C / C++ / MFC

Zizilamoroso22-May-02 0:08

Zizilamoroso

22-May-02 0:08

Could it be GlobalFreePtr? I don't find any docs about these macros on the msdn (tell something new Wink | ;)

).

[VISUAL STUDIO 6.0] [MFC] [WIN98/2]

Bluute tette! Dead | X|

moliate22-May-02 0:23

moliate

22-May-02 0:23

GlobalFreePtr

Note that if you use Win32 there is really no need to use this. The Win32 memory archetecture does not keep a separate global heap. LocalAlloc and GlobalAlloc are the same, and both malloc and new eventually calls a similar function called HeapAlloc.

/moliate

Two o'clock and walking through familiar London - Or what was familiar London before the cursor deleted certain certainties -
I watch a suit and tie man giving suck to the Psion Organizer lodged in his breast pocket
its serial interface like a cool mouth hunting his chest for sustenance, familiar feeling, and I'm watching my breath steam in the air.

Neil Gaiman - Cold Colours

Zizilamoroso22-May-02 0:53

Zizilamoroso

22-May-02 0:53

But is it harmless if you do use it?

[VISUAL STUDIO 6.0] [MFC] [WIN98/2]

Bluute tette! Dead | X|

moliate22-May-02 7:06

moliate

22-May-02 7:06

Yes, but it is only included for Win16 compability. It is a macro for allocating memory and locking the handle, which is not nessicary in Win32. Unlike Win16 memory allocation methods, Win32 methods have very few efficiency differences.

MSDN says that if you decide to use GlobalAllocPtr, GlobalFreePtr should be used to release the memory. This is probably just for backward compability, but better safe than sorry...

Cheers
/moliate

Neil Gaiman - Cold Colours

Debug vs Release version

21-May-02 22:44

It's really strange when your application works perfect under debug version, and later when you switch to Release it crashes. Here is how it happens.

1) I use CreateProcess to start a program and wait untill it ends.
CreateProcess of course crashes under Win2k/XP.
2) Then I switch to ShellExecute. Same thing happens.
3) I don't want to use WinExec!

So what's the difference between WinExec/ShellExecute/CreateProcess, and if you can provide some working code with theese functions

Regards,

Deian

Wolfram Steinke21-May-02 23:36

Wolfram Steinke

21-May-02 23:36

It is not surprising at all.

In dubug mode when you are using arrays or strings the compiler can reserve up to 16 bytes more that are actually needed. If you then write past the end of the memory and are still within that 'safe' area you will not have a problem. In release mode however even writing one byte past the end can cause a crash.

I would also take a careful look for memory and resource leaks some of which only cause an oject dump in debug mode but crash in release mode.

Happy programming!!

Alexandru Savescu22-May-02 0:13

Alexandru Savescu

22-May-02 0:13

Check out this article
It will not tell you what is going on withe CreateProcess and ShellExecute but it will give you an idea about the differences between Release mode and Debug mode

Best regards,
Alexandru Savescu

Jason Hooper22-May-02 0:54

Jason Hooper

22-May-02 0:54

Hi Deian,

Take a look at Surviving the Release Version.

Good luck!

- Jason
(SonorkID 100.611)

"I just recieved an email from myself but I didn't send it ?"
- Colin Davies, Sonork conference

How can I directly access image data in a CImgEdit-Control?

22-May-02 6:05

Thanks a lot guys, I really appreciate it Smile | :)

Greetings,

Deian

Ice-T.Polarbear21-May-02 22:39

Ice-T.Polarbear

21-May-02 22:39

Hi everyone!

I have to add an en-/decryption-algorithm into an (already existing) image processing application which uses the CImgEdit control by Kodak for displaying TIFF images. In order to implement the algorithm on the images I need direct access to the image data.

It would be easy to en-/decrypt the whole TIFF file. But due to reasons beyond my influence Wink | ;)

ONLY the image itself should be en-/decrypted, so that an encrypted TIFF file can be opened with any TIFF viewer but pixel-waste is all that is displayed... Cool | :cool:

Another point is, that I'm not allowed to write the decrypted image data onto disc but have to do any decryptions in memory solely.

Many thanx to anyone who can help me with this problem. Smile | :)

Best regards,
Andreas

P. S. I'm new at CodeProject and very hopeful someone will provide me the help I need Wink | ;)

Mutex?

21-May-02 22:36

Hello guys, I'm experiencing a strange behaviour in one of my programs. I use mutex to prevent two copies of my program running at the same time. Under win 9x/Me works fine, but under Win2k and XP don't. Any ideas why? Any advice, code sample or link appreciated

Prem Kumar21-May-02 22:40

Prem Kumar

21-May-02 22:40

Actually there should be no reason why it should not work.
You could post the code snippet, that would be more helpful
to see your problem

Deian21-May-02 22:48

Deian

21-May-02 22:48

Thanks for the reply Smile | :)

. I'm not currently at home, so I can't post the code today. But the method is the following:

declare a mutex, try to open it, if it's not there than this is the only copy -> create a mutex -> release it on exit, if the mutex is there, exit

jan larsen21-May-02 23:56

jan larsen

21-May-02 23:56

Hi Deian, i have no clue about your problem (too little information).
But it seems like your function is trying to do the same as CreateMutex which delivers a named mutex, if the object allready exists then you get that object, if not, the system creates a new object and that is the one you get.
CreateMutex is the function you should use to initialize a mutex, the description you gave is NOT threadsafe (another thread could create the mutex in between "try to open it, if it's not there than this is the only copy -> create a mutex").

"It could have been worse, it could have been ME!"