C / C++ / MFC

12-Sep-05 8:57

Use ReadDirectoryChangesW() and/or FindFirstChangeNotification() so that you don't needlessly tie up the CPU.

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

lrand48 and srand48

RedDragon2k12-Sep-05 7:21

RedDragon2k

12-Sep-05 7:21

Hello,

I have found a code snippet on the internet which uses this both functions. The File includes the stdlib.h where this both functions should be defined. But they aren't.
Why aren't they defined ? Where can i download a stdlib.h file where they are defined ?

With best regards,
RedDragon2kx

David Crow12-Sep-05 7:27

12-Sep-05 7:27

Are you sure those functions, and the code snipet for that matter, are not targeted for a Unix platform? The Windows SDK has no such functions.

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

C^hris L^osinger12-Sep-05 7:43

C^hris L^osinger

12-Sep-05 7:43

a quick googling shows this to be a common definition:

#ifdef WIN32 
#define lrand48(x) rand(x) 
#define srand48(x) rand(x) 
#endif

Cleek | Image Toolkits | Thumbnail maker

-- modified at 13:44 Monday 12th September, 2005

David Crow12-Sep-05 9:04

12-Sep-05 9:04

Chris Losinger wrote:
#define srand48(x) rand(x)

I would think that srand48() would resolve to srand().

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

Re: limitation of edit box

C^hris L^osinger12-Sep-05 9:23

C^hris L^osinger

12-Sep-05 9:23

yep. probably.

Cleek | Image Toolkits | Thumbnail maker

limitation of edit box

SANJAY7612-Sep-05 7:12

SANJAY76

12-Sep-05 7:12

I need to display more than 5000 chars in a edit box.

It seems like MFC edit bos has a limit of 5000 chars.

any suggestions to get around this would be helpful.

thanks
Sanjay

David Crow12-Sep-05 7:22

Re: limitation of edit box

12-Sep-05 7:22

Sanjay R. Zore wrote:
It seems like MFC edit bos has a limit of 5000 chars.

No such limit exists. What makes you think that an edit control is limited to 5000 characters?

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

C^hris L^osinger12-Sep-05 9:22

C^hris L^osinger

12-Sep-05 9:22

see CEdit::LimitText

unless you're on 16-bit Windows or Win 95, the only limit on edit control data size is the size of an unsigned 32 bit integer, which is somewhat larger than 5000...

Cleek | Image Toolkits | Thumbnail maker

Threads

Eytukan12-Sep-05 4:50

12-Sep-05 4:50

i'm trying to run two separate threads. its working when i use an Integer to be passed as an argument to the thread. for example, if i send '1' one thread will keep on telling 1,1,1,1,1,1,1.

[tested using msgbox]

mean while, i send '2'. then another instance of the thread will start saying 2,2,2,2,2,2,

so u will get like 1,2,1,2,1,2,2,1,2,1,1.. like that.. its woking fine.

But if i pass a char[] parameter, its not working Frown | :(

ie,

if i pass "TEST",
it says , "TEST","TEST","TEST".......

meanwhile if i start another to say "CODE",

its destroys "TEST" and so two instance of "CODE" is displayed.
like instead of "TEST","CODE","TEST","CODE",... am getting like "CODE","CODE","CODE"...

plz tell me how to go..
thanks in advance

Thanks in advnace
V

John M. Drescher12-Sep-05 5:52

John M. Drescher

12-Sep-05 5:52

Vivekuniq wrote:
plz tell me how to go.

You need thread synchronization for this to work. Place a critical section or mutex around your display routine so that only one thread can print at one time.

John

Eytukan12-Sep-05 7:59

12-Sep-05 7:59

but how is it working for Integers?

V

John M. Drescher12-Sep-05 8:03

John M. Drescher

12-Sep-05 8:03

Without the code I can only guess... So here is my best guess: Because the code to output the integers takes so fast that there is no context switch between the call.

John

code

Eytukan12-Sep-05 8:15

12-Sep-05 8:15

if there is no context switch , it should print the same value right?.. sorry if i misunderstand, anyway plz view the code here.. plz try to help me . everytime i'm struggling with the threads Frown | :(

.

char[4] agIndv;

UINT CQACDDlg::DevMonitoring(LPVOID p)
{
CQACDDlg * me = (CQACDDlg *)p;
me->DevMonitoring(agIndv);
return 0;

}

void CQACDDlg::DevMonitoring(char[] ageID)
{
while(1)
{
AfxMessageBox(ageID);
//Sleep here for a while
}

}

void CQACDDlg::OnSetSplit() // onclick for new Threads
{
m_SplitID.GetWindowText(agIndv,5); //agIndv is global taken from a CEdit box
AfxBeginThread(DevMonitoring,this);

}

in the header file,
i declare
static UINT DevMonitoring(LPVOID lp);

V

David Crow12-Sep-05 6:25

12-Sep-05 6:25

The objects passed to the threads should probably be allocated on the heap rather than the stack, and then destroyed by the secondary thread. Something like (in MFC):

CString *strName = new CString("David");
AfxBeginThread(ThreadProc, strName);
...
UINT ThreadProc( LPVOID lpVoid )
{
    CString *str = (CString *) lpVoid;
    ...
    delete *str;
    return 0;
}

The same concept can be used with non-MFC code.

