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• What is the difference between the * and the & operators in c programming?

  - by Wesley

  I am just making sure I understand this concept correctly. With the * operator, I make a new variable, which is allocated a place in memory. So as to not unnecessarily duplicate variables and their values, the & operator is used in passing values to methods and such and it actually points to the original instance of the variable, as opposed to making new copies...Is that right? It is obviously a shallow understanding, but I just want to make sure I am not getting them mixed up. Thanks!

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• Using ManagementClass.Getinstances() from IronPython

  - by Leo Bontemps

  I have an IronPython script that looks for current running processes using WMI. The code looks like this: import clr clr.AddReference('System.Management') from System.Management import ManagementClass from System import Array mc = ManagementClass('Win32_Processes') procs = mc.GetInstances() That last line where I call the GetInstances() method raises the following error: Traceback (most recent call first): File "<stdin>", line 1, in <module> SystemError: Not Found I am not understanding what's not being found?!? I believe that I may need to pass an instance of ManagementOperationObserver and of EnumerationOptions to GetInstance() however, I don't understand why that is, since the method with the signature Getinstance() is available in ManagementClass.

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• NHibernate: References still being eagerly selected after specifying AddJoin

  - by cbp

  I have a query which is something like this: Session.CreateSQLQuery( @"SELECT f.*, b.*, z.* FROM Foo f LEFT OUTER JOIN Bar b ON b.Id = f.BarId LEFT OUTER JOIN Zar z ON z.Id = b.ZarId" ) .AddEntity("f", typeof(Foo)) .AddJoin("b", "f.BarId") .AddJoin("z", "f.ZarId") .List<Foo>(); The problem is that I am still getting hundreds of SELECT requests made to the Zar table, even though I have specified that Zar should be joined. As far as I am aware the only relationship is Foo-Bar-Zar, i.e. the reference to Zar is not occurring anywhere else. Is my understanding of AddJoin correct? What could be going wrong? List item

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• Java how does Key Event Handling Mechanism(KeyListeners notified) work ?

  - by Carbonizer

  How does application/JVM know which classes if implemented key handling interfaces ? Does it use java Reflections or does it check all the classes for methods ? How can a application or executing JVM understanding to deliver the user event or call the specific methods on a class that implemented the keylistener interface. Does it look at all the classes if those methods are implemented or how does it know which classes implmented keylistener interface ? If you dont implement the keylistener Interface for a class but still implmentation all its methods. Do the class still process the user event occurred ?

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• Const-Qualification of Main's Parameters in C++

  - by pt2cv

  The C++ standard mandates that all conforming implementations support the following two signatures for main: int main(); int main(int, char*[]); In case of the latter signature, would the addition of (top-level) const-ness break any language rules? For example: int main(const int argc, char** const argv); From my understanding, top-level const qualification doesn't affect the function's signature hash, so it should be legal as far as the specification is concerned. Also, did anyone ever encounter an implementation which rejected this type of modification?

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• Question marks in Java generics.

  - by gnucom

  I tried to make sure this wasn't a duplicate post, sorry if I was blind. This is a small snippet of code taken from some of the examples that accompany the Stanford Parser. I've been developing in Java for about 4 years, but have never had a very strong understanding of what this style of code is supposed to indicate. List<? extends HasWord> wordList = toke.tokenize(); I'm not worried about the details of the code. What I'm confusing about is what exactly the generic expression is supposed to convey, in English. Can someone explain this to me? Thanks!

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• How is push()ing and pop()ping defined?

  - by Helper Method

  I know how the push() and pop() methods in a typical implementation of a Queue/Linked List work but what I do want to know is what you actually define as a push or a pop? When can you name a method push()/pop()? What makes the insert()/add() method in a typical Tree implementation not a push()? My understanding is that push()ing means putting something to a position some special pointer is pointing to, and pop()ping an element means putting some object away some pointer is pointing to, but it doesn't seem to be clearly defined. Or does the naming matter at all?

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• Light effect with image magick

  - by GuilhermeA

  Hello, I'm using ImageMagick to resize an image to a smaller size gif. In this process I'm trying to give the image a light effect, not a side-light, just like a shiny look all over. Not a good comparison but for a better understanding think of an image seen in a old screen or an image seen in glossy monitor - I'm trying to enhance the image the closest to this point. An important point is that I can't make a image-to-image treatment, it must be something that I can use in all the images. I know ImageMagick is a powerful tool, and can certainly do something for my images! Many thanks!

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• antlr: Best practice to integrate generated parser into the system

  - by green

  Here is the background, I am trying to create a DSL to allow customer write simple scripts to query into our mongodb based database. I choose antlr to implement the DSL. From my understanding (and pls let me know if it's not correct) there are 2 approaches to integrate antlr generated parser into the system: Embed code into the grammar file so that the generated parser could be used directly to make query to the database and return result in a certain format (e.g. json encoded) Keep the parser purely a parser, after feed the DSL file to it, and construct the query in another class by retrieving the AST from generated parser class So antlrers, which one do you think is the way I as an antlr newbie should go? Can you list the pros and cos of each approach, or you have other way to recommend?

