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• PHP - Drilling down Data and Looping with Loops

  - by stogdilla

  I'm currently having difficulty finding a way of making my loops work. I have a table of data with 15 minute values. I need the data to pull up in a few different increments $filters=Array('Yrs','Qtr','Day','60','30','15'); I think I have a way of finding out what I need to be able to drill down to but the issue I'm having is after the first loop to cycle through all the Outter most values (ex: the user says they want to display by Hours, each hour should be able to have a "+" that will then add a new div to display the half hour data, then each half hour data have a "+" to display the 15 minute data upon request. Now I can just program the number of outputs for each value (6 different outputs) just in-case... but isn't there a way I can make it do the drill down for each one in a loop? so I only have to code one output once and have it just check if there are any more intervals after it and check for those? I'm sure I'm just overlooking some very simple way of doing this but my brain isn't being clever today. Sorry in advance if this is a simple solution. I guess the best way I could think of it as a reply on a form. How you would check to see if it's a reply of a reply, and then if that reply has any replys...etc for output. Can anyone help or at least point me in the right direction? Or am I stuck coding each possible check? Thanks in advance!

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• Greasemonkey failing to GM_setValue()

  - by HonoredMule

  I have a Greasemonkey script that uses a Javascript object to maintain some stored objects. It covers quite a large volume of information, but substantially less than it successfully stored and retrieved prior to encountering my problem. One value refuses to save, and I can not for the life of me determine why. The following problem code: Works for other larger objects being maintained. Is presently handling a smaller total amount of data than previously worked. Is not colliding with any function or other object definitions. Can (optionally) successfully save the problem storage key as "{}" during code startup. this.save = function(table) { var tables = this.tables; if(table) tables = [table]; for(i in tables) { logger.log(this[tables[i]]); logger.log(JSON.stringify(this[tables[i]])); GM_setValue(tables[i] + "_" + this.user, JSON.stringify(this[tables[i]])); logger.log(tables[i] + "_" + this.user + " updated"); logger.log(GM_getValue(tables[i] + "_" + this.user)); } } The problem is consistently reproducible and the logging statments produce the following output in Firebug: Object { 54,10 = Object } // Expansion shows complete contents as expected, but there is one oddity--Firebug highlights the array keys in purple instead of the usual black for anonymous objects. {"54,10":{"x":54,"y":10,"name":"Lucky Pheasant"}} // The correctly parsed string. bookmarks_HonoredMule saved undefined I have tried altering the format of the object keys, to no effect. Further narrowing down the issue is that this particular value is successfully saved as an empty object ("{}") during code initialization, but skipping that also does not help. Reloading the page confirms that saving of the nonempty object truly failed. Any idea what could cause this behavior? I've thoroughly explored the possibility of hitting size constraints, but it doesn't appear that can be the problem--as previously mentioned, I've already reduced storage usage. Other larger objects save still, and the total number of objects, which was not high already, has further been reduced by an amount greater than the quantity of data I'm attempting to store here.

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• using empty on inaccessible object with __isset and __get

  - by David

  <?php class Magic_Methods { protected $meta; public function __construct() { $this->meta = (object) array( 'test' => 1 ); } public function __isset($name) { echo "pass isset {$name} \n"; return isset($this->$name); } public function __get($name) { echo "pass get {$name} \n"; return $this->$name; } } $mm = new Magic_Methods(); $meta = empty($mm->meta->notExisting); var_dump($meta); echo "||\n"; $meta = empty($mm->meta); var_dump($meta); The snippet above does not work as expected for me. Why would the first empty() ommit the __isset? I get this: pass get meta bool(true) || pass isset meta pass get meta bool(false) I would expected identical results or another pass at the __isset, but not a direct call to __get. Or am I missing something here?

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• Doctrine: How to traverse from an entity to another 'linked' entity?

