C / C++ / MFC

30-Jun-05 23:31

Hello,

I just got back from my holliday, so this post may be a little late, but I didn't have internet access at my location Blush | :O

.

I agree that some problems are more easy to detect in a lower level context than others, but there is also a plethora of other problems that are more easy to detect with a high level view. An example of this is the infamous corner case bug, where you loop once too many or once to few. This is more easy to detect if you understand the context. (It's actually the comment that does the trick, but the high level view is less cluttered..)

I'll stop with my arguments, since I think that we both don't want to get involved in an endless debate about peoples passion for things.

Toby Opferman wrote:
It works under the same principal that if you wanted to crack a third party application, you don't need to know what that application's logic is you just need to find that one instruction that determines the path divergence to either fail or continue execution of the application.

It's mandatory to think that way, since you'll never have the source code available. If you have it, there would be no need to crack it.. Smile | :)

Toby Opferman wrote:
I wouldn't say you're below average. For example, you had the right idea on that keyboard input thread yesterd

ay about keeping track of the key presses, other people seemed to miss that on the thread.

Thank you, I feel flattered Blush | :O

Toby Opferman wrote:
There's a lot to learn and what you know today is usually only good for a few years before it's replaced by something new that you have to re-learn! Creating an ISR to keep track of key presses is definately not used by application programs anymore for example, yet I did that 10 years ago.

The coding techniques are generally old at the moment that you are using them. They are new at the moment you learn them. The key is to learn an abstract technique, algorithm, etc. that you can implement in different languages, so that you don't have to relearn everything. The only thing to relearn is the technique to implement the idea.

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

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Re: OT

Toby Opferman1-Jul-05 9:00

Toby Opferman

1-Jul-05 9:00

Bob Stanneveld wrote:
An example of this is the infamous corner case bug, where you loop once too many or once to few. This is more easy to detect if you understand the context. (It's actually the comment that does the trick, but the high level view is less cluttered..)

I've never had to go to source level debugging and I fix 10x as many bugs as anyone else. I was so good they only had be debugging everyone's code! So, I had to get momentum to move onto a different team (I work in research now) in order to avoid having to fix everyone's code for life. After years of debugging user mode traps, blue screens, etc. I've actually found patterns in debugging and use this to find the answer to the next bugs. I should write a book on "Debugging Patterns", how to recognize what a bug is by it's symptoms and how to fix it. I actually came up with an idea to completely automate debugging and cut down the work by a significant effort (Weeks worth of effort). Most of what you do is routine anyway.

I believe that high level code is more cluttered. Each line is a complex operation and if you attempt to comprehend it you will slow down.

Bob Stanneveld wrote:
I'll stop with my arguments, since I think that we both don't want to get involved in an endless debate about peoples passion for things.

Yes that's true, it becomes like OS wars or editor wars, it never ends!

Bob Stanneveld wrote:
It's mandatory to think that way, since you'll never have the source code available. If you have it, there would be no need to crack it..

I've found that this mentality actually works for everything and finds things faster. The source is always available for referencing if need be.

8bc7c0ec02c0e404c0cc0680f7018827ebee

JWood22-Jun-05 10:17

JWood

22-Jun-05 10:17

STL is an all or nothing proposition though - if you start using it, it triggers some changes in the way that the code is compiled and forces everything to STL. If you are dealing with legacy code this can be a major major - and unnecessary - pain in the neck.

Bob Stanneveld22-Jun-05 7:02

22-Jun-05 7:02

Hello,

May I suggest that you format your post, so that your for /* or other loop */ statement becomes visible.

May I ask why you use so much ugly C functions and buffers and copy all those things manually? You would write much cleaner code if you utilize all that the STL's streams or MFC's CString and CArray classes have to offer..