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• How the websocket bi-directional concept work?

  - by GMsoF

  I think the main difference between websocket and http streaming (I am not refering to polling and long polling) is websocket allows bi-directional communication which is similar to usual raw socket programming. (above is my understanding, could be wrong, feel free to correct me.) My question is how the web client (browser) continue to send another request in the already-opened websocket? Usual http request will treat another request as new socket connection, but websocket does not, that is why I am confused, how it achieve that? It should be handled in Server side or Client (browser) side?

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• How to find hidden properties/methods in Javascript objects?

  - by ramanujan

  I would like to automatically determine all of the properties (including the hidden ones) in a given Javascript object, via a generalization of this function: function keys(obj) { var ll = []; for(var pp in obj) { ll.push(pp); } return ll; } This works for user defined objects but fails for many builtins: repl> keys({"a":10,"b":2}); // ["a","b"] repl> keys(Math) // returns nothing! Basically, I'd like to write equivalents of Python's dir() and help(), which are really useful in exploring new objects. My understanding is that only the builtin objects have hidden properties (user code evidently can't set the "enumerable" property till HTML5), so one possibility is to simply hardcode the properties of Math, String, etc. into a dir() equivalent (using the lists such as those here). But is there a better way?

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• Why should i POST data rather then GET?

  - by acidzombie24

  I know you dont want to POST a form with a username and password where anyone could use the history to see or situations where repeat actions may not be desired (refreshing a page = adding an item to a cart may not be desired). So i have an understanding when i may want to use one over the other. But i could always have the server redirect the url after a get to get around the cart problem and maybe most of my forms will work perfectly fine with get. WHY should i use POST over get? I dont understand the benefits of one over the other. I do notice post doesnt add data to the history/url and will warn you about refreshing the page but those are the only two differences i know of. Why as a developer might i want to use one over the other?

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• C++ pointer, Beginner Question...

  - by BobAlmond

  Hi there, just want to ask a beginner question... here, I made some code, for understanding the concept/basic of pointer: int a=1; int *b=&a; int **c = &b; int ***d = &c; cout << &*(&*d) << endl; can someone explain to me, why the &*(&d) return address of "c" instead of address of "b"? I've also tried code like &(&(&(&*(&*d)))), but it keep return address of "c" Thanks a lot :)

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• Encog 3.0 backpropagation

  - by Mohamed Shouman

  I have a question...I am using Encog framework to train a network using BP. I am training the network using images that has some object say a cat, telling the network which images are cats and which are not. Bellow are my Neural Network results actual=0.1545868370551181 ideal=0.0,actual=0.797896306829758 ideal=1.0,actual=0.1545868370551181 ideal=0.0,actual=0.797896306829758 ideal=1.0 It is my understanding that since different pictures are presented to network some look like cat for example then they should have higher percentage...but i keep getting same percentage for any pic that has a cat which is 0.79 and for other pics i get 0.15...how can i solve this issue!, what is the intuition behind whats going on! Many thanks

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• HTML block nested in PHP if statement - is this considered bad practice?

  - by JYelton

  Consider the following example: <table> <tr> <td>Row One</td> </tr> <?php if ($rowtwo) { ?> <tr> <td>Row Two</td> </tr> <?php } ?> </table> If $rowtwo is true, the second row is output, otherwise it is skipped. The code works as desired, however I am evaluating Netbeans (7 beta) as a PHP IDE (instead of just using a text editor). Netbeans flags the code with an error: Misplaced non-space characters insided [sic] a table. Should I consider an alternate way of writing this code, or is Netbeans incapable of understanding this flow control wrapper for HTML output?

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• jquery - how is multiple selection working in this example?

  - by hatorade

  The relevant snippet of HTML: <span class="a"> <div class="fieldname">Question 1</div> <input type="text" value="" name="q1" /> </span> The relevant jQuery: $.each($('.a'), function(){ $thisField = $('.fieldname', $(this)); }); What exactly is being set to $thisField? If my understanding of multiple selectors in jQuery is correct, it should be grabbing the outer <span> element AND the inner <div> element. But for some reason, if I use $thisField.prepend("hi"); it ends up putting hi right before the text Question 1, but not before <div>. I thought multiple selectors would grab both elements, and that prepend() adds hi to the beginning of BOTH elements, not just the <div>

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• Android sql creating database once

  - by semajhan

  One thing i'm not understanding is how to create the database and data just once in an android application. I extend SQLiteOpenHelper and use a DataHelper class that to manipulate data. Now, I have addEvent() and updateEvent() within the DataHelper class. I create an instance of DataHelper in my Activity and addEvent() a couple of times to insert data. Well, now I don't know how to just do that once. If I restart the app, its just going to "addEvent()" again and so the data is being reset every time. Sorry for the probably really REALLY noob question. The only solution I found was not using the DataHelper class and just adding data "manually" within the onCreate() method in SQLiteOpenHelper.

