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  • How to learn proper C++?

    - by Chris
    While reading a long series of really, really interesting threads, I've come to a realization: I don't think I really know C++. I know C, I know classes, I know inheritance, I know templates (& the STL) and I know exceptions. Not C++. To clarify, I've been writing "C++" for more than 5 years now. I know C, and I know that C and C++ share a common subset. What I've begun to realize, though, is that more times than not, I wind up treating C++ something vaguely like "C with classes," although I do practice RAII. I've never used Boost, and have only read up on TR1 and C++0x - I haven't used any of these features in practice. I don't use namespaces. I see a list of #defines, and I think - "Gracious, that's horrible! Very un-C++-like," only to go and mindlessly write class wrappers for the sake of it, and I wind up with large numbers (maybe a few per class) of static methods, and for some reason, that just doesn't seem right lately. The professional in me yells "just get the job done," the academic yells "you should write proper C++ when writing C++" and I feel like the point of balance is somewhere in between. I'd like to note that I don't want to program "pure" C++ just for the sake of it. I know several languages. I have a good feel for what "Pythonic" is. I know what clean and clear PHP is. Good C code I can read and write better than English. The issue is that I learned C by example, and picked up C++ as a "series of modifications" to C. And a lot of my early C++ work was creating class wrappers for C libraries. I feel like my own personal C-heavy background while learning C++ has sort of... clouded my acceptance of C++ in it's own right, as it's own language. Do the weathered C++ lags here have any advice for me? Good examples of clean, sharp C++ to learn from? What habits of C does my inner-C++ really need to break from? My goal here is not to go forth and trumpet "good" C++ paradigm from rooftops for the sake of it. C and C++ are two different languages, and I want to start treating them that way. How? Where to start? Thanks in advance! Cheers, -Chris

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  • GridView items are displaying the wrong drawables sometimes.

    - by originalbryan
    I've implemented a GridView based on this tutorial. It works great unless open up the search dialog or rotate the screen then scroll around. When the search dialog and virtual keyboard appear, the drawables for each of my grid items shift. I can click on them and they do what I expect, except the drawable is wrong. The same problem happens when I go into landscape mode and scroll around. If I scroll down, up, the down again, the drawables are shuffled. For better illustration, let's say I have three objects, each with an image. Obj A shows an Apple Obj B shows a Banana Obj C shows a Cantaloupe When the shift occurs I end up with: Obj A shows an Cantaloupe Obj B shows a Banana Obj C shows a Apple The problem isn't consistent between the two causes (search dialog and screen rotate n' scroll), but each cause itself is consistent. Scrolling around repeatedly reveals a pattern as does the search dialog appearing. How can I stop this from happening?

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  • Copying a Polymorphic object in C++

    - by doron
    I have base-class Base from which is derived Derived1, Derived2 and Derived3. I have constructed an instance for one of the the derived classes which I store as Base* a. I now need to make a deep copy of the object which I will store as Base* b. As far as I know, the normal way of copying a class is to use copy constructors and to overload operator=. However since I don't know whether a is of type Derived1, Derived2 or Derived3, I cannot think of a way of using either the copy constructor or operator=. The only way I can think of to cleanly make this work is to implement something like: class Base { public: virtual Base* Clone() = 0; }; and the implement Clone in in the derived class as in: class Derivedn : public Base { public: Base* Clone() { Derived1* ret = new Derived1; copy all the data members } }; Java tends to use Clone quite a bit is there more of a C++ way of doing this?

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  • Can this way of storing typed objects be improved?

