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• Crash generated during destruction of hash_map

  - by Alien01

  I am using hash_map in application as typedef hash_map<DWORD,CComPtr<IInterfaceXX>> MapDword2Interface; In main application I am using static instance of this map static MapDword2Interface m_mapDword2Interface; I have got one crash dump from one of the client machines which point to the crash in clearing this map I opened that crash dump and here is assembly during debugging > call std::list<std::pair<unsigned long const ,ATL::CComPtr<IInterfaceXX> >,std::allocator<std::pair<unsigned long const ,ATL::CComPtr<IInterfaceXX> > > >::clear > mov eax,dword ptr [CMainApp::m_mapDword2Interface+8 (49XXXXX)] Here is code where crash dump is pointing. Below code is from stl:list file void clear() { // erase all #if _HAS_ITERATOR_DEBUGGING this->_Orphan_ptr(*this, 0); #endif /* _HAS_ITERATOR_DEBUGGING */ _Nodeptr _Pnext; _Nodeptr _Pnode = _Nextnode(_Myhead); _Nextnode(_Myhead) = _Myhead; _Prevnode(_Myhead) = _Myhead; _Mysize = 0; for (; _Pnode != _Myhead; _Pnode = _Pnext) { // delete an element _Pnext = _Nextnode(_Pnode); this->_Alnod.destroy(_Pnode); this->_Alnod.deallocate(_Pnode, 1); } } Crash is pointing to the this->_Alnod.destroy(_Pnode); statement in above code. I am not able to guess it, what could be reason. Any ideas??? How can I make sure, even is there is something wrong with the map , it should not crash?

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• Execute binary from memory in C# .net with binary protected from a 3rd party software

  - by NoobTom

  i've the following scenario: i've a C# application.exe i pack application.exe inside TheMida, a software anti-piracy/reverse engineering. i encrypt application.exe with aes256. (i wrote my own aes encryption/decryption and it is working) Now, when i want to execute my application i do the following: decrypt application.exe in memory execute the application.exe with the following code: BinaryReader br = new BinaryReader(decOutput); byte[] bin = br.ReadBytes(Convert.ToInt32(decOutput.Length)); decOutput.Close(); br.Close(); // load the bytes into Assembly Assembly a = Assembly.Load(bin); // search for the Entry Point MethodInfo method = a.EntryPoint; if (method != null) { // create an istance of the Startup form Main method object o = a.CreateInstance(method.Name); // invoke the application starting point method.Invoke(o, null); the application does not execute correctly. Now, the problem i think, is that this method is only to execute .NET executable. Since i packed my application.exe inside TheMida this does not work. Is there a workaround to this situation? Any suggestion? Thank you in advance.

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• static block instance block java Order

  - by Rollerball

  Having read this question In what order are the different parts of a class initialized when a class is loaded in the JVM? and the related JLS. I would like to know in more detail why for example having class Animal (superclass) and class Dog (subclass) as following: class Animal { static{ System.out.println("This is Animal's static block speaking"): } { System.out.println("This is Animal's instance block speaking"); } class Dog{ static{ System.out.println("This is Dog's static block speaking"); } { System.out.println("This is Dog's instance block speaking"); } public static void main (String [] args) { Dog dog = new Dog(); } } Ok before instantiating a class its direct superclass needs to be initialized (therefore all the statics variables and block need to be executed). So basically the question is: Why after initializing the static variables and static blocks of the super class, control goes down to the subclass for static variables initialization rather then finishing off the initialization of also the instance member? The control goes like: superclass (Animal): static variables and static blocks subclass (Dog): static variables and static blocks superclass (Animal): instance variables and instance blocks sublcass (Dog):instance variables and instance blocks What is the reason why it is in this way rather than : superclass -> static members superclass -> instance members subclass -> static members sublcass-> instance members

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• My android tests don't get internet access!