  - by ropstah

  I'm loading 3 different tables using a cross-join in Doctrine_RawSql. This brings me back the following object: User -> User class (doctrine base class) Settings -> DoctrineCollection of Setting User_Settings -> DoctrineCollection of User_Setting The object above is the result of a many-to-many relationship between User and Setting where User_Setting acts as a reference table. User_Setting also contains another field named value. This obviously contains the value of the corresponding Setting. All good so far, however the Settings and User_Settings properties of the returned User object are in no way linked to each other (apart from the setting_id field ofcourse). Is there any direct way to traverse directly from the Settings property to the corresponding User_Settings property? This is the corresponding query: $sets = new Doctrine_RawSql(); $sets->select('{us.*}, {s.*}, {uset.*}') ->from('(User us CROSS JOIN Setting s) LEFT JOIN User_Setting uset ON us.user_id = uset.user_id AND s.setting_id = uset.setting_id') ->addComponent('us', 'User us') ->addComponent('uset', 'us.User_Setting uset') ->addComponent('s', 'us.Setting s') ->where('s.category_id = ? AND us.usr_auto_key = ?',array(1, 1)); $sets = $sets->execute();

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• UITableViewRowAnimationBottom doesn't work for last row

  - by GendoIkari

  I've come across a very similar question here: Inserting row to end of table with UITableViewRowAnimationBottom doesn't animate., though no answers have been given. His code was also a little different than mine. I have an extremely simple example, built from the Navigation application template. NSMutableArray *items; - (void)viewDidLoad { [super viewDidLoad]; items = [[NSMutableArray array] retain]; self.navigationItem.rightBarButtonItem = [[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(addItem)] autorelease]; } - (void)addItem{ [items insertObject:@"new" atIndex:0]; [self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:[NSIndexPath indexPathForRow:0 inSection:0]] withRowAnimation:UITableViewRowAnimationBottom]; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return items.count; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; } cell.textLabel.text = [items objectAtIndex:indexPath.row]; return cell; } - (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath { if (editingStyle == UITableViewCellEditingStyleDelete) { [items removeObjectAtIndex:indexPath.row]; [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationBottom]; } } The problem is, when I either insert or delete the very last row in the table, the animation doesn't work at all; the row just appears or disappears instantly. This only happens with UITableViewRowAnimationBottom, but that's the animation that makes the most sense for creating or deleting table cells in this way. Is this a bug in Apple's framework? Or does it do this on purpose? Would it make sense to add an extra cell to the count, and then setup this cell so that it looks like it's not there at all, just to get around this behavior?

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• Check the code n point the mistake

  - by Vibha

  here is the code: Ext.onReady(function(){ alert("inside onReady"); Ext.QuickTips.init(); var employee = Ext.data.Record.create([ {name:'firstname'}, {name:'lastname'}]); var myReader = new Ext.data.JsonReader({ root:"EmpInfo", },employee); var store = new Ext.data.JsonStore({ id:'ID' ,root:'EmpInfo' ,totalProperty:'totalCount' ,url:'test.php' ,autoLoad:true ,fields:[ {name:'firstname', type:'string'} ,{name:'lastname', type:'string'} ] }); var myPanel = new Ext.grid.GridPanel({ store: store ,columns:[{ dataIndex:'firstname' ,header:'First Name' ,width:139 },{ dataIndex:'lastname' ,header:'Middle Name' ,width:139 } ] }); var myWindow = new Ext.Window({ width:300, height:300, layout:'fit', closable:false, resizable:false, items:[myPanel] }); myWindow.show(); }); And php code is: true, "data" = array( "firstname" = "ABC" , "lastname" = "MNO") ); $_SESSION["err"] = isset($_SESSION["err"]) ? !$_SESSION["err"] : true; header("Content-Type: application/json"); echo json_encode($o); ? I want to print the values ABC and MNO in the grid panel. i'm using extjs 2.3. please help me out. Thanks

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• Any suggestions to improve my PDO connection class?