    - by Pindatjuh
    This is an "can it be improved"-question. Topic: Storing typed objects in memory. Background information: I'm building a compiler for the x86-32 Windows platform for my language. My goal includes typed objects. Idea: Every primitive is a semi-class (it can be used as if it was a normal class, but it's stored more compact). Every class is represented by primitives and some meta-data (containing class-properties, inheritance stuff, etc.). The meta-data is complex: it doesn't use fields but instead context-switches. For primitives, the meta-data is very small, compared to a "real" class, which is alot bigger. This enables another idea that "primitives are objects", in my language, which I found nessecairy. Example: If I have an array of 32 booleans, then the pure content of this array is exactly 4 byte (32 bits of booleans). The meta-data will contain flags that the type is an array of booleans, which contains 32 entries. The meta-data is very compacted, on bit-level: using a sort of "packing" mechanism, which is read by a FSM at runtime, when doing inspection of the type (like when passing the object to methods for checking, etc.) For instance (read from left to right, top to bottom, remember vertical position when going to the right, and check nearest column header for meaning of switch): Primitive? Array? Type-Meta 1 Byte? || Size (1 byte) 1 1 [...] 1 [...] done 0 2 Bytes? || Size (2 bytes) 1 [...] done || Size (4 bytes) 0 [...] done Integer? 1 Byte? 2 Bytes? 0 1 0 1 done 1 done 0 done Boolean? Byte? 0 1 0 done 1 done More-Primitives 0 .... Class-Stuff (Huge) 0 ... (After reaching done the data is inserted. || = byte alignment. [...] is variable sized. ... is not described here, for simplicity. And let's call them cost-based-data-structures.) For an array of 32 booleans containing all true values, the memory for this type would be (read top-down): 1 Primitive 1 Array 1 ArrayType: Primitive 0 Not-Array 0 Not-Integer 1 Boolean 0 Not-Byte (thus bit) 1 Integer Size: 1 Byte 00100000 Array size 01010101 01010101 01010101 01010101 Data (user defined) Thus, 8 bytes represent 32 booleans in an array: 11100101 00100000 01010101 01010101 01010101 01010101 How can I improve this? (Both performance- and memory-consumption wise)

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  • How to programaticaly gain root privileges ?

    - by ereOn
    I am writing a software (in C++, for Linux/Mac OSX) which runs as a non-privileged user and but needs root privileges at some point (to create a new virtual device). Running this program as root is not a option (mainly for security issues) and I need to know the identity (uid) of the "real" user. Is there a way to mimic the "sudo" command behavior (ask for user password) to temporarily gain root privileges and perform the particular task ? If so, which functions would I use ? Thank you very much for your help !

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  • Apache mod rewrite .htaccess

    - by Sanjay
    Hello, Can anyone help to solve problem with overriding in apache2 ? I have enabled mod_rewrite in apache2. ut apache just ignores my .htaccess file with rewrite rules. When I add this line to my .htaccess file: This is my virtual host configuration: <VirtualHost *:80> ServerName www.modomain.eu ServerAlias mydomain.eu *.mydomain.eu mydomain.es *.mydomain.es DocumentRoot /home/sites/mydomain.es <Directory /home/sites/mydomain.es> allowoverride none </Directory> </VirtualHost>

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  • django getting current user id

    - by dana
    hello, i have a mini app where users can login, view their profile, and follow each other. 'Follow' is a relation like a regular 'friend' relationship in virtual communities, but it is not necessarily reciprocal, meaning that one can follow a user, without the need that the user to be following back that person who follows him. my problem is: if i am a logged in user, and i navigate to a profile X, and push the button follow, how can i take the current profile id ?(current profile meaning the profile that I, the logged in user, am viewing right now.) the view: def follow(request): if request.method == 'POST': form = FollowForm(request.POST) if form.is_valid(): new_obj = form.save(commit=False) new_obj.initiated_by = request.user u = User.objects. what here? new_obj.follow = u new_obj.save() return HttpResponseRedirect('.') else: form = FollowForm() return render_to_response('followme/follow.html', { 'form': form, }, context_instance=RequestContext(request)) thanks in advance!

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  • asp.net Configuration Error on host

    - by zey
    I uploaded my asp.net site to hosting site , and my site browse correctly . But when I go to login url , it's show me the error Configuration Error Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately. Parser Error Message: It is an error to use a section registered as allowDefinition='MachineToApplication' beyond application level. This error can be caused by a virtual directory not being configured as an application in IIS. Source Error: Line 23: </assemblies> Line 24: </compilation> Line 25: <authentication mode="Forms"> Line 26: <forms loginUrl="~/Account/Login.aspx" timeout="2880" /> Line 27: </authentication> How can I fix it ?

