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  • Can I use memcpy in C++ to copy classes that have no pointers or virtual functions

    - by Shane MacLaughlin
    Say I have a class, something like the following; class MyClass { public: MyClass(); int a,b,c; double x,y,z; }; #define PageSize 1000000 MyClass Array1[PageSize],Array2[PageSize]; If my class has not pointers or virtual methods, is it safe to use the following? memcpy(Array1,Array2,PageSize*sizeof(MyClass)); The reason I ask, is that I'm dealing with very large collections of paged data, as decribed here, where performance is critical, and memcpy offers significant performance advantages over iterative assignment. I suspect it should be ok, as the 'this' pointer is an implicit parameter rather than anything stored, but are there any other hidden nasties I should be aware of?

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  • overflow technique in stack

    - by metashockwave
    int main(void) { problem2(); } void doit2(void) { int overflowme[16]; //overflowme[37] =0; } void problem2(void) { int x = 42; doit2(); printf("x is %d\n", x); printf("the address of x is 0x%x\n", &x); } Would someone help me understand why overflowme[37] =0; from the doit2 function will overwrite the value of x? (please include Program Counter and Frame Pointer of the function doit2 in your explanation) Thank you! It works every time with Project properties-Configuration properties-C/C++ -Code Generation-Basic Runtime Checks set to "Default". so it's not an undefined behavior.

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  • typedef resolution rule

    - by kumar_m_kiran
    Hi All, Can you Please tell me the resolution rule involved in resolving the meaning of the variable in a typedef. Any link related to the same will be very useful. Example #typedef string* pstring; const pstring parr; Here confusion arises whether const'ness is for pointer or the content. Now based on what thumb rule do can we start resolving the above interpretation of the pstring?. Smilarly, If I have a very complex typedef'ed variable, like #typedef void (func*)()(int), I should be able to resolve it using the thumb rule. Thanks in advance for your suggestions

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  • c++/cli pass (managed) delegate to unmanaged code

    - by Ron Klein
    How do I pass a function pointer from managed C++ (C++/CLI) to an unmanaged method? I read a few articles, like this one from MSDN, but it describes two different assemblies, while I want only one. Here is my code: 1) Header (MyInterop.ManagedCppLib.h): #pragma once using namespace System; namespace MyInterop { namespace ManagedCppLib { public ref class MyManagedClass { public: void DoSomething(); }; }} 2) CPP Code (MyInterop.ManagedCppLib.cpp) #include "stdafx.h" #include "MyInterop.ManagedCppLib.h" #pragma unmanaged void UnmanagedMethod(int a, int b, void (*sum)(const int)) { int result = a + b; sum(result); } #pragma managed void MyInterop::ManagedCppLib::MyManagedClass::DoSomething() { System::Console::WriteLine("hello from managed C++"); UnmanagedMethod(3, 7, /* ANY IDEA??? */); } I tried creating my managed delegate and then I tried to use Marshal::GetFunctionPointerForDelegate method, but I couldn't compile.

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  • Interpreter in C++: Function table storage problem

    - by sub
    In my interpreter I have built-in functions available in the language like print exit input, etc. These functions can obviously be accessed from inside the language. The interpreter then looks for the corresponding function with the right name in a vector and calls it via a pointer stored with its name. So I gather all these functions in files like io.cpp, string.cpp, arithmetic.cpp. But I have to add every function to the function list in the interpreter in order for it to be found. So in these function files I have things like: void print( arg ) { cout << arg.ToString; } I'd add this print function to the interpreter function list with: interpreter.AddFunc( "print", print ); But where should I call the interpreter.AddFunc? I can't just put it there below the print function as it has to be in a function according to the C++ syntax. Where and how should all the functions be added to the list?

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  • Boost singleton and undefined reference

    - by Ockonal
    Hello, I globally use singleton pattern in my project. To make it easier - boost::singleton. Current project uses Ogre3d library for rendering. Here is some class: class GraphicSystem : public singleton<GraphicSystem> { private: Ogre::RenderWindow *mWindow; public: Ogre::RenderWindow *getWindow() const { return mWindow; } }; In GraphicSystem constructor I fill the mWindow value: mWindow = mRoot->createRenderWindow(...); I cheked it, everything makes normally. So, now I have to use handler for the window in input system (to get window handle). Somewhere else in another class: Ogre::RenderWindow *temp = GraphicSystem::get_mutable_instance().getWindow(); GraphicSystem::get_mutable_instance().getWindow()->getCustomAttribute("WINDOW", &mWindowHandle); temp is 0x00, and there is segfault at last line (getting custon attribute). I can't understand, why does singleton returns undefined pointer for the window. All another singleton-based classes work well.

