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  • SQL wont work? It doesn't come up with errors either

    - by Stefan
    Hey there, I have php function which checks to see if variables are set and then adds them onto my sql query. However I am don't seem to be getting any results back!? $where_array = array(); if (array_key_exists("location", $_GET)) { $location = addslashes($_GET['location']); $where_array[] = "`mainID` = '".$location."'"; } if (array_key_exists("gender", $_GET)) { $gender = addslashes($_GET["gender"]); $where_array[] = "`gender` = '".$gender."'"; } if (array_key_exists("hair", $_GET)) { $hair = addslashes($_GET["hair"]); $where_array[] = "`hair` = '".$hair."'"; } if (array_key_exists("area", $_GET)) { $area = addslashes($_GET["area"]); $where_array[] = "`locationID` = '".$area."'"; } $where_expr = ''; if ($where_array) { $where_expr = "WHERE " . implode(" AND ", $where_array); } $sql = "SELECT `postID` FROM `posts` ". $where_expr; $dbi = new db(); $result = $dbi->query($sql); $r = mysql_fetch_row($result); I'm trying to call the data after in a list like so: $dbi = new db(); $offset = ($currentpage - 1) * $rowsperpage; // get the info from the db $sql .= " ORDER BY `time` DESC LIMIT $offset, $rowsperpage"; $result = $dbi->query($sql); // while there are rows to be fetched... while ($row = mysql_fetch_object($result)){ // echo data echo $row['text']; } // end while Anyone got any ideas why I am not retrieving any data? -Stefan

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  • magento category tree menu query being called on every page

    - by user1173309
    I have this query being called on every page in Magento CE 1.6.2, to find out where is it being called from, I have disabled all modules, removed the customizations done but it's still being called, this query is slowing up the page loading time and am at my wit's end trying to find out how can I stop it from being executed. The query is given below, for simplcitiy, I have removed lot of category id' to keep the sql short, it would be great if I could get solutions or hints to stop this query being called. SELECT e.*, IF(at_is_active.value_id 0, at_is_active.value, at_is_active_default.value) AS is_active, IF(at_include_in_menu.value_id 0, at_include_in_menu.value, at_include_in_menu_default.value) AS include_in_menu, core_url_rewrite.request_path FROM catalog_category_entity AS e INNER JOIN catalog_category_entity_int AS at_is_active_default ON (at_is_active_default.entity_id = e.entity_id) AND (at_is_active_default.attribute_id = '119') AND at_is_active_default.store_id = 0 LEFT JOIN catalog_category_entity_int AS at_is_active ON (at_is_active.entity_id = e.entity_id) AND (at_is_active.attribute_id = '119') AND (at_is_active.store_id = 1) INNER JOIN catalog_category_entity_int AS at_include_in_menu_default ON (at_include_in_menu_default.entity_id = e.entity_id) AND (at_include_in_menu_default.attribute_id = '934') AND at_include_in_menu_default.store_id = 0 LEFT JOIN catalog_category_entity_int AS at_include_in_menu ON (at_include_in_menu.entity_id = e.entity_id) AND (at_include_in_menu.attribute_id = '934') AND (at_include_in_menu.store_id = 1) LEFT JOIN core_url_rewrite ON (core_url_rewrite.category_id=e.entity_id) AND (core_url_rewrite.is_system=1 AND core_url_rewrite.product_id IS NULL AND core_url_rewrite.store_id='1' AND id_path LIKE 'category/%') WHERE (e.entity_type_id = '9') AND (e.entity_id IN('105', '125', '284', '285', '286', '288', '289', '185', '463', '464', '465', '625')) AND (e.entity_id NOT IN('140', '145', '530', '531', '775')) AND (IF(at_is_active.value_id 0, at_is_active.value, at_is_active_default.value) = '1') AND (IF(at_include_in_menu.value_id 0, at_include_in_menu.value, at_include_in_menu_default.value) = '1') Cheers Arjun

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  • jQuery and AJAX?

