KarstenK

1-Aug-07 23:49

I still miss the Class wizzard with its "Ctrl+W" feature. Cry | :((

IMHO this is a sign how carefully sometimes the job is done in the big M$-code machine Confused | :confused:

Greetings from Germany

How can i get Partition name from partition number?

Banks K1-Aug-07 22:03

Banks K

1-Aug-07 22:03

Hello All,

i have to find Partition name like(New Volume(K Smile | :)

) but by using partition number because i am having PARTITION_INFORMATION structure in the project.

now i am unable to get PArtition Name by using Partition Number.

if you have any idea about this please please share with me.

thanks
bankey

Re: How can i get Partition name from partition number?

Naveen1-Aug-07 23:48

Naveen

1-Aug-07 23:48

the volume name can be found out from the from GetVolumeInformation(). This function requires the drive letter not the partion number.If you manage to get the drive letter, you can get the volume name.

If there is no staright way for doing this, you can use the below method.

You can use the QueryDosDevice() function to find the diive letter from parition name. for eg consider the below code. If 'c' is the first partion, the tcDeviceName will contain \Device\HarddiskVolume1. and if you give 'd:', it will be \Device\HarddiskVolume2 and so on
TCHAR tcDeviceName[50];
QueryDosDevice( _T("C:"), tcDeviceName, 50 );

suppose you got 1 in the PARTITION_INFORMATION. then make string like "\Device\HarddiskVolume1". Now starting from A to Z, put a loop and call the QueryDosDevice. Compare the device name with the "\Device\HarddiskVolume1". If it matches, you have the drive letter.

nave

[OpenedFileFinder]

Interrupts in windows

zon_cpp1-Aug-07 21:35

zon_cpp

1-Aug-07 21:35

Hello there!
i work in VC++ and i want to write an asm code in my code
in this code, i want to write an interrupt,
i don't know list of interrupts in windows system???

I'd like to know how I can find the IDT addresses?
how do i access to this address (IDT) and how do i change address of an interrupt? (whit assembly code)

Zo.Naderi-Iran

Re: Interrupts in windows

Hamid_RT1-Aug-07 21:40

Hamid_RT

1-Aug-07 21:40

zon_cpp wrote:
list of interrupts in windows system

See here[^] does helpful?

WhiteSky

how can i control the sound of left and right speaker

rajneshmalik1-Aug-07 21:11

rajneshmalik

1-Aug-07 21:11

hi
how can i control the sound of left and right speaker by vc++/mfc.Actually i want to send different sound at same time on left and right speaker.

if anybody reply me i will obliged

malik

Re: how can i control the sound of left and right speaker

Hamid_RT1-Aug-07 21:37

Hamid_RT

1-Aug-07 21:37

See MIXERCONTROLDETAILS does your answer?

WhiteSky

Avoid using .ini files

vipin_nvk1-Aug-07 20:56

vipin_nvk

1-Aug-07 20:56

Hello

In my current project, I am using an .ini file to store information related to the application, such as windows start up position, critical information, file paths etc. This .ini file will be easily readable and editable.

Is there a way other than .ini file and "registry" where in the applicaiton information can be stored and used in between applicaiton sesstions.

Thanx

Re: Avoid using .ini files

Peter Weyzen1-Aug-07 21:03

Peter Weyzen

1-Aug-07 21:03

You can dream up your own file format and manage your settings files yourself. If you do so, make sure to put the files in the %APPDATA% folder.

The registry isn't that glamorous, but it's easy to use, it's secure, and it works.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<br />
Peter Weyzen<br />
Staff Engineer<br />
<A HREF="http://www.soonr.com">SoonR Inc -- PC Power delivered to your phone</A>

Re: Avoid using .ini files

CPallini1-Aug-07 21:06

CPallini

1-Aug-07 21:06

vipin_nvk wrote:
Is there a way other than .ini file and "registry" where in the applicaiton information can be stored and used in between applicaiton sesstions.

An XML file, for instance.

If you're using MFC, and you application is truly OO, then have a look at MFC Serialization http://msdn2.microsoft.com/en-us/library/6bz744w8(VS.80).aspx[^], a quite powerful tecnique.

Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Re: Avoid using .ini files

Hamid_RT1-Aug-07 21:23

Hamid_RT

1-Aug-07 21:23

See this[^] thread.

WhiteSky

Re: Avoid using .ini files

toxcct1-Aug-07 22:15

toxcct

1-Aug-07 22:15

why do you care the files are readable ? if the users modify it, it's their problem, not yours

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Re: Avoid using .ini files

mandanani1-Aug-07 22:23

mandanani

1-Aug-07 22:23

The purpose of .ini file is to facilitate the user to change environment settings, with out rebuilding the application.
I don't understand what security threat you will have until and unless some passwords are present in .ini file. Anyways password can also be encripted and stored in .ini file.

Re: Avoid using .ini files

toxcct1-Aug-07 22:26

toxcct

1-Aug-07 22:26

i'm not the OP... are you sure you wanted to say that to me ? Poke tongue | ;-P

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