C / C++ / MFC

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Re: Use of extern Xzyx987X28-Jun-04 23:01 Xzyx987X 28-Jun-04 23:01  You only need externs in files where the global variables aren't already defined. Just keep that in mind and you shouldn't have any problems. Re: Use of extern sweep12328-Jun-04 23:22 sweep123 28-Jun-04 23:22  st to re-cap the following are both OK? extern int g_nMyInt = 3; extern CMyType g_Mystruct1; // Initialised by a routine at start-up extern bool g_bMyFlag = true; Main() and int g_nMyInt = 3; CMyType g_Mystruct1; // Initialised by a routine at start-up bool g_bMyFlag = true; Main() -------------------------------------------------------- and use in other units as required:- extern int g_nMyInt; extern CMyType g_Mystruct1; // Initialised by a routine at start-up extern bool g_bMyFlag; Many thanks. Simple questions are sometimes not simple Re: Use of extern Rick York29-Jun-04 6:16 Rick York 29-Jun-04 6:16  You can't initialize an "extern" variable as you are in the first set. Otherwise, those are OK. __________________________________________ a two cent stamp short of going postal. Re: Use of extern Johnny ²29-Jun-04 4:48 Johnny ² 29-Jun-04 4:48  There is no guarantee that any variable, whether global or local, is initialised to 0. In a debug build, using VisualStudio, they do get initialised to 0, but that doesnt apply in a release build. AnimateWindow() Question User 58385228-Jun-04 21:37 User 583852 28-Jun-04 21:37  Hello Does anyone know of a way to use AnimateWindow() to fade out a window without blocking at all. If I use the sugested param of 200 ms my application feels unresponsive as the main thread is blocked. The documentation says I cannot call this on a window owned by another thread so I cant spawn off a thread to do it Setting up Visual C++ .NET to break on a windows error Xzyx987X28-Jun-04 20:48 Xzyx987X 28-Jun-04 20:48  I'm experiencing a very weird bug that I can't determine the source of. My only clue are some windows errors which shouldn't be occuring. And I don't just mean I think everything is set up so they shouldn't be occuring, I mean that between when I call SetLastError(0) and GetLastError() I'm not even calling any code that is capable of triggering them. The only explanation I could think of is that my program is somehow corrupting itself, but I've looked through my code carefully and I don't see how. Plus, the VC++ debugger isn't reporting and out of bounds memory access, buffer overuns, or anything else for that matter. I'd like to know if it's possible to set up VC++ to break on a windows error so I can find out excactly where the errors are coming from and why, without having to put a GetLastError() between every line of code. Way to Prevent memeory leak? nachilau28-Jun-04 20:29 nachilau 28-Jun-04 20:29  Hello all, I have a question on about how to prevent to prevent the memory leak? I am writing a window program, and I have an Assert() so that if any fatal erorr occured, the Assert() will call Sleep(INFIITE) to stop the program, and print out the error message to the user. By doing that, the only way to exit the program after Assert() has been called is to close the window. However, it causes a problem which is that even though the desturctor of each classes in the program will be called when the user close the window, there may still some memory leak in the local scoop when I use Assert() like this, eg in funciton f() f() { char* name = new char[10]; Assert(AnyError(), "Fatal Error!"); strcpy(name, "Hello"); delete [] name; } For example, if I get the Assert() if I get any error in f(), then when the user close the window, I will have a memory leak for 10 bytes. What is the best way to solve the problem? I don't want to use the try and catch block since the code will be mess up with all those try and catch block. And I really want to stop the program when the fatal error occurs. Any ideas? Thanks! Nacho Re: Way to Prevent memeory leak? User 58385228-Jun-04 20:43 User 583852 28-Jun-04 20:43  Im not sure i fully understand. If you program has hit a fatal error and is exiting then you could probably not worry and rely on the OS to clean up after you. Perhaps you could use a smart pointer A smart pointer is usually a template class that pretends to be a pointer by providing the -> and * operators. Because the smart pointer itself is on the stack its destructor will be called and you can delete the memory then. I think the stl has a smart ptr template. You might want to start there However if your Assert() function never returns then that wont work either. Why dont you throw an exception in your Assert() function and catch it at a higher level Good luck Re: Way to Prevent memeory leak? nachilau28-Jun-04 21:09 nachilau 28-Jun-04 21:09  Thanks for your suggestion. I know the way the smart pointer works, but as what you said, since the Assert function never return, smart pointer is no use in this case. Also, if I throw an exception, then, the try and catch block will go around in my code. That is so messy then! But thanks for your comment!! Re: Way to Prevent memeory leak? User 58385228-Jun-04 21:34 User 583852 28-Jun-04 21:34  As you are trying to deal with a rather general error could you not catch the exception once at a higher level? In your main() for example. If you are writing an MFC app im sure you could override CWinApp::Run() and put your try..catch in there. Re: Way to Prevent memeory leak? wb28-Jun-04 21:42 wb 28-Jun-04 21:42  if you run on something else than Win 3.11 the OS cleans up after you... Re: Way to Prevent memeory leak? nachilau28-Jun-04 21:51 nachilau 28-Jun-04 21:51  Thanks! But do you know how the OS clean is up for me? You mean the OS will keep doing a background search for the memory leak? Am I right? Thanks! Re: Way to Prevent memeory leak? wb28-Jun-04 22:05 wb 28-Jun-04 22:05  the OS has a table with all the memory you alocated, and when your program exits , the OS throws away that table and the Memory is free for other programs... Serial Communication in WIN CE Chinnaa Ganesh Kumar28-Jun-04 20:07 Chinnaa Ganesh Kumar 28-Jun-04 20:07  Hi, I am in the development of implementing the read/write operation in the WIN CE environment through COM Port I used the following code ... //============================================================== gCommHandle = CreateFile(L"COM1:", GENERIC_READ|GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL); bWrite = WriteFile(gCommHandle, "Test Msg", 8, &dwWrite, NULL); //============================================================== I could able to get the gCommHandle and the Writefile function also return TRUE after execution But nothing is getting written in the COM Port...