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  • Using Visual Studio 2005 (32bit) on a Windows 7 64bit machine.

    - by Krakkos
    I need to use Visual Studio 2005 (C++) on my new laptop - a Sony Vaio with Windows 7 64bit.. I don't need to develop for a 64bit environment, my work is all 32bit, so how can I be sure that I can still develop/debug/test for a 32bit target environment using VS2005 on a 64bit machine....? What's the best option: 1) Just install VS2005 on Windows 7 64bit and carry on.. (suspect problems with 64bit runtime libs..?) 2) Dual boot the laptop with Windows XP 32bit. 3) Run some kind of Virtual Machine with Windows XP in it... (I don't have a VM yet, but would look into it) Thanks

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  • Tab widget example not running

    - by michbeck
    I'm trying to reproduce the tabwidget example (http://developer.android.com/resources/tutorials/views/hello-tabwidget.html). I'm not really sure what's the problem, I got no errors while compiling, but i cannot see the application on the emulators screen. It would be excellent if maybe anyone could have a look at my classes and tell me what's my mistake? I've packed my project here: http://etanto.com/TabTest.zip here's the console dump while the run: [2010-06-10 09:18:34 - TabTest] Launching a new emulator with Virtual Device 'Virtual1' [2010-06-10 09:18:35 - TabTest] New emulator found: emulator-5554 [2010-06-10 09:18:35 - TabTest] Waiting for HOME ('android.process.acore') to be launched... [2010-06-10 09:19:05 - TabTest] WARNING: Application does not specify an API level requirement! [2010-06-10 09:19:05 - TabTest] Device API version is 8 (Android 2.2) [2010-06-10 09:19:05 - TabTest] HOME is up on device 'emulator-5554' [2010-06-10 09:19:05 - TabTest] Uploading TabTest.apk onto device 'emulator-5554' [2010-06-10 09:19:05 - TabTest] Installing TabTest.apk... [2010-06-10 09:19:22 - TabTest] Success! [2010-06-10 09:19:22 - TabTest] \TabTest\bin\TabTest.apk installed on device [2010-06-10 09:19:22 - TabTest] Done!

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  • A good approach to db planing for reporting service

    - by Itay Moav
    The scenario: Big system (~200 tables). 60,000 users. Complex reports that will require me to do multiple queries for each report and even those will be complex queries with inner queries all over the place + some processing in PHP. I have seen an approach, which I am not sure about: Having one centralized, de-normalized, table that registers any activity in the system which is reportable. This table will hold mostly foreign keys, so she should be fairly compact and fast. So, for example (My system is a virtual learning management system), A user enrolls to course, the table stores the user id, date, course id, organization id, activity type (enrollment). Of course I also store this data in a normalized DB, which the actual application uses. Pros I see: easy, maintainable queries and code to process data and fast retrieval. Cons: there is a danger of the de-normalized table to be out of sync with the real DB. Is this approach worth considering, or (preferably from experience) is total $#%#%t?

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  • How to convert a function that returns a int to a function that returns a bool using boost::bind?

    - by user814628
    I have something like the following: struct A{ virtual int derp(){ if(herp()) return 1; else return 0; } void slurp(){ boost::function<bool(int x, int y> purp = /** boost bind derp to match lvalue sig **/; } } Any ideas? I want to create the function prup which basically calls derp and ignores the (x,y) passed in. I need something like bool purp(int x, int y){ return derp(); } but want to avoid creating it as a member function, and rather just create it locally if possible?

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  • Full-Text Search in SQL Server Express Won't Recognize Latest IFilters

    - by Brandon King
    I'm having difficulty getting full-text search working in SQL Server 2008 Express with Advanced Services. I have a table loaded with .DOCX files as varbinary(MAX) data that I want to use for a full-text catalog, but it doesn't seem to recognize the .DOCX format. Here are the steps that I've taken... Installed the latest Filter Pack 2.0 Exec sp_fulltext_service 'load_os_resources', 1 Exec sys.sp_help_fulltext_system_components 'all' (NOTE: .DOCX is not shown as a filter) Building the full-text catalog fails to identify any key words I initially thought there might be a conflict between x86 SQL Express and x64 Filter Pack on my Windows 7 machine, but I just tried it with everything x86 in a Windows XP virtual machine and got the same result.