  - by Scarface

  Hey guys I am pretty new to pdo so I basically just put together a simple connection class using information out of the introductory book I was reading but is this connection efficient? If anyone has any informative suggestions, I would really appreciate it. class PDOConnectionFactory{ public $con = null; // swich database? public $dbType = "mysql"; // connection parameters public $host = "localhost"; public $user = "user"; public $senha = "password"; public $db = "database"; public $persistent = false; // new PDOConnectionFactory( true ) <--- persistent connection // new PDOConnectionFactory() <--- no persistent connection public function PDOConnectionFactory( $persistent=false ){ // it verifies the persistence of the connection if( $persistent != false){ $this->persistent = true; } } public function getConnection(){ try{ $this->con = new PDO($this->dbType.":host=".$this->host.";dbname=".$this->db, $this->user, $this->senha, array( PDO::ATTR_PERSISTENT => $this->persistent ) ); // carried through successfully, it returns connected return $this->con; // in case that an error occurs, it returns the error; }catch ( PDOException $ex ){ echo "We are currently experiencing technical difficulties. We have a bunch of monkies working really hard to fix the problem. Check back soon: ".$ex->getMessage(); } } // close connection public function Close(){ if( $this->con != null ) $this->con = null; } }

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• How do I get require_login()-like functionality using the new PHP Client Library for Facebook?

  - by cc

  Howdy. I've been tasked with making a Facebook game, but I'm new to Facebook development, so I'm just getting started. Apologies in advance if this is a no-brainer to people. I'm having trouble following all the examples I see on sites, and I keep running into missing pages in the Facebook documentation when I am trying to read up. I think it's because there's a new version of the PHP Client Library for Facebook, and everything I'm finding is referring to the old client. For instance, I see this code in a lot of examples: require 'facebook.php'; $facebook = new Facebook( array( 'appId' => '(id)', 'secret' => '(secret)' ) ); $facebook_account = $facebook->require_login(); ...but there's no "require_login()" in the client library provided in the facebook.php file. From what I can tell, it looks like Facebook has very recently rolled out some new system for development, but I don't see any sample code anywhere to deal with it. The new library comes with an "example.php" file, but it appears to be only for adding "Log in with Facebook" functionality to other sites (what I'm assuming is what they mean by "Facebook Connect" sites), not for just running apps in a Canvas page on Facebook itself. Specifically, what I need to do is let users visit an application page within Facebook, have it bring up the dialog box allowing them to authorize the app, have it show up in their "games" page, and then have it pass me the relevant info about the user so I can start creating the game. But I can't seem to find any tutorials or examples that show how to do this using the new library. Seems like this should be pretty straightforward, but I'm running into roadblocks. Or am I missing something about the PHP client library? Should require_login() be working for me, and there's something broken with my implementation, such as having the wrong client library or something? I downloaded from GitHub yesterday, so I'm pretty sure I have the most recent version of the code I have, but perhaps I'm downloading the wrong "facebook.php" file...?

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• Is it possible that two requests at the same time double this code? (prevent double database entry)

  - by loostro

  1) The controller code (Symfony2 framework): $em = $this->getDoctrine()->getEntityManager(); // get latest toplist $last = $em->getRepository('RadioToplistBundle:Toplist')->findOneBy( array('number' => 'DESC') ); // get current year and week of the year $week = date('W'); $year = date('Y'); // if: // [case 1]: $last is null, meaning there are no toplists in the database // [case 2]: $last->getYear() or $last->getWeek() do not match current // year and week number, meaning that there are toplists in the // database, but not for current week // then: // create new toplist entity (for current week of current year) // else: // do nothing (return) if($last && $last->getYear() == $year && $last->getWeek() == $week) return; else { $new = new Toplist(); $new->setYear($year); $new->setWeek($week); $em->persist($new); $em->flush(); } This code is executed with each request to view toplist results (frontend) or list of toplists (backend). Anytime someone wants to access the toplist we first check if we should create a new toplist entity (for new week). 2) The question is: Is it possible that: User A goes to mydomain.com/toplist at 00:00:01 on Monday - the code should generate new entity the server slows down and it takes him 3 seconds to execute the code so new toplist entity is saved to database at 00:00:04 on Monday User B goes to mydomain.com/toplist at 00:00:02 on Monday at 00:00:02 there the toplist is not yet saved in database, thus UserB's request triggers the code to create another toplist entity And so.. after a few seconds we have 2 toplist entities for current week. Is this possible? How should I prevent this?