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• Rails 3 refactoring issue

  - by Craig

  The following view code generates a series of links with totals (as expected): <% @jobs.group_by(&:employer_name).sort.each do |employer, jobs| %> <%= link_to employer, jobs_path() %> <%= "(#{jobs.length})" %> <% end %> However, when I refactor the view's code and move the logic to a helper, the code doesn't work as expect. view: <%= employer_filter(@jobs_clone) %> helper: def employer_filter(jobs) jobs.group_by(&:employer_name).sort.each do |employer,jobs| link_to employer, jobs_path() end end The following output is generated: <Job:0x10342e628>#<Job:0x10342e588>#<Job:0x10342e2e0>Employer A#<Job:0x10342e1c8>Employer B#<Job:0x10342e0d8>Employer C#<Job:0x10342ded0>Employer D# What am I not understanding? At first blush, the code seems to be equivalent.

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• C read part of file into cache

  - by Pete Jodo

  I have to do a program (for Linux) where there's an extremely large index file and I have to search and interpret the data from the file. Now the catch is, I'm only allowed to have x-bytes of the file cached at any time (determined by argument) so I have to remove certain data from the cache if it's not what I'm looking for. If my understanding is correct, fopen (r) doesn't put anything in the cache, only when I call getc or fread(specifying size) does it get cached. So my question is, lets say I use fread and read 100 bytes but after checking it, only 20 of the 100 bytes contains the data I need; how would I remove the useless 80 bytes from cache (or overwrite it) in order to read more from the file.

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• Facebook Connect in iPhone app: Able to have two sessions?

  - by TheGambler

  Does anyone know if you are able to have two sessions save in one iphone app? I don't mean two sessions active. I want to be able to let someone switch between facebook accounts in my app without having to logout and back in. To my understanding a sessions state is saved in user preferences and is resumed when you basically say [ session resume ]. What I'm wondering is if I can choose which session to resume based on the uid? If so then I can choose which session to resume. Thanks to all that reply.

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• XML to XHTML - Best Method?

  - by Ian

  Not wishing to be subjective but I have a need to get data from an XML source and convert it to (X)HTML. From my understanding I can do this with PHP (or other server-side scripts), Javascript, or XSLT. My feeling is that it would be more appropriate to use XSLT as it is dealing with an XML source and this is the purpose for which XSLT exists. I also see it having the advantage that it will still work if the user doesn't have Javascript enabled and wont be restricted to a server which runs PHP (or other server-side script). Am I right in my assumptions? Also could the same be same for an RSS feed? Thanks

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• Getting the hang of CodeIgniter - Templating / loading views

  - by kilrizzy

  Attempting to learn CI and going through the docs to get a better understanding. Without getting a separate library, I could make a template by including a list of views like so: $this->load->view('header'); $this->load->view('navigation'); $this->load->view('sidenav_open'); $this->load->view('blocks/userinfo'); $this->load->view('blocks/stats'); $this->load->view('sidenav_close'); $this->load->view('content',$data); $this->load->view('footer'); This makes sense but would I actually have that on each of my controllers (pages)? Not sure if there is a way to include this in the initial controller (welcome) and then in the others somehow reference it? Or perhaps there is something I am missing completely

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• Beginning Programmer Interested in Android - Should I Start with Java?

  - by Hudey

  I'm a beginner in programming. My experience so far is only in Actionscript 2 and 3. So I have a basic understanding of declaring variables, loops, arrays, if/then, do/while... I'm wanting to move to developing for Android phones so I'm wondering what suggestions people have for where to go next. Should I jump right to Android? Start with a 'beginning Java' approach? Or should I go some other route to beef up my knowledge of OOP concepts before launching into Android? I have my Dev environment set up and completed the Hello Android tutorial and I'm just wondering if I am going to be in over my head quickly?

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• MVC Helper Extension issue

  - by BeCool

  Hi, I need to implement a HtmlHelper extension in my MVC project simply just to output some string but ONLY in the DEBUG mode, not in REALEASE. My first attempt would be: [Conditional("DEBUG")] public static string TestStringForDebugOnly(this HtmlHelper helper, string testString) { return testString; } But obviously that would give a compile error: "The Conditional attribute is not valid because its return type is not void." So my understanding is once you set [Condition] attribute, it doesnt allow to return anything? why? What is other way to implement this kind of function? anyone help would be much appreciated. Thanks!

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• PHP MySQL Insert Data

  - by happyCoding25

  Hello, Im trying to insert data into a table in MySQL. I found/modified some code from w3Schools and still couldn't get it working. Heres what I have so far: <?php $rusername=$_POST['username']; $rname=$_POST['name']; $remail=$_POST['emailadr']; $rpassword=$_POST['pass']; $rconfirmpassword=$_POST['cpass']; if ($rpassword==$rconfirmpassword) { $con = mysql_connect("host","user","password"); if (!$con) { die('Could not connect: ' . mysql_error()); } mysql_select_db("mydbname ", $con); } mysql_query("INSERT INTO members (id, username, password) VALUES ('4', $rusername, $rpassword)"); ?> Did I mistype something? To my understanding "members" is the name of the table. If anyone knows whats wrong I appreciate the help. Thanks

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