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  • Template type deduction with a non-copyable class

    - by Evan Teran
    Suppose I have an autolocker class which looks something like this: template <T> class autolocker { public: autolocker(T *l) : lock(l) { lock->lock(); } ~autolocker() { lock->unlock(); } private: autolocker(const autolocker&); autolocker& operator=(const autolocker&); private: T *lock; } Obviously the goal is to be able to use this autolocker with anything that has a lock/unlock method without resorting to virtual functions. Currently, it's simple enough to use like this: autolocker<some_lock_t> lock(&my_lock); // my_lock is of type "some_lock_t" but it is illegal to do: autolocker lock(&my_lock); // this would be ideal Is there anyway to get template type deduction to play nice with this (keep in my autolocker is non-copyable). Or is it just easiest to just specify the type?

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  • Visual Studio 2010 "Not enough storage is available to process this command"

    - by Daniel Perez
    I'm fighting with VS 2010 and this error that seems to be very common in previous versions, but it looks like not everyone is having it in the latest version. I've got VS 2010 SP1 and I'm getting this error quite often. The problem is that it's not even enough to restart VS in order to make it go away, I usually have to restart my pc, and i'm losing a lot of time doing this (it's quite frequent) I've got Windows 7 32bits (can't upgrade to 64 bits, the company doesn't allow it), and I can't do things like creating another solution (please don't reply this :) ) I've used the command to make devenv.exe LARGEADDRESSAWARE, but the error keeps on happening My virtual memory size is set to automatic, and the weird thing is that VS doesn't even take 2gb of ram, so I don't know if the error is really because it's lacking memory, or if it's some bug in the program any ideas, things to try, something?

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  • C++ visitor pattern handling templated string types?

    - by Steve the Plant
    I'm trying to use the visitor pattern to serialize the contents of objects. However one snag I'm hitting is when I'm visiting strings. My strings are of a templated type, similar to STL's basic_string. So something like: basic_string<char_type, memory_allocator, other_possible_stuff> \\ many variations possible! Since I can have very many different templated string types, I can't go and add them to my visitor interface. It would be ridiculous. But I can't add templates to my VisitString method because C++ prevents using templates parameters in virtual methods. So what are my options to work around this?

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  • Why does my program occasionally segfault when out of memory rather than throwing std::bad_alloc?

    - by Bradford Larsen
    I have a program that implements several heuristic search algorithms and several domains, designed to experimentally evaluate the various algorithms. The program is written in C++, built using the GNU toolchain, and run on a 64-bit Ubuntu system. When I run my experiments, I use bash's ulimit command to limit the amount of virtual memory the process can use, so that my test system does not start swapping. Certain algorithm/test instance combinations hit the memory limit I have defined. Most of the time, the program throws an std::bad_alloc exception, which is printed by the default handler, at which point the program terminates. Occasionally, rather than this happening, the program simply segfaults. Why does my program occasionally segfault when out of memory, rather than reporting an unhandled std::bad_alloc and terminating?

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  • How can I utilize or mimic Application OnStart in an HttpModule?

    - by Sailing Judo
    We are trying to remove the global.asax from our many web applications in favor of HttpModules that are in a common code base. This works really well for many application events such as BeginRequest and PostAuthentication, but there is no Application Start event exposed in the HttpModule. I can think of a couple of smelly ways to overcome this deficit. For example, I can probably do this: protected virtual void BeginRequest(object sender, EventArgs e) { Log.Debug("Entered BeginRequest..."); var app = HttpContext.Current.Application; var hasBeenSet app["HasBeenExecuted"] == null ? false : true; if(!hasBeenSet) { app.Lock(); // ... do app level code app.Add("HasBeenSet", true); app.Unlock(); } // do regular begin request stuff ... } But this just doesn't smell well to me. What is the best way to invoke some application begin logic without having a global.asax?