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  • What will be the setup process for website development?

    - by Vijay Shanker
    Hi, I want to create a simple site for my personal usage. And this only in python based technologies. So I want to get a expert oponian on this topic. What should i used as platform? I did a search for available options and found Django, grok, web2py and many more of these. Which one a novice use should use? If I choose to use only the basic python scripts then what option i have to work on? http://wiki.python.org/moin/WebBrowserProgramming. This link on python site confused me more, instead of solving my curiosity about the topic. Please give some pointer to accurate and easy to understand reading materials. I have got a idea of developing java based web applications using either spring-webmvc and struts. Can I relate Java process to python process for web development?

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  • Efficiently remove points with same slope

    - by Ram
    Hi, In one of mine applications I am dealing with graphics objects. I am using open source GPC library to clip/merge two shapes. To improve accuracy I am sampling (adding multiple points between two edges) existing shapes. But before displaying back the merged shape I need to remove all the points between two edges. But I am not able to find an efficient algorithm that will remove all points between two edges which has same slope with minimum CPU utilization. Currently all points are of type PointF Any pointer on this will be a great help.

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  • one document.createElement, append it twice, only shows once

    - by Sirber
    I have a button I want to use in the beginning and the end of the page: var button_save = document.createElement('button'); $("#compteurs").append(button_save); [...] $("#compteurs").append(button_save); but it only appear at the end of the page. If I remove it from the bottom of the page, it appear at the begining of page. It's a kind of pointer. Is there a way to create the button only once and use it twice? Thanks!

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  • How do IOS know which viewController is being viewed and hence need viewWillAppear to be called

    - by Jim Thio
    How does iOs know? Does each view has a pointer to it's controller? What happened? When we pop a viewController from navigation, does the navigationController arrange which view should be called? For example: If I added: [[BNUtilitiesQuick window] addSubview:[BNUtilitiesQuick searchController].view]; viewWillAppear will be called. However, window doesn't know the viewController. I am passing the view outlet of the controller not the controller. How can iOs 5 knows that it has to call [[BNUtilitiesQuick searchController] viewWillAppear:YES]

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  • UML binary association aggregatee has access to aggregator

    - by user314172
    Firstly, I'd like to thank those who answered my previous question ages ago. Currently I'm engaging more in the design phase UMLs, as this is my first medium scale deployment I'm entrusted with. This is extremely simple, but it bugs me so. If (Component) owns (Manager of Component), and (Manager of Component) has a reference to (Component) through which it manages it; how do you fully describe the relationship? I know it is aggregative, but how do you describe (Manager of Component) possessing a reference/pointer to the (Component) that physically owns the (Manager of Component) ? Example: Lidar owns a LidarManager

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  • Shell script exiting the loop after calling another script

    - by Johnyy
    Hi Guys, I have a shell script s1 calling another script s2 in a loop. However s1 can not seem to continue the loop after s2 returns. Commenting out the line that calls s2 will enable the loop to continue. s2 does copy of one file, s1 checks conditions and copy several files using s2. Can anyone give a pointer what is going on here? ... while read line s2 param1 param2 param3 echo "copy done" done < $tempfile echo "out of loop" ... "copy done" is printed, so is "out of loop"

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  • Get path to a file via flash

    - by jeffkolez
    I'm not a flash dev, but I'm turning to it to try and meet a requirement. I'm to allow a user to select a file on their computer, then pass it to my web application. I know it's not possible to do this using Javascript, hence wanting to use flash. First, is this possible? Second, can I get a pointer on how its done? To clarify: I'm just looking for the path to the file. I don't want to upload it.

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  • Are self-described / auto-descriptive services loosely or tightly coupled in a SOA architecture ?

    - by snowflake
    I consider a self-described / auto-descriptive service as a good thing in a SOA architecture, since (almost) everything you know to call the service is present in the service contract (such a WSDL). Sample of a non self-described service for me is Facebook Query Language (FQL http://wiki.developers.facebook.com/index.php/FQL), or any web service exchanging XML flow in a one String parameter for then parsing XML and performing treatments. Last ones seem further more technically decoupled, since technically you can switch implementations without technical impact on the caller, handling compatibility between implementations/versions at a business level. On the other side, having no strong interface (diluted into the service and its version), make the service tightly coupled to the existing implementation (more difficulty to interchange the service and to ensure perfect compatibility). This question is related to http://stackoverflow.com/questions/2503071/how-to-implement-loose-coupling-with-a-soa-architecture So, are self-described / auto-descriptive services loosely or tightly coupled in a SOA architecture ? What are the impacts regarding ESBs ? Any pointer will be appreciated.