    - by Moshe
    I'm making a simple form which has 5 input elements for parts of an address. I use jQuery to build and send an AJAX request to a PHP file on my server. For some reason my jQuery is not properly able to read the values from my input elements. What could be wrong? Here is my jQuery: $('#submitButton').click(function(){ $('#BBRequestBox').html('<img src="images/loading.gif" />'); alert('Info: ' + $('#name').val() + ' ' + $('#street').val() + ' ' + $('#city').val() + ' ' + $('#state').val() + ' ' + $('#zip').val() + ' '); $.ajax({ type: "POST", url: "./bbrequest.php", data: {name: $('#name').val(), street: $('#street').val(), city: $('#city').val(), state: $('#state').val(), zip: $('#zip').val() }, success: function(msg){ $('#BBRequestBox').html('<p>' + msg + '</p>'); }, error: function(XMLHttpRequest, textStatus, errorThrown){ $('#BBRequestBox').html('<p> There\'s been an error: ' + errorThrown + '</p>'); } }); return false; }); Here is my HTML: <form action="#"> <label>Name:</label><input type="text" id="name" class="textbox"/> <label>Street:</label><input type="text" id="street" class="textbox" /> <label>City:</label><input type="text" id="city"class="textbox" /> <label>State:</label><input type="text" id="state" class="textbox"/> <label>Zip:</label><input type="text" id="zip" class="textbox" /> <input type="submit" value="Send Me a Bitachon Builder!" id="submitButton" /> </form>

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  • Initialising vals which might throw an exception

    - by Paul Butcher
    I need to initialise a set of vals, where the code to initialise them might throw an exception. I'd love to write: try { val x = ... generate x value ... val y = ... generate y value ... } catch { ... exception handling ... } ... use x and y ... But this (obviously) doesn't work because x and y aren't in scope outside of the try. It's easy to solve the problem by using mutable variables: var x: Whatever = _ var y: Whatever = _ try { x = ... generate x value ... y = ... generate y value ... } catch { ... exception handling ... } ... use x and y ... But that's not exactly very nice. It's also easy to solve the problem by duplicating the exception handling: val x = try { ... generate x value ... } catch { ... exception handling ... } val y = try { ... generate y value ... } catch { ... exception handling ... } ... use x and y ... But that involves duplicating the exception handling. There must be a "nice" way, but it's eluding me.

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  • Load images into separate movie clips from a XML, Flash, Actionscript 3.0

    - by James Dunay
    I have an xml image bank, pretty standard, and I have a loader, along with movie clips that I want the images loaded into, the problem that I am running into is I want the images to load into separate movie clips, so I’m using a case statement to specify where they go. However, I can only get them to load into a single movie clip, I assume they are loading ontop of each other and I don’t know how to get them to separate out. I’ll post my code. It doesn’t make any sense to me but if you have any suggestions that would be real great. I can make separate loaders and then just do 1 image per loader, but that just doesn’t sound right to me. var counterNumber:Number = 0; function callThumbs():void{ for (var i:Number = 0; i <3; i++){ thumbLoaded(); counterNumber++; } } function thumbLoaded(){ var photoLoader = new Loader(); switch (counterNumber){ case 1: photoLoader.load(new URLRequest(MovieClip(this.parent).xml.photos.imageOne.image.@url[0])); whole.boxOne.pictureLoader.addChild(photoLoader); trace("1Done"); break; case 2: photoLoader.load(new URLRequest(MovieClip(this.parent).xml.photos.imageTwo.image.@url[0])); whole.boxTwo.pictureLoader.addChild(photoLoader); trace("2Done"); break; } }

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  • C++ converting back and forth from derived and base classes

    - by user127817
    I was wondering if there is a way in C++ to accomplish the following: I have a base class called ResultBase and two class that are Derived from it, Variable and Expression. I have a few methods that do work on vector<ResultBase> . I want to be able to pass in vectors of Variable and Expression into these methods. I can achieve this by creating a vector<ResultBase> and using static_cast to fill it with the members from my vector of Variable/Expression. However, once the vector has run through the methods, I want to be able to get it back as the vector of Result/Expression. I'll know for sure which one I want back. static_cast won't work here as there isn't a method to reconstruct a Variable/Expression from a ResultBase, and more importantly I wouldn't have the original properties of the Variables/Expressions The methods modify some of the properties of the ResultBase and I need those changes to be reflected in the original vectors. (i.e. ResultBase has a property called IsLive, and one of the methods will modify this property. I want this IsLive value to be reflected in the derived class used to create the ResultBase Whats the easiest way to accomplish this?