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• AudioRecord - empty buffer

  - by Arxas

  I' m trying to record some audio using AudioRecord class. Here is my code: int audioSource = AudioSource.MIC; int sampleRateInHz = 44100; int channelConfig = AudioFormat.CHANNEL_IN_MONO; int audioFormat = AudioFormat.ENCODING_PCM_16BIT; int bufferSizeInShorts = 44100; int bufferSizeInBytes = 2*bufferSizeInShorts; short Data[] = new short[bufferSizeInShorts]; Thread recordingThread; AudioRecord audioRecorder = new AudioRecord(audioSource, sampleRateInHz, channelConfig, audioFormat, bufferSizeInBytes); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.activity_main, menu); return true; } public void startRecording(View arg0) { audioRecorder.startRecording(); recordingThread = new Thread(new Runnable() { public void run() { while (Data[bufferSizeInShorts-1] == 0) audioRecorder.read(Data, 0, bufferSizeInShorts); } }); audioRecorder.stop(); } Unfortunately my short array is empty after the recording is over. May I kindly ask you to help me figure out what's wrong?

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• How much is too much memory allocation in NDK?

  - by Maximus

  The NDK download page notes that, "Typical good candidates for the NDK are self-contained, CPU-intensive operations that don't allocate much memory, such as signal processing, physics simulation, and so on." I came from a C background and was excited to try to use the NDK to operate most of my OpenGL ES functions and any native functions related to physics, animation of vertices, etc... I'm finding that I'm relying quite a bit on Native code and wondering if I may be making some mistakes. I've had no trouble with testing at this point, but I'm curious if I may run into problems in the future. For example, I have game struct defined (somewhat like is seen in the San-Angeles example). I'm loading vertex information for objects dynamically (just what is needed for an active game area) so there's quite a bit of memory allocation happening for vertices, normals, texture coordinates, indices and texture graphic data... just to name the essentials. I'm quite careful about freeing what is allocated between game areas. Would I be safer setting some caps on array sizes or should I charge bravely forward as I'm going now?

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• How to marshal an object and its content (also objects)

  - by Waldo Spek

  I have a question for which I suspect the answer is a bit complex. At this moment I am programming a DLL (class library) in C#. This DLL uses a 3rd party library and therefore deals with 3rd party objects of which I do not have the source code. Now I am planning to create another DLL, which is going to be used in a later stadium in my application. This second DLL should use the 3rd party objects (with corresponding object states) created by the first DLL. Luckily the 3rd party objects extend the MarshalByRefObject class. I can marshal the objects using System.Runtime.Remoting.Marshal(...). I then serialize the objects using a BinaryFormatter and store the objects as a byte[] array. All goes well. I can deserialize and unmarshal in a the opposite way and end up with my original 3rd party objects...so it appears... Nevertheless, when calling methods on my 3rd party deserialized objects I get object internal exceptions. Normally these methods return other 3rd party objects, but (obviously - I guess) now these objects are missing because they weren't serialized. Now my global question: how would I go about marshalling/serializing all the objects which my 3rd party objects reference...and cascade down the "reference tree" to obtain a full and complete serialized object? Right now my guess is to preprocess: obtain all the objects and build my own custom object and serialize it. But I'm hoping there is some other way...

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• setMessage for Zend_Validate_EmailAddress doesn't work

  - by iSenne

  Hello everybody. I have a form and I want to set my custom errors in it. I am using Zend, and I have the following code... //Create validators $formMustBeEmail = new Zend_Validate_EmailAddress(); $formMustBeEmail->setMessage(array( Zend_Validate_EmailAddress::INVALID => "1. Invalid type given, value should be a string", Zend_Validate_EmailAddress::INVALID_FORMAT => "2. '%value%' is no valid email address in the basic format local-part@hostname", Zend_Validate_EmailAddress::INVALID_HOSTNAME => "3. '%hostname%' is no valid hostname for email address '%value%'", Zend_Validate_EmailAddress::INVALID_MX_RECORD => "4. '%hostname%' does not appear to have a valid MX record for the email address '%value%'", Zend_Validate_EmailAddress::INVALID_SEGMENT => "5. '%hostname%' is not in a routable network segment. The email address '%value%' should not be resolved from public network.", Zend_Validate_EmailAddress::DOT_ATOM => "6. '%localPart%' can not be matched against dot-atom format", Zend_Validate_EmailAddress::QUOTED_STRING => "7. '%localPart%' can not be matched against quoted-string format", Zend_Validate_EmailAddress::INVALID_LOCAL_PART => "8. '%localPart%' is no valid local part for email address '%value%'", Zend_Validate_EmailAddress::LENGTH_EXCEEDED => "9. '%value%' exceeds the allowed length", Then I make the form... $this->addElement('text', 'email'); $emailElement = $this->getElement('email'); $emailElement ->setLabel('Emailadres') ->setOrder(1) ->setRequired(true) ->addValidator($formMustBeTest) ->addValidator($formMustBeEmail) ->addFilter(new Zend_Filter_StripTags()); But it doesn't work. I still get the normal errors made by Zend. Can anyone see what I am doing wrong? Tnx in advanced...

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• zend-framework doctrine, and mvc pattern: what should connect data between models and forms?

  - by Skirmantas

  I am learning Zend Framework and Doctrine. I am wondering what is the best practice to connect forms to models and vice versa. I don't know where I should put my code. I have seen in Zendcast video tutorials where author creates methods like mapFormToRecord and mapRecordToForm in form class. Well I guess it is very handy when form is sophisticated and uses many records. Is it a good practice? I somehow believe that form-class should not need to know about data-records. And sometimes we might have model which is used in many forms. So It would be handy to have few functions in that model which would help to prepare data for forms. For example to give an array of id=name pairs so that it might be used in Zend_Form_Element_Select. However I would like to have a consistency. So I don't want to put this code nor in model nor in form because on different situations I act different. So only controller is what is left to deal it. However this will result in code duplication if one form will be used more than in one controller. Moreover controller gets bloated if form is not from the simple ones. Or maybe there is a consistent pattern in those data conversions between forms and models? I think that there is. At least in my simple cases. So maybe a separate class could be a solution? Where should I put such class and how should I name it? Another question: Zend_Form has validators and filter. Doctrine has validators and filters too. Which do we use and when? What is your way of dealing the connections between forms and models? (Sorry if it was hard for you to read my text. I don't have enough knowledge of English language to express myself freely)

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• How to understand "if ( obj.length === +obj.length )" Javascript condition statement?

  - by humanityANDpeace

  I have run across a condition statement which I have some difficulties to understand. It looks like (please note the +-sign on the right-hand-side) this: obj.length === +obj.length. Can this condition and its purpose/syntax be explained? Looking at the statement (without knowing it) provokes the impression that it is a dirty hack of some sort, but I am almost certain that underscore.js is rather a well designed library, so there must be a better explanation. Background I found this statement used in some functions of the underscore.js library (underscore.js annotated source). My guesswork is that this condition statement is somehow related to testing for a variable obj to be of Array type? (but I am totally unsure). I have tried to test this using this code. var myArray = [1,2,3]; testResult1 = myArray.length === +myArray.length; console.log( testResult1 ); //prints true var myObject = { foo : "somestring", bar : 123 }; testResult2 = myObject.length === +myObject.length; console.log( testResult2 ); //prints false

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• Seperating and counting CSV entries from database (Access/ASp Classic)

  - by Katherine Perotta

  hey i could really use some help with this one. I have a faq with multiple "tags" and I would like to separate and count them. They are currently in the database as follows: ID-----------------TITLE--------------CONTENT-----------TAGS Sample Records: 1---------------sampletitle 1---------amplecontent--------tag1,tag2,tag3 2---------------sampletitle 2---------moresamplestuff-----tag3,tag4,tag5 How could I go about counting the number of times each tag is used? In the end, would it be easier to just create a separate table called TAGS, with a single tag corresponding to a single ID in FAQ? The only reason I don't prefer doing something like that is because I have so much data already it would take quite a while. However, if there's no alternative or if its easier than doing string parsing like that, im willing to do it. The goal is to display each unique tag and the number of times it is used. Would it be better to do the heavy lifting in the database or ASP? I have gotten as far as getting a list of all tags and displaying them in an array (with each tag separated). So at this point what I need to do is count each value and then remove the duplicates (while preserving the count number somewhere). This is in ASP classic using an Access database. Thanks!

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• In AS3/Flex, how can I get from flat data to hierarchical data?

  - by Dave S

  I have some data that gets pulled out of a database and mapped to an arraycollection. This data has a field called parentid, and I would like to map the data into a new arraycollection with hierarchical information to then feed to an advanced data grid. I think I'm basically trying to take the parent object, add a new property/field/variable of type ArrayCollection called children and then remove the child object from the original list and clone it into the children array? Any help would be greatly appreciated, and I apologize ahead of time for this code: private function PutChildrenWithParents(accountData : ArrayCollection) : ArrayCollection{ var pos_inner:int = 0; var pos_outer:int = 0; while(pos_outer < accountData.length){ if (accountData[pos_outer].ParentId != null){ pos_inner = 0; while(pos_inner < accountData.length){ if (accountData[pos_inner].Id == accountData[pos_outer].ParentId){ accountData.addItemAt( accountData[pos_inner] + {children:new ArrayCollection(accountData[pos_outer])}, pos_inner ); accountData.removeItemAt(pos_outer); accountData.removeItemAt(pos_inner+1); } pos_inner++; } } pos_outer++; } return accountData; }

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• Loading data from file to Vector structure

  - by owca

  I'm trying to parse through fixed-width formatted file extracting x,y values of points from it, and then storing them in int[] array inside a Vector. Text file looks as follows : 0006 0015 0125 0047 0250 0131 That's the code : Vector<int[]> vc = new Vector<int[]>(); try { BufferedReader file = new BufferedReader(new FileReader("myfile.txt")); String s; int[] vec = new int[2]; while ((s = file.readLine()) != null) { vec[0] = Integer.parseInt(s.substring(0, 4).trim()); vec[1] = Integer.parseInt(s.substring(5, 8).trim()); vc.add(vec); } file.close(); } catch (IOException e) { } for(int i=0; i<vc.size(); i++){ for(int j=0; j<2; j++){ System.out.println(vc.elementAt(i)[j]); } } But the output shows only last line. 250 131 250 131 250 131 Should I somehow use Vector.nextElement() here to get all my data ?

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• Is there a way to reload the page after <fb:like> is clicked?

  - by joon

  Hi, I'm wondering about this: I have a simple facebook-connect app that will only show certain content after you login and liked a certain page. It works (huzzah!) but I want to make it more user friendly by making it refresh automatically after you pressed the like button. Here's some code: <?php if ($me) { $pageid = -----------; $uid = $me['id']; $likeID = $facebook->api( array( 'method' => 'fql.query', 'query' => 'SELECT target_id FROM connection WHERE source_id = ' . $uid . ' AND target_id = ' . $pageid ) ); if ( empty($likeID) ) { // Person is LOGGED IN, but has NOT LIKED echo '<script src="MY WEBPAGE"></script><fb:like href="MY WEBPAGE" layout="box_count" show_faces="false" width="450"></fb:like>'; } else { // Person is LOGGED IN, and has LIKED, score! echo 'Download link'; } } else { // Person is NOT LOGGED IN, so we know NOTHING echo '<script src="MY WEBPAGE"></script><fb:like href="MY WEBPAGE" layout="box_count" show_faces="false" width="450"></fb:like>'; } ?> Is there anything I can do to this code (maybe in the fb:like tag?) that makes it reload the page after a like? Thanks.