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  • Deferred printing in Java

    - by Bober02
    I have a specific issue with general console printing and I was wondering whether anyone has a solution for it. I am trying to print a dataTable which would look like sth like this: Table ---------------------- Name |Surname | ---------------------- Mike |Mikhailowish| Rafaello|Mirena | and so on. In order to print the border of the bar I need to know what the maximum length of each column value is. I don't want to go through the whole database to find that out and then again to print it. I would rather like to do sth like: System.out.printLater(s); //herejust leave a pointer to a StringBuilder you will build ... s.append("--------"); ... System.out.printAllDeferred(); I understand the above is probably in 99.99999% chances impossible, but perhaps you guys have a clever way of achieving the above?

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  • How to name variables which are structs

    - by evilpie
    Hello, i often work on private projects using the WinApi, and as you might know, it has thousands of named and typedefed structs like MEMORY_BASIC_INFORMATION. I will stick to this one in my question, what still is preferred, or better when you want to name a variable of this type. Is there some kind of style guide for this case? For example if i need that variable for the VirtualQueryEx function. Some ideas: MEMORY_BASIC_INFORMATION memoryBasicInformation; MEMORY_BASIC_INFORMATION memory_basic_information; Just use the name of the struct non capitalized and with or without the underlines. MEMORY_BASIC_INFORMATION basicInformation; MEMORY_BASIC_INFORMATION information; Short form? MEMORY_BASIC_INFORMATION mbi; I often see this style, using the abbreviation of the struct name. MEMORY_BASIC_INFORMATION buffer; VirtualQueryEx defines the third parameter lpBuffer (where you pass the pointer to the struct), so using this name might be an idea, too. Cheers

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  • "Cannot use fixed local inside lambda expression"

    - by JulianR
    I have an XNA 3.0 project that compiled just fine in VS2008, but that gives compile errors in VS2010 (with XNA 4.0 CTP). The error: Cannot use fixed local 'depthPtr' inside an anonymous method, lambda expression, or query expression depthPtr is a fixed float* into an array, that is used inside a Parallel.For lambda expression from System.Threading. As I said, this compiled and ran just fine on VS2008, but it does not on VS2010, even when targeting .NET 3.5. Has this changed in .NET 4.0, and even so, shouldn't it still compile when I choose .NET 3.5 as the target framework? Searching for the term "Cannot use fixed local" yields exactly one (useless) result, both in Google and Bing. If this has changed, what is the reason for this? I can imagine capturing a fixed pointer-type in a closure could get a bit weird, is that why? So I'm guessing this is bad practice? And before anyone asks: no, the use of pointers is not absolutely critical here. I would still like to know though :)

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  • Trouble creating a makefile

    - by catia
    Hi everyone! I'm having some trouble making a Makefile. Write now I just compile everything every time. Although, the professor is ok with that, I do want to get it working faster and to avoid unnecessary compiling. Here's what I have. FILES= p6.cpp SetIter.cpp Node.cpp Set.cpp CFLAGS= -ansi -pendantic -Wall -Wextra CC= g++ MakePg6: p6.cpp SetIter.cpp Node.cpp Set.cpp $(CC) $(CFLAGS) $(FILES) -o pg6 Node.cpp - node class Set.cpp - uses nodes. Friend of Node. SetIter.cpp - gets a set and uses a pointer to iterator through I'm confused with some of the depencies arising from the friends thing and the point of lib.o being included in the Makefile as some sites have. Any help is greatly appreciated. Thanks in advance.

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  • Manipulating both unicode and ASCII character set in C#

    - by Murlex
    I have this mapping in my C# application string [,] unicode2Ascii = { { "&#3001;", "\x86" } }; ஹ - is the unicode value for a tamil literal "ஹ". This is the raw hex literal for the unicode value saved by MS Word as a byte sequence. I am trying to map these unicode value "strings" to a hex value under 255 (so as to accommodate non-unicode supported systems). I trying to use string.replace like this: S = S.replace(unicode2Ascii[0,0], unicode2Ascii[0,1]); However the resultant ouput has a ? instead of the actual hex 0x86 stored. Any pointer on how I could set the encoding for the second element of that array to something like windows-1252? Or is there a better way to do this conversion? thanks in advance

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  • Symfony 1.3: different form filters generated