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

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tomek1823-Jun-05 2:06

tomek18

23-Jun-05 2:06

The reason I use such ugly code, is because that's the only code I know. I am a begginer in programming. At the moment I am reading some materials on STL and MFC, but find it quite difficult to understand, as I have a lot of gaps in my programming knowledge. To that I have no one to ask for help apart from the forum. So THANK YOU all for helping me out! Big Grin | :-D

Maybe you could help me out with this error I get:

cannot convert parameter 1 from 'unsigned short' to 'char *'
Conversion from integral type to pointer type requires reinterpret_cast, C-style cast or function-style cast.

The solutions you helped me out with, was not exaclty what I was looking for. Basicaly pszData is only 1 character at a time. So I want to store that 1 character in an array, then add the next character that comes from pszData and add it to the array. When I have 10 characters, That's when I want to display on screen. pszData recieves a character at different times, could be a split second or a whole day.

Thanks in Advance!

Bob Stanneveld23-Jun-05 2:29

23-Jun-05 2:29

tomek18 wrote:
The reason I use such ugly code, is because that's the only code I know. I am a begginer in programming. At the moment I am reading some materials on STL and MFC, but find it quite difficult to understand, as I have a lot of gaps in my programming knowledge.

Only time and practice will learn. We were all beginners once, and we are glad to help a fellow programmer!

tomek18 wrote:
cannot convert parameter 1 from 'unsigned short' to 'char *'
Conversion from integral type to pointer type requires reinterpret_cast, C-style cast or function-style cast.

Can you post the code? It's much easier for us to understand your problem if we see some code. If we see it, we can tackle the problem much faster.

tomek18 wrote:
The solutions you helped me out with, was not exaclty what I was looking for. Basicaly pszData is only 1 character at a time. So I want to store that 1 character in an array, then add the next character that comes from pszData and add it to the array. When I have 10 characters, That's when I want to display on screen. pszData recieves a character at different times, could be a split second or a whole day.

If you only need to wait for 10 characters, why are you using so large buffers? You don't even need to do all the copying! Try the following code:

// Add the following line in your view dialog class
// It is a string stream, that can be used to get data from and to store data in
// just like any other C++ stream (cout, cin, etc..)
std::stringstream m_sstrDataBuffer;

void CChildView::SortData(LPCTSTR pszData)
{
    // store the data in the buffer
    m_sstrDataBuffer << pszData;

    // see if the number of characters stored is 10 or more
    if( m_sstrDataBuffer.str().length() >= 10 )
    {
        // output the string and reset the buffer
        DisplayData(m_sstrDataBuffer.str().c_str());
        m_sstrDataBuffer.str(""); // reset
    }
}

Hope this helps! Smile | :)

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

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tomek1823-Jun-05 4:01

tomek18

23-Jun-05 4:01

Bob Stanneveld wrote:
Can you post the code? It's much easier for us to understand your problem if we see some code. If we see it, we can tackle the problem much faster.

I would if it just wasn't that long. I got the source code from this web site. if your interested http://www.codeproject.com/system/serial.asp

Basicaly the program just reads a character through the serial COM port, then passes that character to pszData. What I want to do, is to store all the single characters that come in, and after 80 have been recieved I want to sort out the data, and only send about 10 characters to the Display.

At the moment I am having problems converting Data types. Pointers, Strins, LPCTST, etc... I don't understand them much. And everytime I try a method I get an error saying something like: cant convert pointer to string vice versa.

Please Help me Confused | :confused:

Bob Stanneveld23-Jun-05 4:18

23-Jun-05 4:18

As long as a pointer doesn't point to a class, you can convert it from anything to anything. Unless you don't know what you are doing, you will get away with it.

The serial class that you are using is a good one. I use it too in one of my programs. So the problem is definitly not there.
Your problem however, is that you don't pass the number of bytes in the buffer (pszData) to your SortData function. You have that number, since the serial class demands a buffer size for the read actions. I suggest that you use those values to determine how much data is recieved.

tomek18 wrote:
At the moment I am having problems converting Data types. Pointers, Strins, LPCTST, etc... I don't understand them much. And everytime I try a method I get an error saying something like: cant convert pointer to string vice versa.

Use static_cast<PointerType>(OtherPointerType) for this purpose.