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

Eytukan12-Sep-05 8:10

12-Sep-05 8:10

can you tell me in context with the below code?
char[4] agIndv;

UINT CQACDDlg::DevMonitoring(LPVOID p)
{
CQACDDlg * me = (CQACDDlg *)p;
me->DevMonitoring(agIndv);
return 0;

}

void CQACDDlg::DevMonitoring(char ageID[])
{
while(1)
{
AfxMessageBox(ageID);
}

}

void CQACDDlg::OnSetSplit() // OnClick for new Threads
{
m_SplitID.GetWindowText(agIndv,5); //agIndv is global taken from a CEdit box
AfxBeginThread(DevMonitoring,this);

}

Thanks
V

Bob Stanneveld12-Sep-05 8:44

Bob Stanneveld

12-Sep-05 8:44

Hello,

If I see correct, you have a global instance of a char array. I guess that you use that array to write "TEST" and "CODE" to, that are passed to the thread.

Your problem is that you overwrite the contents of the array. So both threads are printing the same array!

To solve this problem, allocate a char array on the heap and pass that to the threads:

UINT CQACDDlg::DevMonitoring(LPVOID p)
{
    CQACDDlg * me = (CQACDDlg *)p;
    char* psAg = new char[/*length of string*/];
    // copy string contents to psAg
    me->DevMonitoring(psAg);
    return 0;
}

void CQACDDlg::DevMonitoring(char* pszAgeID)
{
    while(1)
        AfxMessageBox(ageID);
    delete[] pszAgeID;
}

Behind every great black man...
... is the police. - Conspiracy brother

Blog[^]

Eytukan12-Sep-05 22:20

12-Sep-05 22:20

Bob Stanneveld wrote:
Behind every great black man...
... is the police. - Conspiracy brother

Behind every great piece of code in this application is
......BOB and David- VivekUniq

EXCELLENT. thank u so much. Smile | :)

Bob Stanneveld13-Sep-05 1:25

Bob Stanneveld

13-Sep-05 1:25

Vivekuniq wrote:
EXCELLENT. thank u so much.

You're welcome Big Grin | :-D

Behind every great black man...
... is the police. - Conspiracy brother

Blog[^]

David Crow12-Sep-05 8:55

12-Sep-05 8:55

I'll try.

struct info
{
    CQACDDlg *pThis;
    char *string;
};
 
void CQACDDlg::DevMonitoring( LPSTR lp )
{
    while (1)
        AfxMessageBox(lp);
 
    delete [] lp;
}
 
UINT DevMonitoring( LPVOID lpVoid )
{
    struct info *me = (struct info *) lpVoid;
    me->pThis->DevMonitoring(me->string);
    delete me;
 
    return 0;
}
 
void CQACDDlg::OnSetSplit()
{
    struct info *s1 = new struct info;
    s1->pThis = this;
    s1->string = new char[5];
    lstrcpy(s1->string, "CODE");
    AfxBeginThread(::DevMonitoring, s1);
    
    struct info *s2 = new struct info;
    s2->pThis = this;
    s2->string = new char[5];
    lstrcpy(s2->string, "TEST");
    AfxBeginThread(::DevMonitoring, s2);
}

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

Eytukan12-Sep-05 22:27

delete always goes with set NULL?

12-Sep-05 22:27

Thank u so much man.. Smile | :)

.. i'm so happy Smile | :)

valerie9912-Sep-05 3:49

valerie99

12-Sep-05 3:49

Morning, all

Is it necessary to set the pointer to NULL after delete everytime in C++?
It would cause memory leak by just delete and NOT set to NULL, right?

Thank you!

Re: delete always goes with set NULL?

toxcct12-Sep-05 4:00

toxcct

12-Sep-05 4:00

valerie99 wrote:
Is it necessary to set the pointer to NULL after delete everytime in C++?

if you're about using the pointer variable again and want to be sure not to use an invalid memory block, yes, set to null.

valerie99 wrote:
it would cause memory leak by just delete and NOT set to NULL, right?

how ???? Unsure | :~

TOXCCT >>> GEII power
[toxcct][VisualCalc]

Re: delete always goes with set NULL?

David Crow12-Sep-05 4:28