  - by Malachii

  The subject says it all. My application gets internet access thanks to the android.permission.INTERNET permission, but my test cases don't while using the instrumentation test runner. This means I can't test my server IO routines in my test cases. What's up? Here's my manifest in case it helps you. Thanks! Sorry about the lack of indents - could not get it working on short notice with this site. Thanks! <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.helloandroid" android:versionCode="1" android:versionName="1.0"> <uses-permission android:name="android.permission.INTERNET"></uses-permission> <application android:icon="@drawable/icon" android:label="@string/app_name"> <uses-library android:name="android.test.runner" /> <activity android:name=".HelloAndroid" android:label="@string/app_name"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> <uses-sdk android:minSdkVersion="2" /> <instrumentation android:name="android.test.InstrumentationTestRunner" android:targetPackage="qnext.mobile.redirect" android:label="Qnext Redirect Tests" /> </manifest>

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• c++ multithread

  - by chnet

  I use C++ to implement a thread class. My code shows in the following. I have a problem about how to access thread data. In the class Thread, I create a thread use pthread_create() function. then it calls EntryPoint() function to start thread created. In the Run function, I want to access the mask variable, it always shows segment fault. So, my question is whether the new created thread copy the data in original class? How to access the thread own data? class Thread { public: int mask; pthread_t thread; Thread( int ); void start(); static void * EntryPoint (void *); void Run(); }; Thread::Thread( int a) { mask =a; } void Thread::Run() { cout<<"thread begin to run" <<endl; cout << mask <<endl; // it always show segmentfault here } void * Thread::EntryPoint(void * pthis) { cout << "entry" <<endl; Thread *pt = (Thread *) pthis; pt->Run(); } void Thread::start() { pthread_create(&thread, NULL, EntryPoint, (void *)ThreadId ); pthread_join(thread, NULL); } int main() { int input_array[8]={3,1,2,5,6,8,7,4}; Thread t1(1); t1.start(); }

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• Beginner: Restore previously serialized JFrame-object, how?

  - by elementz

  Hi all. I have managed to serialize my very basic GUI-object containing a JTextArea and a few buttons to a file 'test.ser'. Now, I would like to completely restore the previously saved state from 'test.ser', but seem to have a misconception of how to properly deserialize an objects state. The class MyFrame creates the JFrame and serializes it. Now I tried to deserialize like so: public class Deserialize { static Deserialize ds; MyFrame frame; public static void main(String[] args) { try { ds.deserialize(); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public void deserialize() throws ClassNotFoundException { try { ObjectInputStream ois = new ObjectInputStream(new FileInputStream("test.ser")); frame = (MyFrame) ois.readObject(); ois.close(); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } Maybe somebody could point me into the direction where my misconception is? Thx in advance!

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• Problems running XNA game on 64-bit Windows 7

  - by Tesserex

  I'm having problems getting my game engine to run on my brother's machine, which is running 64-bit Windows 7. I'm developing on 32-bit XP SP2. My app uses XNA, FMOD.NET, and another dll I wrote entirely in C#. Everything is targeted to x86, not AnyCPU. I've read that this is required for XNA to work because there is no 64-bit xna framework. I recompiled FMOD.NET as x86 as well and made sure to be using the 32-bit version of the native dll. So I don't see any problems there. However when he tries to run my app, it gives an error which is mysterious, but not unheard of. A FileNotFoundException with an empty file name, and the top of the stack trace is in my main form constructor. The message is The specified module could not be found. (Exception from HRESULT: 0x8007007E) I found some threads online about this error, all with very vague, mixed, and fuzzy responses that don't really help me. Most remind people to target x86. Some say check that they have all the dlls necessary. I gave my brother Microsoft.Xna.Framework.dll, but does he need to install the entire XNA redistributable package? When I take everything I sent him and stick it in a random directory, it still runs fine for me. I developed the game in VS2008, not in game studio, using XNA 3.0 and a Windows Forms control that uses XNA drawing which I found in an msdn tutorial. I would also like to avoid requiring a full installer if possible. Any insight? Please?

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• What's the correct way to do a "catch all" error check on an fstream output operation?

