C / C++ / MFC Discussion Boards

Christian Graus3-Dec-02 16:11

3-Dec-02 16:11

That's cool. Just forget you ever heard the name, OK ? :P

Christian

No offense, but I don't really want to encourage the creation of another VB developer. - Larry Antram 22 Oct 2002

Hey, at least Logo had, at it's inception, a mechanical turtle. VB has always lacked even that... - Shog9 04-09-2002

Again, you can screw up a C/C++ program just as easily as a VB program. OK, maybe not as easily, but it's certainly doable. - Jamie Nordmeyer - 15-Nov-2002

Re: Enum vs #define

Nick Parker3-Dec-02 16:45

Nick Parker

3-Dec-02 16:45

Christian Graus wrote:
Just forget you ever heard the name, OK ?

What name? Cool | :cool:

Nick Parker

Not everything that can be counted counts, and not everything that counts can be counted. - Albert Einstein

Re: Enum vs #define

Christian Graus3-Dec-02 16:47

Christian Graus

3-Dec-02 16:47

I was hoping you'd say that... :P

Christian

No offense, but I don't really want to encourage the creation of another VB developer. - Larry Antram 22 Oct 2002

Hey, at least Logo had, at it's inception, a mechanical turtle. VB has always lacked even that... - Shog9 04-09-2002

Again, you can screw up a C/C++ program just as easily as a VB program. OK, maybe not as easily, but it's certainly doable. - Jamie Nordmeyer - 15-Nov-2002

Re: Enum vs #define

Anonymous3-Dec-02 10:42

Anonymous

3-Dec-02 10:42

I avoid preprocessor where ever possible, as a general rule.

About defines... I personaly think enums are better b/c they do not polute global namespace. I put them into scope of my class and access them with CMyClass::VALUE1, CMyClass::VALUE2 (like in your exmaple).

Re: Enum vs #define

Anonymous3-Dec-02 10:45

Anonymous

3-Dec-02 10:45

"I avoid preprocessor where ever possible, as a general rule."

oh, I ment in C++...

with C this rule wouldn't be possible. But C++ introduced so many features which reduces use of preprocessor/precompiler to a vanishing minimum.

Re: Enum vs #define

Jörgen Sigvardsson3-Dec-02 11:58

Jörgen Sigvardsson

3-Dec-02 11:58

Enums are type safe which is a nice thing^tm. They are also recognized by the compiler and can be displayed using the symbolic name in debuggers which is also a nice thing^tm.

I use #define's sometimes though. But that's because all those countless hours of C-coding has affected my brain. Smile | :)

--
This space for rent.

Re: Enum vs #define

Brad Bruce3-Dec-02 13:00

Brad Bruce

3-Dec-02 13:00

Thank-you all for your comments. Now to convince about a half-dozen people to listen...

You've all had good arguments for enums.

Thanks
Brad

thread pool

gringo3-Dec-02 8:41

gringo

3-Dec-02 8:41

what is a thread pool?

Re: thread pool

valikac3-Dec-02 9:00

valikac

3-Dec-02 9:00

A thread pool is a collection of threads the programmers instantiates, but the operating system initialize and deallocate. In other words, the operating system does the cleanup. The programmers adds new threads to the pool and their callback functions.

Kuphryn

Re: thread pool

Daniel Turini3-Dec-02 9:22

Daniel Turini

3-Dec-02 9:22

When you start with multithread programming, soon you'll notice that the thread creation and setup and later destruction has a cost. This cost can be too much in a machine with a high utilization (e.g. a web server in a busy web site). So, a optimization algorithm is pre-creation of a number of threads and make them wait watching for "jobs" that need to be processed, and quickly returning to the "wait" state.