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  • Regex for Searching for Text Not Preceeded By a Specific String

    - by James
    Hi, I am working on a web site with several other developers and we have had problems where people commit JavaScript code with AJAX calls that use URL's relative to the site root. An example would be /Home/Index which will not work if the site is hosted in a virtual directory. To get round the problem we use a $.url() method to convert it to a full path, e.g. $("#container").load($.url("/Home/Index")) I am trying to write a unit test that will search each JavaScript file and find places where the $.url method is not being used. The only problem is that I cannot seem to write a regex expression to do this. I have tried the following: (?!\$\.url\()"(/\w*)+" But this does not work. I cannot find a way to say that I don't want the $.url in front. Does anyone know if this is possible? Note that I need regular expressions that are compatible with .NET Thanks.

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  • How to flush data in php and disconnect user but keep the script alive

    - by Rodrigo
    This is a trick question, while developing a php+ajax application i felt into some long queries, nothing wrong with them, but they could be done in background. I know that there's a way to just send a reply to user while throwing the real processing to another process by exec(), however it dosen't feels right for me, this might generate exploits and it's not pratical on making it compatible with virtual servers and cross platform. PHP offers the ob_* functions although they help on flushing the cache, but the user will keep connected until the script is running. I'm wondering if there's an alternate to exec to keep a script running after sending data to user and closing connection/thread with apache, or a less "dirty" way to have processing data sent to another script.

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  • Static source code analysis with LLVM

    - by Phong
    I recently discover the LLVM (low level virtual machine) project, and from what I have heard It can be used to performed static analysis on a source code. I would like to know if it is possible to extract the different function call through function pointer (find the caller function and the callee function) in a program. I could find the kind of information in the website so it would be really helpful if you could tell me if such an library already exist in LLVM or can you point me to the good direction on how to build it myself (existing source code, reference, tutorial, example...). EDIT: With my analysis I actually want to extract caller/callee function call. In the case of a function pointer, I would like to return a set of possible callee. both caller and callee must be define in the source code (this does not include third party function in a library).

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  • Has anyone managed to get Visual Studio 2003 running on Windows 7?

    - by Jeremy White
    Yes, I know... I could set up a virtual machine running XP. Unfortunately our build environment is such that we need to be running VC2003, 2005 and 2008 concurrently and it would be much more convenient if I could run 2003 natively on Windows 7 for the few projects we have that require it. I realize some things may not be available in the IDE, but I was able to run 2003 under windows Vista and if I could get the same base level of functionality under Windows 7 I would be extremely happy. Right now I get an error opening the *.pdb file when I compile after switching vc2003 to run as Administrator under compatibility mode for XP SP 2. Thanks!

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  • TFS 2010 Sharepoint Web Part error

    - by Shane
    I downloaded: Microsoft® Visual Studio® 2010 and Team Foundation Server® 2010 Beta 2 for Microsoft® Virtual PC 2007 SP1 Image When I go into the default installation of TFS project site in Sharepoint ( http://vs2010beta2/sites/DefaultCollection/IBuySpy/Dashboards/ProjectDashboard_wss.aspx ) I get this error on the webparts. There are no accessible team projects in this Team Project Collection. Contact your Team Foundation Server administrator. In the Team Server Admin Console - Team Project Collection - Team Projects tab the projects are there. This is the default installation. Any suggestions???

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  • Reverting back to previous ADT plugin

    - by sdfwer
    Now I was wondering if anyone has been able to accomplish reverting to a previous ADT plugin. The reason for this is because I am using an open source jar and I am getting the following errors on my LogCat such as: unable to resolve virtual method unable to find class referenced in signature unable to resolve new-instance The effect of this causes an error on running my android application on the debugger. I was using android ADT 15 before now I am updated to 17. Please help on finding a solution to resolve the issue. Edit* Forgot to add in The error "java.lang.NoClassDefFoundError". In simple terms it can't find classes or methods the attached jar even though it allows it.

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  • Running matlab in the background

    - by msandbot
    Hi, I am running matlab on 48 virtual machines and would like to automate it. I ssh into the machines then use matlab -r matlab_command > outfile.txt & to get the process to run in the background and run fine when I logout. The only problem is that when i jobs my process is stopped and won't start until I fg ^z bg. Is there a matlab flag so that I can run it in the background without having it stop? Thanks, Mike

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