  - by Truncheon

  What's the correct way to check for a general error when sending data to an fstream? UPDATE: My main concern regards some things I've been hearing about a delay between output and any data being physically written to the hard disk. My assumption was that the command "save_file_obj << save_str" would only send data to some kind of buffer and that the following check "if (save_file_obj.bad())" would not be any use in determining if there was an OS or hardware problem. I just wanted to know what was the definitive "catch all" way to send a string to a file and check to make certain that it was written to the disk, before carrying out any following actions such as closing the program. I have the following code... int Saver::output() { save_file_handle.open(file_name.c_str()); if (save_file_handle.is_open()) { save_file_handle << save_str.c_str(); if (save_file_handle.bad()) { x_message("Error - failed to save file"); return 0; } save_file_handle.close(); if (save_file_handle.bad()) { x_message("Error - failed to save file"); return 0; } return 1; } else { x_message("Error - couldn't open save file"); return 0; } }

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• Comparison operators not supported for type IList when Paging data in Linq to Sql

  - by Dan

  I can understand what the error is saying - it can't compare a list. Not a problem, other than the fact that I don't know how to not have it compare a list when I want to page through a model with a list as a property. My Model: Event : IEvent int Id string Title // Other stuff.. LazyList<EventDate> Dates // The "problem" property Method which pages the data (truncated): public JsonResult JsonEventList(int skip, int take) { var query = _eventService.GetEvents(); // Do some filtering, then page data.. query = query.Skip(skip).Take(take); return Json(query.ToArray()); } As I said, the above is truncated quite a bit, leaving only the main point of the function: filter, page and return JSON'd data. The exception occurs when I enumerate (.ToArray()). The Event object is really only used to list the common objects of all the event types (Meetings, Birthdays, etc - for example). It still implements IEvent like the other types, so I can't just remove the LazyList<EventDate> Dates' property unless I no longer implementIEvent` Anyway, is there a way to avoid this? I don't really want to compare a LazyList when I page, but I do not know how to resolve this issue. Thank you in advance! :)

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• What is the best approach to 2D collision detection on the iPhone?

  - by Magic Bullet Dave

  Been working on this problem of collision detection and there appears to be 3 main approaches I could take: Sprite and mask approach. (AND the overlap of the sprites and check for a non-zero number in the resulting sprite pixel data). Bounding circles, rectangles or polygons. (Create one or more shapes that enclose the sprites and do the basic maths to check for overlaps). Use an existing sprite library. The first approach, even though it would have been the way I would have done it in the old days of 16x16 sprite blocks, it appears that there just isn’t an easy way of getting at the individual image pixel data and/or alpha channel within Quartz (or OPENGL for that matter). Detecting the overlap of the bounding box is easy, but then creating a 3rd image from the overlap and then testing it for pixels is complicated and my gut feel is that even if we could get it to work would be slow. Am I missing something neat here? The second approach involves dividing up our sprites into several polygons and testing them for overlaps. The more polygons the more accurate the collision detection. The benefit is that it is fast, and can be accurate. The downside is it makes the sprite creation more complicated. i.e., we have to create the polygons for each sprite. For speed the best approach is to create a tree of polygons. The 3rd approach I’m not sure about as it involves buying code (or using an open source licence). I am not sure what the best library to use is or whether this would make life easier or give us a problem integrating this into our app. So in short I am favouring the polygon and tree approach and would appreciate you views on this before I go and write lots of code. Best regards Dave

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• ASP.Net MVC: Showing the same data using different layouts...

  - by vdh_ant

  Hi guys I'm wanting to create a page that allows the users to select how they would like to view their data - i.e. summary (which supports grouping), grid (which supports grouping), table (which supports grouping), map, time line, xml, json etc. Now each layout would probably have different use a different view model, which inherit from a common base class/view model. The reason being that each layout needs the object structure that it deals with to be different (some need hierarchical others a flatter structure). Each layout would call the same repository method and each layout would support the same functionality, i.e. searching and filtering (hence these controls would be shared between layouts). The main exception to this would be sorting which only grid and table views would need to support. Now my question is given this what do people think is the best approach. Using DisplayFor to handle the rendering of the different types? Also how do I work this with the actions... I would imagine that I would use the one action, and pass in the layout types, but then how does this support the grouping required for the summary, grid and table views. Do i treat each grouping as just a layout type Also how would this work from a URL point of view - what do people think is the template to support this layout functionality Cheers Anthony

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• php when to use get method?