I see dumb people

creating .wav files

chrishall33-Dec-02 8:32

chrishall3

3-Dec-02 8:32

Hi all,
what I'm trying to do, and failing obviously, is to create .wav files from .raw files (plain text files, just full of integers).
the problem is that I dont know how to create the header for the wav file properly. I'm going to be creating the same type of wav file all the time, ie 16khz, mono, 8-bit unsigned.
What I'm doing so far is using the fstream function but I'm not sure how to calculate all the required information from the .raw file.
The only change will be the size of the file, so I think that a fairly generic header would do the job, with the only thing having to change being the samples.

Can anyone help me here, I've looked around but still lost.

Thanks in advance all,
Confused | :confused:

Chris

Re: creating .wav files

Selevercin3-Dec-02 11:44

Selevercin

3-Dec-02 11:44

This[^]has everything you will need, I think. Goes into a detailed header description, too.

Have fun and maybe use it to write an article Smile | :)

If you have a problem with my spelling, just remember that's not my fault. I (as well as everyone else who learned to spell after 1976) blame it on Robert A. Kolpek for U.S. Patent 4,136,395.

Injected code weirdness....VC 7

-=jarl=-3-Dec-02 8:28

-=jarl=-

3-Dec-02 8:28

I just had a look at the code injected by the compiler when using the __event, __hook and
__raise keywords on native C++ code. The sample in the help-files which come with VC 7.0
define a void-event like so;

__event void MyEvent( int value );

and __hook a reciever to it and subsequently __raise it.

Fine.

So I changed it to this;

__event int MyEvent( int value );

and looked at the generated code for the __raise, ( now returning an int ), which is like so;

<br />
 inline void  CSource::MyEvent(int i1) <br />
 {<br />
    __EventingCS.Lock();<br />
    __eventNode_CSource_MyEvent* node = __eventHandlerList_CSource_MyEvent;<br />
    <br />
    int hr = (int) 0;<br />
    for (; node != 0; node = node->next) <br />
    {<br />
        hr = node->__invoke(i1);<br />
	if ( hr!=0 )<br />
	{<br />
	   return hr;          //< BAD STUFF HAPPENS HERE<br />
	}<br />
    }<br />
    <br />
    __EventingCS.Unlock();<br />
    <br />
    return hr;<br />
 }<br />

( that comment is mine, not MS' Roll eyes | :rolleyes:

),

Is it just me or is this code broken ? The only way this code is not broken is
if there is some secret exception handling semantics going on which I don't know about.
If that's the case I stand corrected.

However, if it is not, then that piece of code will die somewhere bad due to a deadlock.

Anyone ?

cheers
-=jarl=-

----------------------------
jarl ostensen
Lead Technology Programmer
Bullfrog/Electronic Arts Inc.

check if two process exist and close the last opened and show the first

youssef3-Dec-02 8:21

youssef

3-Dec-02 8:21

Hi,

I execute my pgm two times .
I would like to know how can I do for inhibe the second pgm execution
I would like to show the first pgm and close the second pgm.

Best Regards

youssef

Re: check if two process exist and close the last opened and show the first

Paul M Watt3-Dec-02 9:02

Paul M Watt

3-Dec-02 9:02

Here is a very extensive article on what you want to do by Joseph M. Newcomer. Check it out.

Avoiding Multiple Instances of an Application[^]

Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!

Re: check if two process exist and close the last opened and show the first

valikac3-Dec-02 9:04

valikac

3-Dec-02 9:04

A member posted a simular question at CodeGuru. Here is the thread.

http://www.codeguru.com/forum/showthread.php?s=&threadid=221071

Kuphryn

wierd problems w/ vC++ , help ?! :)

joshfl3-Dec-02 7:25

joshfl

3-Dec-02 7:25

im having this strange problem with a program im developing.

The program compiles & links with 0 errors, and 0 warnings on both Debug, and Release Configurations.