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• Computation overhead in C# - Using getters/setters vs. modifying arrays directly and casting speeds

  - by Jeffrey Kern

  I was going to write a long-winded post, but I'll boil it down here: I'm trying to emulate the graphical old-school style of the NES via XNA. However, my FPS is SLOW, trying to modify 65K pixels per frame. If I just loop through all 65K pixels and set them to some arbitrary color, I get 64FPS. The code I made to look-up what colors should be placed where, I get 1FPS. I think it is because of my object-orented code. Right now, I have things divided into about six classes, with getters/setters. I'm guessing that I'm at least calling 360K getters per frame, which I think is a lot of overhead. Each class contains either/and-or 1D or 2D arrays containing custom enumerations, int, Color, or Vector2D, bytes. What if I combined all of the classes into just one, and accessed the contents of each array directly? The code would look a mess, and ditch the concepts of object-oriented coding, but the speed might be much faster. I'm also not concerned about access violations, as any attempts to get/set the data in the arrays will done in blocks. E.g., all writing to arrays will take place before any data is accessed from them. As for casting, I stated that I'm using custom enumerations, int, Color, and Vector2D, bytes. Which data types are fastest to use and access in the .net Framework, XNA, XBox, C#? I think that constant casting might be a cause of slowdown here. Also, instead of using math to figure out which indexes data should be placed in, I've used precomputed lookup tables so I don't have to use constant multiplication, addition, subtraction, division per frame. :)

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• Best (Java) book for understanding 'under the bonnet' for programming?

  - by Ben

  What would you say is the best book to buy to understand exactly how programming works under the hood in order to increase performance? I've coded in assembly at university, I studied computer architecture and I obviously did high level programming, but what I really dont understand is things like: -what is happening when I perform a cast -whats the difference in performance if I declare something global as opposed to local? -How does the memory layout for an ArrayList compare with a Vector or LinkedList? -Whats the overhead with pointers? -Are locks more efficient than using synchronized? -Would creating my own array using int[] be faster than using ArrayList -Advantages/disadvantages of declaring a variable volatile I have got a copy of Java Performance Tuning but it doesnt go down very low and it contains rather obvious things like suggesting a hashmap instead of using an ArrayList as you can map the keys to memory addresses etc. I want something a bit more Computer Sciencey, linking the programming language to what happens with the assembler/hardware. The reason im asking is that I have an interview coming up for a job in High Frequency Trading and everything has to be as efficient as possible, yet I cant remember every single possible efficiency saving so i'd just like to learn the fundamentals. Thanks in advance

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• Android game logic problem

  - by semajhan

  I'm currently creating a game and have a problem which I think I know why it is occurring but not entirely sure and even if I knew, don't know how to solve. I have a 2D array 10 x 10 and have a "player" class that takes up a tile. Now, I have created 2 instances of the player and move them around via swiping. Around the edges I have put "walls" that the player cannot walk through and everything works fine, until I remove a wall. Once I remove a wall and move the character/player to the edge of the screen, the player cannot go any further. The problem occurs here, where the second instance of the player is not at the edge of the screen but say 2 tiles from the first instance of "player" who is at the edge. If I try moving them further into the direction of the edge, I understand that the first instance of player wouldn't move or do anything but the second instance of player should still move, but it won't. This is the code that executed when the user swipes: if (player.getArrayX() - 1 != player2.getArrayX()) { player.moveLeft(); } else if (player.getArrayX() - 1 == player2.getArrayX() && player.getArrayY() != player2.getArrayY()) { player.moveLeft(); } if (player2.getArrayX() - 1 != player.getArrayX()) { player2.moveLeft(); } else if (player2.getArrayX() - 1 == player.getArrayX() && player2.getArrayY() != player.getArrayY()) { player2.moveLeft(); } In the player class I have: public void moveLeft() { if (alive) { switch (levelMaster.getLevel1(getArrayX() - 1, getArrayY())) { case 0: break; case 1: subX(); // basically moves player left setArrayX(getArrayX() - 1); // shifts x coord of player 1 within tilemap Log.d("semajhan", "x: " + getArrayX()); break; case 9: subX(); setArrayX(getArrayX() - 1); setAlive(false); break; } } } Any help on the matter or further insight would be greatly appreciated, thanks.