  - by user329394

  how all, when is the right time to use $_GET['data']? i want to pass value of userid from page A to page B by using popup javascript. $qry="SELECT * FROM dbase WHERE id='".$id."'"; $sql=mysql_query($qry); $rs=mysql_fetch_array($sql); <script language="JavaScript"> function myPopup() { window.open( "<?=$CFG->wwwroot.'/ptk/main.php?task=ptk_checkapp&id='.$rs['userid'];?>" ,"myWindow", "status = 1, height = 500, width = 500, scrollbars=yes,toolbar=no,directories=no,location=no,menubar=no, resizable='yes';" ) } </script> calling by hyperlink: <a href="#" onclick="myPopup()"> <?=ucwords(strtolower($rs->nama));?> </a> It seems that , the $rs['user'] dont hold any value on it. can tell me what problem or may be solution? thank you very much.

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• Why am i getting same values of different JSON date values?

  - by Maxood

  I do not know the reason why am i getting same values of different JSON date values. Here is my code for parsing date values in JSON date format: package com.jsondate.parsing; import java.text.SimpleDateFormat; import java.util.Date; import android.app.Activity; import android.os.Bundle; import android.util.Log; import android.widget.TextView; public class JSONDateParsing extends Activity { /** Called when the activity is first created. */ String myString; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); TextView tv = new TextView(this); //Date d = (new Date(1266029455L)); //Date d = (new Date(1266312467L)); Date d = (new Date(1266036226L)); //String s = d.getDate() + "-" + d.getMonth() + "-" + d.getYear() + d.getHours() + d.getMinutes() + d.getSeconds(); // SimpleDateFormat sdf=new SimpleDateFormat("yyyy MMM dd @ hh:mm aa"); //Toast.makeText(this, d.toString(), Toast.LENGTH_SHORT); Log.e("Value:", d.toString()); myString = d.toString(); String []words = myString.split(" "); for(int i = 0;i < words.length; i++) Log.e("Value:", words[i]); myString = words[2] + "-" + words[1] + "-" + words[5] + " " + words[3]; tv.setText(myString); setContentView(tv); } }

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• php parsing speed optimization

  - by Arnaud

  I would like to add tooltip or generate link according to the element available in the database, for exemple if the html page printed is: to reboot your linux host in single-user mode you can ... I will use explode(" ", $row[page]) and the idea is now to lookup for every single word in the page to find out if they have a related referance in this exemple let's say i've got a table referance an one entry for reboot and one for linux reboot: restart a computeur linux: operating system now my output will look like (replaced < and by @) to @a href="ref/reboot"@reboot@/a@ your @a href="ref/linux"@linux@/a@ host in single-user mode you can ... Instead of have a static list generated when I saved the content, if I add more keyword in the future, then the text will become more interactive. My main concerne and question is how can I create a efficient enough process to do it ? Should I store all the db entry in an array and compare them ? Do an sql query for each word (seems to be crazy) Dump the table in a file and use a very long regex or a "grep -f pattern data" way of doing it? Or or or or I'm sure it must be a better way of doing it, just don't have a clue about it, or maybe this will be far too resource un-friendly and I should avoid doing such things. Cheers!

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• how to implement a sparse_vector class

  - by Neil G

  I am implementing a templated sparse_vector class. It's like a vector, but it only stores elements that are different from their default constructed value. So, sparse_vector would store the index-value pairs for all indices whose value is not T(). I am basing my implementation on existing sparse vectors in numeric libraries-- though mine will handle non-numeric types T as well. I looked at boost::numeric::ublas::coordinate_vector and eigen::SparseVector. Both store: size_t* indices_; // a dynamic array T* values_; // a dynamic array int size_; int capacity_; Why don't they simply use vector<pair<size_t, T>> data_; My main question is what are the pros and cons of both systems, and which is ultimately better? The vector of pairs manages size_ and capacity_ for you, and simplifies the accompanying iterator classes; it also has one memory block instead of two, so it incurs half the reallocations, and might have better locality of reference. The other solution might search more quickly since the cache lines fill up with only index data during a search. There might also be some alignment advantages if T is an 8-byte type? It seems to me that vector of pairs is the better solution, yet both containers chose the other solution. Why?