The Problem is midway thru execution of the main function on my Release Compile , I get one of those mysterious MFC error dialog boxes (send / dont send to microsoft) that doesnt really tell me much about the problem....

the code that this error is contained in is .......(sorry , i know its a little hard to read this way, this text box takes out the formatting... )

/// here will start the directory iteration
for (int ji=0;ji<fia.GetSize();ji++) {

char *c1 = new char[100000];

//read into c1
FILE *input;
if ( (input = fopen( fia[ji].GetFilePath(), "r" ) ) == NULL )
{
AfxMessageBox( "Could not open file....\n" );
}
numread = fread( c1, sizeof( char ), 100000, input );
c1[++numread] = '\0';
fclose( input );

// call api function
if(NULL != dllHandle)
{
// If the function address is valid, call the api's function.
if (runTimeLinkSuccess = (NULL != BounceCheckPtr))
{
result = BounceCheckPtr(*c1, *c2, len, *c3, *c4);
}
}

///// prepare database entry
UCHAR szSqlStr[128];
if (result == 0) {
sprintf((char*)szSqlStr,"INSERT into bouncetest Values ('GB', '%s')",c2);
}
if (result == 1) {
sprintf((char*)szSqlStr,"INSERT into bouncetest Values ('HB', '%s')",c2);
}
if (result == 2) {
sprintf((char*)szSqlStr,"INSERT into bouncetest Values ('SB', '%s')",c2);
}
if (result == 3) {
sprintf((char*)szSqlStr,"INSERT into bouncetest Values ('GB', '%s')",c2);
}
if (result == 9) {
sprintf((char*)szSqlStr,"INSERT into bouncetest Values ('GB', '%s')",c2);
}

// set return code
int m_iIdentification_Code = result;

// Switch Structure
switch( m_iIdentification_Code )
{

case 1:
// Allocate memory for the statement handle
retcode = SQLAllocStmt (hDBC, &hStmt);
// Prepare the SQL statement by assigning it to the statement handle
retcode = SQLPrepare (hStmt, szSqlStr, sizeof (szSqlStr));
// Execute the SQL statement handle
retcode = SQLExecute (hStmt);
// Project only column 1 which is the models
SQLBindCol (hStmt, 1, SQL_C_CHAR, szModel, sizeof(szModel), &cbModel);
// Get row of data from the result set defined above in the statement
retcode = SQLFetch (hStmt);
// Free the allocated statement handle
SQLFreeStmt (hStmt, SQL_DROP);
break;

default:;

}

// delete memory i create on heap
delete[] c1;
}

it loops once, and then it dies on the second file read section...
any ideas / suggestions... would be appreciated Smile | :)

Re: wierd problems w/ vC++ , help ?! :)

-=jarl=-3-Dec-02 8:36

-=jarl=-

3-Dec-02 8:36

Just having a quick look; ye code looks a bit dodgy;

<br />
numread = fread( c1, sizeof( char ), 100000, input ); <br />
c1[++numread] = '\0';<br />

which can lead to

<br />
if numread==100000 )<br />
{<br />
 DoOverwritePseudoRandomMemory( '\0' );<br />
}<br />

in debug-build you would have some pad-bytes which might silently swallow this.

Don't know if this is the problem, but it certainly can be a problem. Smile | :)

-=jarl

----------------------------
jarl ostensen
Lead Technology Programmer
Bullfrog/Electronic Arts Inc.

Re: wierd problems w/ vC++ , help ?! :)

Christian Graus3-Dec-02 10:47

Christian Graus

3-Dec-02 10:47

jDawwg wrote:
char *c1 = new char[100000];

jDawwg wrote:
FILE *input;
if ( (input = fopen( fia[ji].GetFilePath(), "r" ) ) == NULL )

Why are you using C style file handling and fixed size buffers ? If you use iostreams and std::string, you can do this so much nicer, and without there being any risk of a buffer overrun or truncated read, nor would you allocate a huge buffer that you do not need.

jDawwg wrote:
retcode = SQLAllocStmt (hDBC, &hStmt);
// Prepare the SQL statement by assigning it to the statement handle
retcode = SQLPrepare (hStmt, szSqlStr, sizeof (szSqlStr));
// Execute the SQL statement handle
retcode = SQLExecute (hStmt);
// Project only column 1 which is the models
SQLBindCol (hStmt, 1, SQL_C_CHAR, szModel, sizeof(szModel), &cbModel);
// Get row of data from the result set defined above in the statement
retcode = SQLFetch (hStmt);
// Free the allocated statement handle
SQLFreeStmt (hStmt, SQL_DROP);

What is the point of grabbing the error status if you never check it ?

jDawwg wrote:
sprintf((char*)szSqlStr,"INSERT into bouncetest Values ('GB', '%s')",c2);

I think that &szSqlStr[0] is nicer syntax, but that's just me.

I reckon if you used C++ file handling and strings, your problem would probably go away.

Christian

No offense, but I don't really want to encourage the creation of another VB developer. - Larry Antram 22 Oct 2002

Hey, at least Logo had, at it's inception, a mechanical turtle. VB has always lacked even that... - Shog9 04-09-2002

Again, you can screw up a C/C++ program just as easily as a VB program. OK, maybe not as easily, but it's certainly doable. - Jamie Nordmeyer - 15-Nov-2002

Re: wierd problems w/ vC++ , help ?! :)

joshfl4-Dec-02 8:02

joshfl

4-Dec-02 8:02

Excellant ! thanks for the help Chris / Jarl! !
(jarl, thanks for the followup email too)

Im going to implement these suggestions and ill update you on how it goes.. Smile | :)

i appreciate all the tips on making my code better too, because Im not really a c++ expert (yet, im optimistic ). the current experience I do have w/C++ has been hacking together projects out of neccessity so im sure its sloppy....

Re: wierd problems w/ vC++ , help ?! :)

Christian Graus4-Dec-02 8:47

Christian Graus

4-Dec-02 8:47

jDawwg wrote:
appreciate all the tips on making my code better too, because Im not really a c++ expert (yet, im optimistic ).

So long as you maintain this attitude, you will end up being better than most. Good luck !!

Christian

No offense, but I don't really want to encourage the creation of another VB developer. - Larry Antram 22 Oct 2002

Hey, at least Logo had, at it's inception, a mechanical turtle. VB has always lacked even that... - Shog9 04-09-2002

Again, you can screw up a C/C++ program just as easily as a VB program. OK, maybe not as easily, but it's certainly doable. - Jamie Nordmeyer - 15-Nov-2002

How to change caption of Property Page

Alois Kraus3-Dec-02 6:57

Alois Kraus

3-Dec-02 6:57

Hello,

I want to change the caption of my Property Page at runtime.
SetWindowText does not the trick. The Caption Text specified
in the Dialog editor is always used, no change after a SetWindowText
call in OnInitDialog.

Any Idea ?

Re: How to change caption of Property Page

Navin3-Dec-02 7:30

Navin

3-Dec-02 7:30

Wow - deja vu, I am having the EXACT SAME PROBLEM. Although my scenario is a little different - my property page is in Wizard mode.

If you know the new title when the constructor of the property page is called, you can put this in the property page constructor:

<br />
m_psp.dwFlags |= PSP_USETITLE;<br />
m_psp.pszTitle = "Some New Title";<br />

BUT... this will NOT work after the property page has already been created! If anyone knows of a way to change the property page title (especailly in a wizard-mode property page) at run-time (NOT in the constructor) that actually works, I'm all ears.

I hate property sheets.. one of these days I'll write my own custom version of them and avoid all the silly restrictions they have.

Even a broken clock is right twice a day.

Yay, I figured it out!

Navin3-Dec-02 7:45

Navin

3-Dec-02 7:45

Check out this knowledge base item:

http://support.microsoft.com/default.aspx?scid=KB;en-us;q141487[^]

I was able to use the third method and it works. Woohoo!

Even a broken clock is right twice a day.

Re: Yay, I figured it out!

Alois Kraus4-Dec-02 0:58

Alois Kraus

4-Dec-02 0:58

Cool,

it works for me too.

Thanks

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.