I think that you are a little bit over your head with this project if you have problems like this. I suggest that you do some more reading about data types, pointer arithmic and such. The basics should be enough to get the job done.

Good luck with it.

P.S.
If you have some problems with something, by all means, ask and post the source code too! Otherwise we will not be able to help you much...

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

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David Crow23-Jun-05 3:21

23-Jun-05 3:21

tomek18 wrote:
Basicaly pszData is only 1 character at a time.

While the compiler couldn't care less, and it certainly is not required, you might want to consider a different variable naming convention so that you and others who read your code can make better sense of it. See here.

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

what is MFCO42D.DLL?

liuyue22-Jun-05 5:44

liuyue

22-Jun-05 5:44

i debug my program, and the exception (unhandled exception in gis.exe(MFCO42D.DLL):0xc0000005 access violation.) arised when the instruction(mapinfo.CreateDispatch("MapInfo.Application"))run. how can i deal with it?

David Crow22-Jun-05 5:59

22-Jun-05 5:59

It is the debug version of the MFCOLE Shared Library.

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

liuyue22-Jun-05 14:29

liuyue

22-Jun-05 14:29

how can i deal with the problem?

David Crow23-Jun-05 3:14

23-Jun-05 3:14

Well, either mapinfo is not a valid COleDispatchDriver object, or "MapInfo.Application" is not a valid automation object identifier. I'd have to see more of your code to know for sure.

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

ThatsAlok22-Jun-05 18:22

ThatsAlok

22-Jun-05 18:22

liuyue wrote:
mapinfo.CreateDispatch("MapInfo.Application"))

Please Check that mapinfo variable hold valid reference to memory

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta

get logged on user

hph22-Jun-05 5:19

hph

22-Jun-05 5:19

hello,

i need to know who to determine whether a user is logged on or not. i have already tried GetUserName but this didn't work, because i have a service running as 'system', so GetUserName only returns 'system'. Now, how can i get this information ?

OS: Windows 2000

Thanks in advance.

Re: get logged on user

David Crow22-Jun-05 5:55

create check boxes on run time

22-Jun-05 5:55

Check out the UserName property of Win32_ComputerSystem.

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

Re: get logged on user

Toby Opferman22-Jun-05 9:12

Toby Opferman

22-Jun-05 9:12

If this is Windows 2000 and you think they will always launch the shell you could simpy enumerate processes looking for explorer.exe or whatever they replaced the shell with.

Alternatively you could write a Winlogon Notification DLL which gets notified of events such as Logon and Logoff.

8bc7c0ec02c0e404c0cc0680f7018827ebee

Re: get logged on user

hph22-Jun-05 22:24

hph

22-Jun-05 22:24

thanks for the hints, but i have found another workaround. because i have already a process which gets launched at startup - i simply put a pipe in it, which delivers the needed informationen whether a user has logged on.

thanks anyway.

softtec22-Jun-05 5:16

softtec

22-Jun-05 5:16

actually i want to open number of files at same time and at each time when ill click on "openfile" on "file" menu a check box would be created for each file. On each open file action check box would be created on group box next to previous one.
how can i do this?

David Crow22-Jun-05 5:19

22-Jun-05 5:19

softtec wrote:
how can i do this?

Do what? Open a number of files at the same time? Create a checkbox for each opened file? Add to a menu? What group box?

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

softtec22-Jun-05 5:28

softtec

22-Jun-05 5:28

actually i have created a menu
when i click openfile on File menu, a checkbox is created in groupbox right
but it works only when i open single file
as i click openfile menu i got assertion error
now i want whenever i click on open file menu,check box is created
and if i again click on open file menu another checkbox will be created just below the previuos one in the same groupbox.

David Crow22-Jun-05 5:39

22-Jun-05 5:39

softtec wrote:
a checkbox is created in groupbox right

What groupbox?

softtec wrote:
as i click openfile menu i got assertion error

What line of what file is asserting?

Are you using MFC?

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown