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  • flex data provider not working if XML has single node value or less

    - by Rees
    hello, i get this error when i retrieve an XML that only has 1 node (no repeating nodes) and i try to store in an ArrayCollection. -When I have MORE than 1 "name" nodes...i do NOT get an error. My test show that XMLListCollection does NOT work either. TypeError: Error #1034: Type Coercion failed: cannot convert "XXXXXX" to mx.collections.ArrayCollection. this error occurs as the line of code: myList= e.result.list.name; Why can't ArrayCollection work with a single node? I'm using this ArrayCollection as a dataprovider for a Component -is there an alternative I can use that will take BOTH single and repeating nodes as well as work as a dataprovider? Thanks in advance! code: [Bindable] private var myList:ArrayCollection= new ArrayCollection(); private function getList(e:Event):void{ var getStudyLoungesService:HTTPService = new HTTPService(); getStuffService.url = "website.com/asdf.php"; getStuffService.addEventListener(ResultEvent.RESULT, onGetList); getStuffService.send(); } private function onGetList(e:ResultEvent):void{ myList= e.result.list.name; }

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  • In Android GUI flickers when reading the properties file

    - by ManojValiveti
    Hi, I am getting the GUI flicker when reading a file properties and accordingly enabling/disabling checkbox and List value in listbox. when i remove this file reading code the GUI doesnt have flicker. I am reading the properties before creating the Preferences in OnCreate(). Attached the file write code below for reference.Please let us know is there any other way to read and update the preference staus. private void SetExtendConf(String key, String strValue) { mProperties = new Properties(); try { File file = new File(FILE_EXT); if(!file.exists()) file.createNewFile(); file.setWritable(true,false); FileInputStream fis = new FileInputStream(file); mProperties.load(fis); fis.close(); FileOutputStream stream = new FileOutputStream(file); Log.d(TAG, "Setting Values " + key + ":"+ strValue); mProperties.setProperty(key, strValue); mProperties.store(stream,"ext.conf"); stream.close(); } catch (IOException e) { Log.d(TAG, "Could not open properties file: " + GPS_FILE_EXT); } } -Manoj

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  • Reference to the Main Form whilst trying to Serialize objects in C#

    - by Paul Matthews
    I have a button on my main form which calls a method to serialize some objects to disk. I am trying to add these objects to an ArrayList and then serialize them using a BinaryFormatter and a FileStream. public void SerializeGAToDisk(string GenAlgName) { // Let's make a list that includes all the objects we // need to store a GA instance ArrayList GAContents = new ArrayList(); GAContents.Add(GenAlgInstances[GenAlgName]); // Structure and info for a GA GAContents.Add(RunningGAs[GenAlgName]); // There may be several running GA's using (FileStream fStream = new FileStream(GenAlgName + ".ga", FileMode.Create, FileAccess.Write, FileShare.None)) { BinaryFormatter binFormat = new BinaryFormatter(); binFormat.Serialize(fStream, GAContents); } } When running the above code I get the following exception: System.Runtime.Serialization.SerializationException was unhandled Message=Type 'WindowsFormsApplication1.Form1' in Assembly 'GeneticAlgApp, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' is not marked as serializable. So that means that somewhere in the objects I'm trying to save there must be a reference to the main form. The only possible references I can see are 3 delegates which all point to methods in the main form code. Do delegates get serialized as well? I can't seem to apply the [NonSerialized] attribute to them. Is there anything else I might be missing? Even better, is there a quick method to find the reference(s) that are causing the problem?

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  • Firefox proxy delima

    - by Mike L.
    Any idea why when using system proxy settings in firefox, it can not accept a proxy such as: user:[email protected]:port ??? IE will allow and connect to a proxy in this format. Not only does firefox not work, but it does not prompt for the password, nor attempt to make a connection to the proxy. Basically get a "proxy server not found" error. Anybody know a way around this? I am working on a proxy switching program for IE & Firefox, and I would like to use system-wide proxy settings. If I just store the server:port combination, firefox prompts for the password, as well as IE. Then they can be cached and it will not ask again. Maybe my only option is to programmatically cache the user/pass? Anybody know a way to do this? I am pretty sure IE stores them at HTTP basic authentication passwords and I can add them with AddCredential. After saving a password for a proxy in firefox, it shows up in saved passwords in a format like "moz-proxy://server:port" anybody know how to programmatically add a saved password to firefox? Thanks

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  • How to iterate JPA collections in Google App engine

    - by palto
    Hi I use Google App Engine with datanucleus and JPA. I'm having a real hard time grasping how I'm supposed to read stuff from data store and pass it to JSP. If I load a list of POJOs with entitymanager and pass it to JSP, it crashes to org.datanucleus.exceptions.NucleusUserException: Object Manager has been closed. I understand why this is happening. Obviously because I fetch the list, close the entity manager and pass it to JSP, at which point it will fail because the list is lazy. How do I make the list NOT lazy without resorting to hacks like calling size() or something like that? Here is what I'm trying to do: @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { req.setAttribute("parties", getParties()); RequestDispatcher dispatcher = getServletContext().getRequestDispatcher("/WEB-INF/parties.jsp"); dispatcher.forward(req, resp); } private List<Party> getParties(){ EntityManager em = entityManagerProvider.get(); try{ Query query = em.createQuery("SELECT p FROM Party p"); return query.getResultList(); }finally{ em.close(); } }

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  • Trying to make a plugin system in C++

    - by Pirate for Profit
    I'm making a task-based program that needs to have plugins. Tasks need to have properties which can be easily edited, I think this can be done with Qt's Meta-Object Compiler reflection capabilities (I could be wrong, but I should be able to stick this in a QtPropertyBrowser?) So here's the base: class Task : public QObject { Q_OBJECT public: explicit Task(QObject *parent = 0) : QObject(parent){} virtual void run() = 0; signals: void taskFinished(bool success = true); } Then a plugin might have this task: class PrinterTask : public Task { Q_OBJECT public: explicit PrinterTask(QObject *parent = 0) : Task(parent) {} void run() { Printer::getInstance()->Print(this->getData()); // fictional emit taskFinished(true); } inline const QString &getData() const; inline void setData(QString data); Q_PROPERTY(QString data READ getData WRITE setData) // for reflection } In a nutshell, here's what I want to do: // load plugin // find all the Tasks interface implementations in it // have user able to choose a Task and edit its specific Q_PROPERTY's // run the TASK It's important that one .dll has multiple tasks, because I want them to be associated by their module. For instance, "FileTasks.dll" could have tasks for deleting files, making files, etc. The only problem with Qt's plugin setup is I want to store X amount of Tasks in one .dll module. As far as I can tell, you can only load one interface per plugin (I could be wrong?). If so, the only possible way to do accomplish what I want is to create a FactoryInterface with string based keys which return the objects (as in Qt's Plug-And-Paint example), which is a terrible boilerplate that I would like to avoid. Anyone know a cleaner C++ plugin architecture than Qt's to do what I want? Also, am I safely assuming Qt's reflection capabilities will do what I want (i.e. able to edit an unknown dynamically loaded tasks' properties with the QtPropertyBrowser before dispatching)?

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  • Optimizing T-SQL where an array would be nice

    - by Polatrite
    Alright, first you'll need to grab a barf bag. I've been tasked with optimizing several old stored procedures in our database. This SP does the following: 1) cursor loops through a series of "buildings" 2) cursor loops through a week, Sunday-Saturday 3) has a huge set of IF blocks that are responsible for counting how many Objects of what Types are present in a given building Essentially what you'll see in this code block is that, if there are 5 objects of type #2, it will increment @Type_2_Objects_5 by 1. IF @Number_Type_1_Objects = 0 BEGIN SET @Type_1_Objects_0 = @Type_1_Objects_0 + 1 END IF @Number_Type_1_Objects = 1 BEGIN SET @Type_1_Objects_1 = @Type_1_Objects_1 + 1 END IF @Number_Type_1_Objects = 2 BEGIN SET @Type_1_Objects_2 = @Type_1_Objects_2 + 1 END IF @Number_Type_1_Objects = 3 BEGIN SET @Type_1_Objects_3 = @Type_1_Objects_3 + 1 END [... Objects_4 through Objects_20 for Type_1] IF @Number_Type_2_Objects = 0 BEGIN SET @Type_2_Objects_0 = @Type_2_Objects_0 + 1 END IF @Number_Type_2_Objects = 1 BEGIN SET @Type_2_Objects_1 = @Type_2_Objects_1 + 1 END IF @Number_Type_2_Objects = 2 BEGIN SET @Type_2_Objects_2 = @Type_2_Objects_2 + 1 END IF @Number_Type_2_Objects = 3 BEGIN SET @Type_2_Objects_3 = @Type_2_Objects_3 + 1 END [... Objects_4 through Objects_20 for Type_2] In addition to being extremely hacky (and limited to a quantity of 20 objects), it seems like a terrible way of handling this. In a traditional language, this could easily be solved with a 2-dimensional array... objects[type][quantity] += 1; I'm a T-SQL novice, but since writing stored procedures often uses a lot of temporary tables (which could essentially be a 2-dimensional array) I was wondering if someone could illuminate a better way of handling a situation like this with two dynamic pieces of data to store. Requested in comments: The columns are simply Number_Type_1_Objects, Number_Type_2_Objects, Number_Type_3_Objects, Number_Type_4_Objects, Number_Type_5_Objects, and CurrentDateTime. Each row in the table represents 5 minutes. The expected output is to figure out what percentage of time a given quantity of objects is present throughout each day. Sunday - Object Type 1 0 objects - 69 rows, 5:45, 34.85% 1 object - 85 rows, 7:05, 42.93% 2 objects - 44 rows, 3:40, 22.22% On Sunday, there were 0 objects of type 1 for 34.85% of the day. There was 1 object for 42.93% of the day, and 2 objects for 22.22% of the day. Repeat for each object type.

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  • Android - Parsing XML with XPath

    - by Ruben Deig Ramos
    First of all, thanks to all the people who's going to spend a little time on this question. Second, sorry for my english (not my first language! :D). Well, here is my problem. I'm learning Android and I'm making an app which uses a XML file to store some info. I have no problem creating the file, but trying to read de XML tags with XPath (DOM, XMLPullParser, etc. only gave me problems) I've been able to read, at least, the first one. Let's see the code. Here is the XML file the app generates: <dispositivo> <id>111</id> <nombre>Name</nombre> <intervalo>300</intervalo> </dispositivo> And here is the function which reads the XML file: private void leerXML() { try { XPathFactory factory=XPathFactory.newInstance(); XPath xPath=factory.newXPath(); // Introducimos XML en memoria File xmlDocument = new File("/data/data/com.example.gps/files/devloc_cfg.xml"); InputSource inputSource = new InputSource(new FileInputStream(xmlDocument)); // Definimos expresiones para encontrar valor. XPathExpression tag_id = xPath.compile("/dispositivo/id"); String valor_id = tag_id.evaluate(inputSource); id=valor_id; XPathExpression tag_nombre = xPath.compile("/dispositivo/nombre"); String valor_nombre = tag_nombre.evaluate(inputSource); nombre=valor_nombre; } catch (Exception e) { e.printStackTrace(); } } The app gets correctly the id value and shows it on the screen ("id" and "nombre" variables are assigned to a TextView each one), but the "nombre" is not working. What should I change? :) Thanks for all your time and help. This site is quite helpful! PD: I've been searching for a response on the whole site but didn't found any.

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  • Performing a SVD on tweets. Memory problem

    - by plotti
    I have generated a huge csv file as an output from my pos tagging and stemming. It looks like this: word1, word2, word3, ..., word14400 person1 1 2 0 1 person2 0 0 1 0 ... person650 It contains the word counts for each person. Like this I am getting characteristic vectors for each person. I want to run a SVD on this beast, but it seems the matrix is too big to be held in memory to perform the operation. My quesion is: should i reduce the column size by removing words which have a column sum of for example 1, which means that they have been used only once. Do I bias the data too much with this attempt? I tried the rapidminer attempt, by loading the csv into the db. and then sequentially reading it in with batches for processing, like rapidminer proposes. But Mysql can't store that many columns in a table. If i transpose the data, and then retranspose it on import it also takes ages.... -- So in general I am asking for advice how to perform a svd on such a corpus.

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  • Django Aggregation Across Reverse Relationship

    - by Tom
    Given these two models: class Profile(models.Model): user = models.ForeignKey(User, unique=True, verbose_name=_('user')) about = models.TextField(_('about'), blank=True) zip = models.CharField(max_length=10, verbose_name='zip code', blank=True) website = models.URLField(_('website'), blank=True, verify_exists=False) class ProfileView(models.Model): profile = models.ForeignKey(Profile) viewer = models.ForeignKey(User, blank=True, null=True) created = models.DateTimeField(auto_now_add=True) I want to get all profiles sorted by total views. I can get a list of profile ids sorted by total views with: ProfileView.objects.values('profile').annotate(Count('profile')).order_by('-profile__count') But that's just a dictionary of profile ids, which means I then have to loop over it and put together a list of profile objects. Which is a number of additional queries and still doesn't result in a QuerySet. At that point, I might as well drop to raw SQL. Before I do, is there a way to do this from the Profile model? ProfileViews are related via a ForeignKey field, but it's not as though the Profile model knows that, so I'm not sure how to tie the two together. As an aside, I realize I could just store views as a property on the Profile model and that may turn out to be what I do here, but I'm still interested in learning how to better use the Aggregation functions.

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  • Load some data from database and hide it somewhere in a web page

    - by kwokwai
    Hi all, I am trying to load some data (which may be up to a few thousands words) from the database, and store the data somewhere in a html web page for comparing the data input by users. I am thinking to load the data to a Textarea under Div tag and hide the the data: <Div id="reference" style="Display:none;"> <textarea rows="2" cols="20" id="database"> html, htm, php, asp, jsp, aspx, ctp, thtml, xml, xsl... </textarea> </Div> <table border=0 width="100%"> <tr> <td>Username</td> <td> <div id="username"> <input type="text" name="data" id="data"> </div> </td> </tr> </table> <script> $(document).ready(function(){ //comparing the data loaded from database with the user's input if($("#data").val()==$("#database").val()) {alert("error");} }); </script> I am not sure if this is the best way to do it, so could you give me some advice and suggest your methods please.

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  • Java - Removing duplicates in an ArrayList

    - by Will
    I'm working on a program that uses an ArrayList to store Strings. The program prompts the user with a menu and allows the user to choose an operation to perform. Such operations are adding Strings to the List, printing the entries etc. What I want to be able to do is create a method called removeDuplicates().This method will search the ArrayList and remove any duplicated values. I want to leave one instance of the duplicated value(s) within the list. I also want this method to return the total number of duplicates removed. I've been trying to use nested loops to accomplish this but I've been running into trouble because when entries get deleted, the indexing of the ArrayList gets altered and things don't work as they should. I know conceptually what I need to do but I'm having trouble implementing this idea in code. Here is some pseudo code: start with first entry; check each subsequent entry in the list and see if it matches the first entry; remove each subsequent entry in the list that matches the first entry; after all entries have been examined, move on to the second entry; check each entry in the list and see if it matches the second entry; remove each entry in the list that matches the second entry; repeat for entry in the list Here's the code I have so far: public int removeDuplicates() { int duplicates = 0; for ( int i = 0; i < strings.size(); i++ ) { for ( int j = 0; j < strings.size(); j++ ) { if ( i == j ) { // i & j refer to same entry so do nothing } else if ( strings.get( j ).equals( strings.get( i ) ) ) { strings.remove( j ); duplicates++; } } } return duplicates; }

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  • How to inject php code from database into php script ?

    - by luxquarta
    I want to store php code inside my database and then use it into my script. class A { public function getName() { return "lux"; } } // instantiates a new A $a = new A(); Inside my database there is data like "hello {$a->getName()}, how are you ?" In my php code I load the data into a variable $string $string = load_data_from_db(); echo $string; // echoes hello {$a->getName()}, how are you ? So now $string contains "hello {$a-getName()}, how are you ?" {$a-getName()} still being un-interpretated Question: I can't find how to write the rest of the code so that {$a-getName()} gets interpretated "into hello lux, how are you". Can someone help ? $new_string = ?????? echo $new_string; //echoes hello lux, how are you ? Is there a solution with eval() ? (please no debate about evil eval ;)) Or any other solution ?

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  • How to systematically generate images from data?

    - by adamvickers
    I work for a performing arts nonprofit. We have seating charts for each of the theaters we work with; each seating chart shows the number of sections, the shape of each section, and the number of rows in each section. We'd like to create dynamic seating charts based on this info. We'd like them to look/feel kinda like this: http://www.fansnap.com/tickets/177754-on. But the tricky part is we'd like to be able to store all the info about each theater (the section names, shape/size of each section, and number of rows in each section) as data and then build a system that reads this data and uses it to create a dynamic map. I'm a life-long web developer, but I don't have have any experience with a difficult graphics problem like this. I realize it's a complex problem and I don't expect anyone to give me a complete answer here, but I would love direction on where I should be looking for more info. Is what I'm describing possible? Does this sort of technique have a name? Where can I learn more about how to accomplish this? What software should I use? Any info would be helpful.

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  • Dependent Dropdowns (Linked Selects) with single class (no other selectors)

    - by AJ
    I am trying to create multiple dependent dropdowns (selects) with a unique way. I want to restrict the use of selectors and want to achieve this by using a single class selectors on all SELECTs; by figuring out the SELECT that was changed by its index. Hence, the SELECT[i] that changed will change the SELECT[i+1] only (and not the previous ones like SELECT[i-1]). For html like this: <select class="someclass"> <option value="volvo">Volvo</option> <option value="saab">Saab</option> <option value="mercedes">Mercedes</option> <option value="audi">Audi</option> </select> <select class="someclass"> </select> <select class="someclass"> </select> where the SELECTs other than the first one will get something via AJAX. I see that the following Javascript gives me correct value of the correct SELECT and the value of i also corresponds to the correct SELECT. $(function() { $(".someclass").each(function(i) { $(this).change(function(x) { alert($(this).val() + i); }); }); }); Please note that I really want the minimum selector approach. I just cannot wrap my head around on how to approach this. Should I use Arrays? Like store all the SELECTS in an Array first and then select those? I believe that since the above code already passes the index i, there should be a way without Arrays also. Thanks a bunch. AJ

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  • Incrementing value by one over a lot of rows

    - by Andy Gee
    Edit: I think the answer to my question lies in the ability to set user defined variables in MySQL through PHP - the answer by Multifarious has pointed me in this direction Currently I have a script to cycle over 10M records, it's very slow and it goes like this: I first get a block of 1000 results in an array similar to this: $matches[] = array('quality_rank'=>46732, 'db_id'=>5532); $matches[] = array('quality_rank'=>12324, 'db_id'=>1234); $matches[] = array('quality_rank'=>45235, 'db_id'=>8345); $matches[] = array('quality_rank'=>75543, 'db_id'=>2562); I then cycle through them one by one and update the record $mult = count($matches)*2; foreach($matches as $m) { $rank++; $score = (($m[quality_rank] + $rank)/($mult))*100; $s = "UPDATE `packages_sorted` SET `price_rank` = '".$rank."', `deal_score` = '".$score."' WHERE `db_id` = '".$m[db_id]."' LIMIT 1"; } It seems like this is a very slow way of doing it but I can't find another way to increment the field price_rank by one each time. Can anyone suggest a better method. Note: Although I wouldn't usually store this kind of value in a database I really do need on this occasion for comparison search queries later on in the project. Any help would be kindly appreciated :)

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  • C++ Storing variables and inheritance

    - by Kaa
    Hello Everyone, Here is my situation: I have an event driven system, where all my handlers are derived from IHandler class, and implement an onEvent(const Event &event) method. Now, Event is a base class for all events and contains only the enumerated event type. All actual events are derived from it, including the EventKey event, which has 2 fields: (uchar) keyCode and (bool)isDown. Here's the interesting part: I generate an EventKey event using the following syntax: Event evt = EventKey(15, true); and I ship it to the handlers: EventDispatch::sendEvent(evt); // void EventDispatch::sendEvent(const Event &event); (EventDispatch contains a linked list of IHandlers and calls their onEvent(const Event &event) method with the parameter containing the sent event. Now the actual question: Say I want my handlers to poll the events in a queue of type Event, how do I do that? x Dynamic pointers with reference counting sound like too big of a solution. x Making copies is more difficult than it sounds, since I'm only receiving a reference to a base type, therefore each time I would need to check the type of event, upcast to EventKey and then make a copy to store in a queue. Sounds like the only solution - but is unpleasant since I would need to know every single type of event and would have to check that for every event received - sounds like a bad plan. x I could allocate the events dynamically and then send around pointers to those events, enqueue them in the array if wanted - but other than having reference counting - how would I be able to keep track of that memory? Do you know any way to implement a very light reference counter that wouldn't interfere with the user? What do you think would be a good solution to this design? I thank everyone in advance for your time. Sincerely, Kaa

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  • Multithreaded linked list traversal

    - by Rob Bryce
    Given a (doubly) linked list of objects (C++), I have an operation that I would like multithread, to perform on each object. The cost of the operation is not uniform for each object. The linked list is the preferred storage for this set of objects for a variety of reasons. The 1st element in each object is the pointer to the next object; the 2nd element is the previous object in the list. I have solved the problem by building an array of nodes, and applying OpenMP. This gave decent performance. I then switched to my own threading routines (based off Windows primitives) and by using InterlockedIncrement() (acting on the index into the array), I can achieve higher overall CPU utilization and faster through-put. Essentially, the threads work by "leap-frog'ing" along the elements. My next approach to optimization is to try to eliminate creating/reusing the array of elements in my linked list. However, I'd like to continue with this "leap-frog" approach and somehow use some nonexistent routine that could be called "InterlockedCompareDereference" - to atomically compare against NULL (end of list) and conditionally dereference & store, returning the dereferenced value. I don't think InterlockedCompareExchangePointer() will work since I cannot atomically dereference the pointer and call this Interlocked() method. I've done some reading and others are suggesting critical sections or spin-locks. Critical sections seem heavy-weight here. I'm tempted to try spin-locks but I thought I'd first pose the question here and ask what other people are doing. I'm not convinced that the InterlockedCompareExchangePointer() method itself could be used like a spin-lock. Then one also has to consider acquire/release/fence semantics... Ideas? Thanks!

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  • Recursive powerof-function, see if you can solve it

    - by Jonas B
    First of all, this is not schoolwork - just my curiousity as I for some reason can't get my head around it and solve it. I come up with these stupid things all the time and it annoys the hell out of me when I cant solve them. Code example is in C# but solution doesn't have to be in any particular programming-language. long powerofnum(short num, long powerof) { return powerofnum2(num, powerof, powerof); } long powerofnum2(short num, long powerof, long holder) { if (num == 1) return powerof; else { return powerof = powerofnum2(num - 1, holder * powerof, holder); } } As you can see I have two methods. I call for powerofnum(value, powerofvalue) which then calls the next method with the powerofvalue also in a third parameter as a placeholder so it remembers the original powerof value through the recursion. What I want to accomplish is to do this with only one method. I know I could just declare a variable in the first method with the powerof value to remember it and then iterate from 0 to value of num. But as this is a theoretical question I want it done recursively. I could also in the first method just take a third parameter called whatever to store the value just like I do in the second method that is called by the first, but that looks really stupid. Why should you have to write what seems like the same parameter twice? Rules explained in short: no iteration scope-specific variables only only one method Anyhow, I'd appreciate a clean solution. Good luck :)

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  • Char C question about encoding signed/unsigned.

    - by drigoSkalWalker
    Hi guys. I read that C not define if a char is signed or unsigned, and in GCC page this says that it can be signed on x86 and unsigned in PowerPPC and ARM. Okey, I'm writing a program with GLIB that define char as gchar (not more than it, only a way for standardization). My question is, what about UTF-8? It use more than an block of memory? Say that I have a variable unsigned char *string = "My string with UTF8 enconding ~ çã"; See, if I declare my variable as unsigned I will have only 127 values (so my program will to store more blocks of mem) or the UTF-8 change to negative too? Sorry if I can't explain it correctly, but I think that i is a bit complex. NOTE: Thanks for all answer I don't understand how it is interpreted normally. I think that like ascii, if I have a signed and unsigned char on my program, the strings have diferently values, and it leads to confuse, imagine it in utf8 so.

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  • Uniquing with Existing Core Data Entities

    - by warrenm
    I'm using Core Data to store a lot (1000s) of items. A pair of properties on each item are used to determine uniqueness, so when a new item comes in, I compare it against the existing items before inserting it. Since the incoming data is in the form of an RSS feed, there are often many duplicates, and the cost of the uniquing step is O(N^2), which has become significant. Right now, I create a set of existing items before iterating over the list of (possible) new items. My theory is that on the first iteration, all the items will be faulted in, and assuming we aren't pressed for memory, most of those items will remain resident over the course of the iteration. I see my options thusly: Use string comparison for uniquing, iterating over all "new" items and comparing to all existing items (Current approach) Use a predicate to filter the set of existing items against the properties of the "new" items. Use a predicate with Core Data to determine uniqueness of each "new" item (without retrieving the set of existing items). Is option 3 likely to be faster than my current approach? Do you know of a better way?

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  • In Rails, a Sweeper isn't getting called in a Model-only setup

    - by charliepark
    I'm working on a Rails app, where I'm using page caching to store static html output. The caching works fine. I'm having trouble expiring the caches, though. I believe my problem is, in part, because I'm not expiring the cache from my controller. All of the actions necessary for this are being handled within the model. This seems like it should be doable, but all of the references to Model-based cache expiration that I'm finding seem to be out of date, or are otherwise not working. In my environment.rb file, I'm calling config.load_paths += %W( #{RAILS_ROOT}/app/sweepers ) And I have, in the /sweepers folder, a LinkSweeper file: class LinkSweeper < ActionController::Caching::Sweeper observe Link def after_update(link) clear_links_cache(link) end def clear_links_cache(link) # expire_page :controller => 'links', :action => 'show', :md5 => link.md5 expire_page '/l/'+ link.md5 + '.html' end end So ... why isn't it deleting the cached page when I update the model? (Process: using script/console, I'm selecting items from the database and saving them, but their corresponding pages aren't deleting from the cache), and I'm also calling the specific method in the Link model that would normally invoke the sweeper. Neither works. If it matters, the cached file is an md5 hash off a key value in the Links table. The cached page is getting stored as something like /l/45ed4aade64d427...99919cba2bd90f.html. Essentially, it seems as though the Sweeper isn't actually observing the Link. I also read (here) that it might be possible to simply add the sweeper to config.active_record.observers in environment.rb, but that didn't seem to do it (and I wasn't sure if the load_path of app/sweepers in environment.rb obviated that).

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  • Should I use a binary or a text file for storing protobuf messages?

    - by nbolton
    Using Google protobuf, I am saving my serialized messaged data to a file - in each file there are several messages. We have both C++ and Python versions of the code, so I need to use protobuf functions that are available in both languages. I have experimented with using SerializeToArray and SerializeAsString and there seems to be the following unfortunate conditions: SerializeToArray: As suggested in one answer, the best way to use this is to prefix each message with it's data size. This would work great for C++, but in Python it doesn't look like this is possible - am I wrong? SerializeAsString: This generates a serialized string equivalent to it's binary counterpart - which I can save to a file, but what happens if one of the characters in the serialization result is \n - how do we find line endings, or the ending of messages for that matter? Update: Please allow me to rephrase slightly. As I understand it, I cannot write binary data in C++ because then our Python application cannot read the data, since it can only parse string serialized messages. Should I then instead use SerializeAsString in both C++ and Python? If yes, then is it best practice to store such data in a text file rather than a binary file? My gut feeling is binary, but as you can see this doesn't look like an option.

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  • How to treat Base* pointer as Derived<T>* pointer?

    - by dehmann
    I would like to store pointers to a Base class in a vector, but then use them as function arguments where they act as a specific class, see here: #include <iostream> #include <vector> class Base {}; template<class T> class Derived : public Base {}; void Foo(Derived<int>* d) { std::cerr << "Processing int" << std::endl; } void Foo(Derived<double>* d) { std::cerr << "Processing double" << std::endl; } int main() { std::vector<Base*> vec; vec.push_back(new Derived<int>()); vec.push_back(new Derived<double>()); Foo(vec[0]); Foo(vec[1]); delete vec[0]; delete vec[1]; return 0; } This doesn't compile: error: call of overloaded 'Foo(Base*&)' is ambiguous Is it possible to make it work? I need to process the elements of the vector differently, according to their int, double, etc. types.

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  • How to build a windows/web application that stores data locally and sync's with remote database?

    - by Jason
    Hello, I am needing to build an application that stores data locally and then synchronizes with a remote MS SQL database. I am not sure how to go about doing this. Enter data offline on a form and store the data. Synchronize the data with a remote MS SQL database when online. There will be many users who enter data offline, the local database on each pc needs to update when online and grab the 30 most recent records for use offline. Example: Each day users will enter data on their "form". The users will be offline. The users will return to the office and need to sync with the "online" database. The next morning the users will need to sync with the online database before going offline. They will need to have offline access to the 30 most recent records. (They will use the 30 records for charting/graphing while they are offline) I am very new to building apps. I have VS 2010. I am wondering where to start? What language to use? Is there a "framework" for doing this type of app? Any info or suggestions would be greatly appreciated. Thanks!

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