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• Use Struct as a Ptr/class? Need a fix .NET

  - by acidzombie24

  I wrote a bunch of code and i would like to fix it the fastest way possible. I'll describe my problem in a easier way. I have apples and oranges, they are both Point and in the list apples, oranges. I create a PictureBox and draw the apple/oranges on screen and move them around and update the Point via Tag. The problem now is since its a struct the tag is a copy so the original elements in the list are not update. So, how do i update them? I consider using Point? But those seem to be readonly. So the only solution i can think of is Clear the list, iterate through all the controls then check the picturebox property to check if the image is a apple or orange then add it to a list I really only thought of this solution typing this question, but my main question is, is there a better way? Is there some List<Ptr<Point>> class i can use so when i update the apples or oranges through the tag the element in the list will update as a class would?

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• NSPredicate cause update editing to return NSFetchedResultsChangeDelete not NSFetchedResultsChangeUp

  - by Matthew Weiss

  I have predicate inside of - (NSFetchedResultsController *)fetchedResultsController in a standard way starting from the CoreDataBook example. NSPredicate *predicate = [NSPredicate predicateWithFormat:@"state=%@ && date = %@ && date < %@", @"1",fromDate,toDate]; [fetchRequest setPredicate:predicate]; This works fine however when editing an item, it returns with NSFetchedResultsChangeDelete not Update. When the main view returns, it is missing the item. If I restart the simulator the delete was not saved and the correct editing result is shown the the predicate working correctly. case NSFetchedResultsChangeDelete: [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade]; break; I can confirm the behavior by commenting out the two predicate lines ONLY and then all works as it should correctly returning with the full set after editing and calling NSFetchedResultsChangeUpdate instead of NSFetchedResultsChangeDelete. I have read http://matteocaldari.it/2009/11/multiple-contexts-controllers-delegates-and-coredata-bug who reports similar behavior but I have not found a work around to my problem. I can

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• Strategy for WCF server with .Net clients and Android clients?

  - by D.H.

  I am using WCF to write a server that should be able to communicate with .Net clients, Android clients and possibly other types of clients. The main type of client is a desktop application that will be written in .Net. This client will usually be on the same intranet as the server. It will make an initial call to the server to get the current state of the system and will then receive updates from the server whenever a value changes. These updates are frequent, perhaps once a second. The Android clients will connect over the Internet. This client is also interested in updates, but it is not as critical as for the desktop client so a (less frequent) polling scenario might be acceptable. All clients will have to login to use the services, and when connecting over the Internet the connection should be secure. I am familiar with WCF but I am not sure what bindings are most appropriate for the scenario and what security solution to use. Also, I have not used Android, but I would like to make it as simple as possible for the person implementing the Android client to consume my services. So, what is my strategy?

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• String operations

  - by NEO

  I am trying to find the most repeated word in a string. My code is as follows: public class Word { private String toWord; private int Count; public Word(int count, String word){ toWord = word; Count = count; } public static void main(String args[]){ String str="my name is neo and my other name is also neo because I am neo"; String []str1=str.split(" "); Word w1=new Word(0,str1[0]); LinkedList<Word> list = new LinkedList<Word>(); list.add(w1); ListIterator itr = list.listIterator(); for(int i=1;i<str1.length;i++){ while(itr.hasNext()){ if(str1[i].equalsTO(????)); else list.add(new Word(0,str1[i])); } How do I compare the string from string array str1 to the string stored in the linked list and then how do i increase the respective count. I will then print the string with the highest count, I dont know how to do that either.