(I observed this by the serial port monitoring tool) How can we perform read/write operation in COM port in WIN CE OS. Can some one help me in this regard. Thanks in advance, ~Chinna Hard Work Never Fails std::queue and Managed class Vadim Tabakman28-Jun-04 19:54 Vadim Tabakman 28-Jun-04 19:54  Hi all, I'm trying to do the following : std::queue <MyManagedClass *> m_qSomeName; but I get the following compile error ...\Vc7\include\deque(59): error C2847: cannot apply sizeof to managed type 'TestApp1::MyManagedClass' ok.. so I changed MyManagedClass to a non Managed Class, and now I get a different compile error: ...\TestApp1\MyServer.h(29): error C3633: cannot define 'm_qSomeName' as a member of managed 'TestApp1::MyServer' Now I'm just trying things out, but is it not possible to use the std::queue template class in managed c++? what about other STL classes? <EDIT> Before anyone says, why aren't you using .NET queue/list classes. I'm geniunely curious why I am not able to use STL </EDIT> Thanx Re: std::queue and Managed class Nemanja Trifunovic29-Jun-04 7:23 Nemanja Trifunovic 29-Jun-04 7:23  Making Managed C++ STL friendly.[^] Re: std::queue and Managed class Vadim Tabakman29-Jun-04 13:36 Vadim Tabakman 29-Jun-04 13:36  outstanding!! thanx very much Nemanja. Reading through your article and its great. giving it a big 5.. too bad there isn't a 6 If there's one thing I've learned, it's that life is one crushing defeat after another until you just wish Flanders was dead. - Homer Simpson Question on prefix and post fix rohit.dhamija28-Jun-04 19:49 rohit.dhamija 28-Jun-04 19:49  Dear All, I have a query on following case.Can some body tell the solution for the following: y = 5++++6*3; The answer turns out to be -12 when checked with a C compiler Also, i tried the same on borland delphi 5 and got the answer as 24 How is the processing going on in the above case. Thanks, Regards, Rohit Re: Question on prefix and post fix PJ Arends28-Jun-04 19:57 PJ Arends 28-Jun-04 19:57  Rohit Divas wrote: y = 5++++6*3; I would think code that would not even compile. No wonder it is giving you indeterminate results. "You're obviously a superstar." - Christian Graus about me - 12 Feb '03 "Obviously ???  You're definitely a superstar!!!" mYkel - 21 Jun '04 Within you lies the power for good - Use it! Re: Question on prefix and post fix Ian Darling29-Jun-04 2:57 Ian Darling 29-Jun-04 2:57  PJ Arends wrote: I would think code that would not even compile. I agree - it shouldn't - there's a missing operation between the 5++ and the ++6. I suspect someone's posted incorrect code, with a missing or extraneous '+' along the way. Either way, the C++ standard makes no specific guarantees about the order that statement is executed in - a set of operations can be performed in any order if they are within the same sequence point and the rules of precedence don't kick in, IIRC. So we're probably looking at undefined behaviour, hence the different results (watch out for those nasal demons ) Ian Darling The world is a thing of utter inordinate complexity ... that such complexity can arise ... out of such simplicity ... is the most fabulous extraordinary idea ... once you get some kind of inkling of how that might have happened - it's just wonderful ... the opportunity to spend 70 or 80 years of your life in such a universe is time well spent as far as I am concerned - Douglas Adams Re: Question on prefix and post fix Vadim Tabakman28-Jun-04 19:58 Vadim Tabakman 28-Jun-04 19:58  I tried to compile that in some code, and didn't succeed at all. it didn't like the ++ after the 5. I believe it expects a variable. so i'm not sure how you got that to compile why are you doing ++++ anyway? Re: Question on prefix and post fix rohit.dhamija28-Jun-04 20:14 rohit.dhamija 28-Jun-04 20:14  yes i did the same and it complied successfully on borland delphi 5 compiler, rohit Re: Question on prefix and post fix Vadim Tabakman28-Jun-04 20:28 Vadim Tabakman 28-Jun-04 20:28  but you said you got -12 when compiled with the C-compiler. It doesn't even look like valid C-code. If there's one thing I've learned, it's that life is one crushing defeat after another until you just wish Flanders was dead. - Homer Simpson SOAP 3.0 Question NeoHobbit28-Jun-04 19:28 NeoHobbit 28-Jun-04 19:28  I set up a HTTPConnector object like so: ISoapConnectorPtr Connector; Connector.CreateInstance(__uuidof(HttpConnector30)); Connector->Property["EndPointURL"] = "http://<someaddress>/soap/upload.aspx"; And it sets the Content-Type do application/dime in the HTTP Header. I require it to be multipart/form-data. No big complaint I thought so added this line: Connector->Property["RequestHTTPHeader"] = "Content-Type: multipart/form-data"; But instead of changing the current Content-Type it added a new line. ie: Content-Type: application/dime Content-Type: multipart/form-data What I need to know, is how to change the Content-Type in the HTTP Header. Thankyou Zoom In and Zoom Out aparajita28-Jun-04 19:28 aparajita 28-Jun-04 19:28  How to zoom in and zoom out a part of the image in VC++? Pls help... Aparna

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