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• How to insert and call by row and column into sqlite3 python, great tutorial problem.

  - by user291071

  Lets say i have a simple array of x rows and y columns with corresponding values, What is the best method to do 3 things? How to insert, update a value at a specific row column? How to select a value for each row and column, import sqlite3 con = sqlite3.connect('simple.db') c = con.cursor() c.execute('''create table simple (links text)''') con.commit() dic = {'x1':{'y1':1.0,'y2':0.0},'x2':{'y1':0.0,'y2':2.0,'y3':1.5},'x3':{'y2':2.0,'y3':1.5}} ucols = {} ## my current thoughts are collect all row values and all column values from dic and populate table row and columns accordingly how to call by row and column i havn't figured out yet ##populate rows in first column for row in dic: print row c.execute("""insert into simple ('links') values ('%s')"""%row) con.commit() ##unique columns for row in dic: print row for col in dic[row]: print col ucols[col]=dic[row][col] ##populate columns for col in ucols: print col c.execute("alter table simple add column '%s' 'float'" % col) con.commit() #functions needed ##insert values into sql by row x and column y?how to do this e.g. x1 and y2 should put in 0.0 ##I tried as follows didn't work for row in dic: for col in dic[row]: val =dic[row][col] c.execute("""update simple SET '%s' = '%f' WHERE 'links'='%s'"""%(col,val,row)) con.commit() ##update value at a specific row x and column y? ## select a value at a specific row x and column y?

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• Avoid using InetAddress - Getting a raw IP address in network byte order

  - by Mylo

  Hey, I am trying to use the MaxMind GeoLite Country database on the Google App Engine. However, I am having difficulty getting the Java API to work as it relies on the InetAddress class which is not available to use on the App Engine. However, I am not sure if there is a simple workaround as it appears it only uses the InetAddress class to determine the IP of a given hostname. In my case, the hostname is always an IP anyway. What I need is a way to convert an IP address represented as a String into a byte array of network byte order (which the addr.getAddress() method of the InetAddress class provides). This is the code the current API uses, I need to find a way of removing all references to InetAddress whilst ensuring it still works! Thanks for your time. /** * Returns the country the IP address is in. * * @param ipAddress String version of an IP address, i.e. "127.0.0.1" * @return the country the IP address is from. */ public Country getCountry(String ipAddress) { InetAddress addr; try { addr = InetAddress.getByName(ipAddress); } catch (UnknownHostException e) { return UNKNOWN_COUNTRY; } return getCountry(bytesToLong(addr.getAddress())); }

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• MySQL: Combining multiple where conditions

  - by Karl

  I'm working on a menu system that takes a url and then queries the db to build the menu. My menu table is: +---------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------+--------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | node_id | int(11) | YES | | NULL | | | parent | int(11) | YES | | NULL | | | weight | int(11) | YES | | NULL | | | title | varchar(250) | YES | | NULL | | | alias | varchar(250) | YES | | NULL | | | exclude | int(11) | YES | | NULL | | +---------+--------------+------+-----+---------+----------------+ The relevant columns for my question are alias, parent and node_id. So for a url like: http://example.com/folder1/folder2/filename Alias would potentially = "filename", "folder1", "folder2" Parent = the node_id of the parent folder. What I know is how to split the url up into an array and check the alias for a match to each part. What I don't know is how to have it then filter by parent whose alias matches "folder2" and whose parent alias matches "folder1". I'm imagining a query like so: select * from menu where alias='filename' and where parent = node_id where alias='folder2' and parent = node_id where alias='folder1' Except I know that the above is wrong. I'm hoping this can be done in a single query. Thanks for any help in advance!

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