    - by user248959
    Hi, i have this class in rs1/lib/filter/doctrine/FelizFormFilter.class.php <?php /** * Feliz filter form. * * @package rs * @subpackage filter * @author Your name here * @version SVN: $Id: sfDoctrineFormFilterTemplate.php 23810 2009-11-12 11:07:44Z Kris.Wallsmith $ */ class FelizFormFilter extends BaseFelizFormFilter { public function configure() { } } and this in rs2/lib/filter/doctrine/FelizFormFilter.class.php <?php /** * Feliz filter form. * * @package filters * @subpackage Feliz * * @version SVN: $Id: sfDoctrineFormFilterTemplate.php 11675 2008-09-19 15:21:38Z fabien $ */ class FelizFormFilter extends BaseFelizFormFilter { public function configure() { } } Both were generated using "php symfony doctrine:build --all --and-load" and the version of symfony is 1.3.4 in both. This is the schema of both cases: Feliz: columns: name: string(20) Could you tell me why are different? One more thing in Eclipse: when i go with the mouse pointer to the word "BaseFelizFormFilter", in the second case (rs2) the yellow window with the information about the class is showed, but in the first case that yellow popup is not showed. Why? Javi

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  • How to save/export a DOM element to an image?

    - by Don Don
    Hi, I have a web page which has a form element (with its ID known) and inside the form there are multiple DIVs, and the position of each div may be changed. What I'd like to do is: a) Save the current state of this form // var currentForm=document.forms['myFrm'].innerHTML; would probably suffice... b) Save or export the entire form with the most current position of each DIV to an image file. // how to save/export the javascript var of currentForm to an image file is the key question. Any help/pointer would be appreciated.

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  • C# Drag and Drop Effect with Overlay/Opaque Image

    - by CallMeLaNN
    Hi, I think this would be simple question and should be asked in the pas few years but unable to google around and dont know if there is a specific keyword. In c# WinForm I want to do drag and drop but I dont want the image of DragDropEffects Move, Copy or whatever. I want to display an image with half opaque. Just like Firefox when dragging an image, you would see the image folowing the mouse pointer like a ghost :) I already Implement DoDragDrop, DragEnter and DragDrop events. I just want to customize the dragging effects with overlay image.

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  • Strange behaviour of Android debugger in Eclipse when using Camera for preview.

    - by Buzzy
    Hi, I have an Android application that uses a SurfaceView subclass and Camera object to preview images before capture. Once I capture an image, I stop the preview and release the camera. Execution stops at any breakpoint after this. However, apart from the "Suspend" and "Terminate" icons, the rest are disabled. This is strange because the "Debug Current Instruction Pointer" is clearly at the said breakpoint and execution is already suspended. I can't perform any debugging operations and have no option but to terminate the session. Sometimes (very rarely), the session terminates by itself. I can confirm that this odd behavior takes place only after I preview the camera capture. I am fairly new to Android development. Is there some obvious mistake I am making? Any help would be highly appreciated.

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  • Regular Expression to match unlimited number of options

    - by Pekka
    I want to be able to parse file paths like this one: /var/www/index.(htm|html|php|shtml) into an ordered array: array("htm", "html", "php", "shtml") and then produce a list of alternatives: /var/www/index.htm /var/www/index.html /var/www/index.php /var/www/index.shtml Right now, I have a preg_match statement that can split two alternatives: preg_match_all ("/\(([^)]*)\|([^)]*)\)/", $path_resource, $matches); Could somebody give me a pointer how to extend this to accept an unlimited number of alternatives (at least two)? Just regarding the regular expression, the rest I can deal with. The rule is: The list needs to start with a ( and close with a ) There must be one | in the list (i.e. at least two alternatives) Any other occurrence(s) of ( or ) are to remain untouched.

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  • What does this error mean when using OpenAL in the iPhone Simulator?

    - by mystify
    I'm getting this in the console, when creating my OpenAL Sources and Buffers: Cannot find executable for CFBundle/CFPlugIn 0xf530d0 </Library/Audio/Plug-Ins/HAL/Hear.plugin> (not loaded) 2010-05-05 17:11:13.934 Testproj[43173:207] Cannot find function pointer HearCFPlugInFactory for factory 5268FAAB-0147-4272-93FD-4D60A2433C1C in CFBundle/CFPlugIn 0xf430d0 </Library/Audio/Plug-Ins/HAL/Hear.plugin> (not loaded) However, the sounds play nicely. I think HAL is not available on the iPhone, it's just on Mac OS X, right? Do you guys also get that error in the simulator when using OpenAL?

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