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• Concept of WNDCLASSEX, good programming habits and WndProc for system classes

  - by luiscubal

  I understand that the Windows API uses "classes", relying to the WNDCLASS/WNDCLASSEX structures. I have successfully gone through windows API Hello World applications and understand that this class is used by our own windows, but also by Windows core controls, such as "EDIT", "BUTTON", etc. I also understand that it is somehow related to WndProc(it allows me to define a function for it) Although I can find documentation about this class, I can't find anything explaining the concept. So far, the only thing I found about it was this: A Window Class has NOTHING to do with C++ classes. Which really doesn't help(it tells me what it isn't but doesn't tellme what it is). In fact, this only confuses me more, since I'd be tempted to associate WNDCLASSEX to C++ classes and think that "WNDCLASSEX" represents a control type . So, my first question is What is it? In second place, I understand that one can define a WndProc in a class. However, a window can also get messages from the child controls(or windows, or whatever they are called in the Windows API). How can this be? Finally, when is it a good programming practise to define a new class? Per application(for the main frame), per frame, one per control I define(if I create my own progress bar class, for example)? I know Java/Swing, C#/Windows.Form, C/GTK+ and C++/wxWidgets, so I'll probably understand comparisons with these toolkits.

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• CoInitialize fails in dll

  - by Quandary

  Question: I have the following program, which uses COM to use the Microsoft Speech API (SAPI) to take a text and output it as sound. Now it works fine as long as I have it in a .exe. When I load it as .dll, it fails. Why? I used dependencywalker, and saw the exe doesn't have MSVCR100D and ole32, so I loaded them like this: LoadLibraryA("MSVCR100D.DLL"); LoadLibraryA("ole32.dll"); but it didn't help... Any idea why ? #include <windows.h> #include <sapi.h> #include <cstdlib> int main(int argc, char* argv[]) { ISpVoice * pVoice = NULL; if (FAILED(::CoInitialize(NULL))) return FALSE; HRESULT hr = CoCreateInstance(CLSID_SpVoice, NULL, CLSCTX_ALL, IID_ISpVoice, (void **) &pVoice); if( SUCCEEDED( hr ) ) { hr = pVoice->Speak(L"Noobie was fragged by GSG9 Googlebot", 0, NULL); hr = pVoice->Speak(L"Test Test", 0, NULL); hr = pVoice->Speak(L"This sounds normal <pitch middle = '-10'/> but the pitch drops half way through", SPF_IS_XML, NULL ); pVoice->Release(); pVoice = NULL; } ::CoUninitialize(); return EXIT_SUCCESS; }

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• Content Management Systems for Adaptive Content [closed]

  - by andrewap

  Content management systems (CMS) allow us to easily maintain blogs, news sites, general websites, and so on. Many of them are designed to manage pages of content, and provide tools to organize and customize how that content is displayed on the web. However, as explained by Mark Boulton in his Adaptive Content Management article, and by Karen McGrane in her talk on Adapting Ourselves to Adaptive Content, we are increasingly delivering content not just to the web, but also to other platforms and channels. We need tools to manage pieces of content with meaningful metadata attached. Create once, publish everywhere. The main idea is to store content cleanly, without intertwining it with presentation markup specific to the web. Because pieces of content is compartmentalized semantically, it can easily adapt to fit in different platforms and channels. Hence, it's called adaptive content. Let's look at a quick example to compare: Say I manage news articles and events. To create a news article, I would tell the CMS the type of content I'm creating, and be asked to fill in a form with individual fields tailored to news articles (e.g. headline, subtitle, full text, short snippet, and images). — i.e. pieces of content With a traditional web publishing tool, I would probably have had to create a new page under News, and then type in and format the news article in a blank WYSIWYG text editor. — i.e. pages of content As you can see, the first design allows me to individually specify content in its smallest semantic unit. When I want to display or consume it, the system can easily provide the pieces I need. So here's my question: Is there a CMS that is designed specifically with adaptive content in mind, and that is decoupled with the presentation layer? Note: This is not a discussion about the best CMS, or which CMS I should use. I am asking whether a very specific type of tool — CMS designed for adaptive content — exists for developers to use.

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• Parallel version of loop not faster than serial version

  - by Il-Bhima

  I'm writing a program in C++ to perform a simulation of particular system. For each timestep, the biggest part of the execution is taking up by a single loop. Fortunately this is embarassingly parallel, so I decided to use Boost Threads to parallelize it (I'm running on a 2 core machine). I would expect at speedup close to 2 times the serial version, since there is no locking. However I am finding that there is no speedup at all. I implemented the parallel version of the loop as follows: Wake up the two threads (they are blocked on a barrier). Each thread then performs the following: Atomically fetch and increment a global counter. Retrieve the particle with that index. Perform the computation on that particle, storing the result in a separate array Wait on a job finished barrier The main thread waits on the job finished barrier. I used this approach since it should provide good load balancing (since each computation may take differing amounts of time). I am really curious as to what could possibly cause this slowdown. I always read that atomic variables are fast, but now I'm starting to wonder whether they have their performance costs. If anybody has some ideas what to look for or any hints I would really appreciate it. I've been bashing my head on it for a week, and profiling has not revealed much.

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• fgets in c don't return a portion of an string

  - by Marc

  Hi! I'm totally new in C, and I'm trying to do a little application that searches a string into a file, my problem is that I need to open a big file (more than 1GB) with just one line inside and fgets return me the entire file (I'm doing test with a 10KB file). actually this is my code: #include <stdio.h> #include <string.h> int main(int argc, char *argv[]) { char *search = argv[argc-1]; int retro = strlen(search); int pun = 0; int sortida; int limit = 10; char ara[20]; FILE *fp; if ((fp = fopen ("SEARCHFILE", "r")) == NULL){ sortida = -1; exit (1); } while(!feof(fp)){ if (fgets(ara, 20, fp) == NULL){ break; } //this must be a 20 bytes line, but it gets the entyre 10Kb file printf("%s",ara); } sortida = 1; if(fclose(fp) != 0){ sortida = -2; exit (1); } return 0; } What can I do to find an string into a file? I'v tried with GREP but it don't helps, because it returns the position:ENTIRE_STRING. I'm open to ideas. Thanks in advance!

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• how to implement a really efficient bitvector sorting in python

  - by xiao

  Hello guys! Actually this is an interesting topic from programming pearls, sorting 10 digits telephone numbers in a limited memory with an efficient algorithm. You can find the whole story here What I am interested in is just how fast the implementation could be in python. I have done a naive implementation with the module bitvector. The code is as following: from BitVector import BitVector import timeit import random import time import sys def sort(input_li): return sorted(input_li) def vec_sort(input_li): bv = BitVector( size = len(input_li) ) for i in input_li: bv[i] = 1 res_li = [] for i in range(len(bv)): if bv[i]: res_li.append(i) return res_li if __name__ == "__main__": test_data = range(int(sys.argv[1])) print 'test_data size is:', sys.argv[1] random.shuffle(test_data) start = time.time() sort(test_data) elapsed = (time.time() - start) print "sort function takes " + str(elapsed) start = time.time() vec_sort(test_data) elapsed = (time.time() - start) print "sort function takes " + str(elapsed) start = time.time() vec_sort(test_data) elapsed = (time.time() - start) print "vec_sort function takes " + str(elapsed) I have tested from array size 100 to 10,000,000 in my macbook(2GHz Intel Core 2 Duo 2GB SDRAM), the result is as following: test_data size is: 1000 sort function takes 0.000274896621704 vec_sort function takes 0.00383687019348 test_data size is: 10000 sort function takes 0.00380706787109 vec_sort function takes 0.0371489524841 test_data size is: 100000 sort function takes 0.0520560741425 vec_sort function takes 0.374383926392 test_data size is: 1000000 sort function takes 0.867373943329 vec_sort function takes 3.80475401878 test_data size is: 10000000 sort function takes 12.9204008579 vec_sort function takes 38.8053860664 What disappoints me is that even when the test_data size is 100,000,000, the sort function is still faster than vec_sort. Is there any way to accelerate the vec_sort function?

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