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  • Regex: match a non nested code block

    - by Sylvanas Garde
    I am currently writing a small texteditor. With this texteditor users are able to create small scripts for a very simple scripting engine. For a better overview I want to highlight codeblocks with the same command like GoTo(x,y) or Draw(x,y). To achieve this I want to use Regular Expresions (I am already using it to highlight other things like variables) Here is my Expression (I know it's very ugly): /(?<!GoTo|Draw|Example)(^(?:GoTo|Draw|Example)\(.+\)*?$)+(?!GoTo|Draw|Example)/gm It matches the following: lala GoTo(5656) -> MATCH 1 sdsd GoTo(sdsd) --comment -> MATCH 2 GoTo(23329); -> MATCH 3 Test() GoTo(12) -> MATCH 4 LALA Draw(23) -> MATCH 5 Draw(24) -> MATCH 6 Draw(25) -> MATCH 7 But what I want to achieve is, that the complete "blocks" of the same command are matched. In this case Match 2 & 4 and Match 5 & 6 & 7 should be one match. Tested with http://regex101.com/, the programming lanuage is vb.net. Any advise would be very useful, Thanks in advance!

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  • Finding cause of memory leaks in large PHP stacks

    - by Mike B
    I have CLI script that runs over several thousand iterations between runs and it appears to have a memory leak. I'm using a tweaked version of Zend Framework with Smarty for view templating and each iteration uses several MB worth of code. The first run immediately uses nearly 8MB of memory (which is fine) but every following run adds about 80kb. My main loop looks like this (very simplified) $users = UsersModel::getUsers(); foreach($users as $user) { $obj = new doSomethingAwesome(); $obj->run($user); $obj = null; unset($obj); } The point is that everything in scope should be unset and the memory freed. My understanding is that PHP runs through its garbage collection process at it's own desire but it does so at the end of functions/methods/scripts. So something must be leaking memory inside doSomethingAwesome() but as I said it is a huge stack of code. Ideally, I would love to find some sort of tool that displayed all my variables no matter the scope at some point during execution. Some sort of symbol-table viewer for php. Does anything like that or any other tools that could help nail down memory leaks in php exist?

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  • Entity Framework + MySQL - Why is the performance so terrible?

    - by Cyril Gupta
    When I decided to use an OR/M (Entity Framework for MySQL this time) for my new project I was hoping it would save me time, but I seem to have failed it (for the second time now). Take this simple SQL Query SELECT * FROM POST ORDER BY addedOn DESC LIMIT 0, 50 It executes and gives me results in less than a second as it should (the table has about 60,000 rows). Here's the equivalent LINQ To Entities query that I wrote for this var q = (from p in db.post orderby p.addedOn descending select p).Take(50); var q1 = q.ToList(); //This is where the query is fetched and timed out But this query never even executes it times out ALWAYS (without orderby it takes 5 seconds to run)! My timeout is set to 12 seconds so you can imagine it is taking much more than that. Why is this happening? Is there a way I can see what is the actual SQL Query that Entity Framework is sending to the db? Should I give up on EF+MySQL and move to standard SQL before I lose all eternity trying to make it work? I've recalibrated my indexes, tried eager loading (which actually makes it fail even without the orderby clause) Please help, I am about to give up OR/M for MySQL as a lost cause.

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  • C++ Constructor initialization list strangeness

    - by Andy
    I have always been a good boy when writing my classes, prefixing all member variables with m_: class Test { int m_int1; int m_int2; public: Test(int int1, int int2) : m_int1(int int1), m_int2(int int2) {} }; void main() { Test t(10, 20); // Just an example } However, recently I forgot to do that and ended up writing: class Test { int int1; int int2; public: // Very questionable, but of course I meant to assign ::int1 to this->int1! Test(int int1, int int2) : int1(int1), int2(int2) {} }; Believe it or not, the code compiled with no errors/warnings and the assignments took place correctly! It was only when doing the final check before checking in my code when I realised what I had done. My question is: why did my code compile? Is something like that allowed in the C++ standard, or is it simply a case of the compiler being clever? In case you were wondering, I was using Visual Studio 2008 Thank you.

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  • Applying correct bindings to WPF datatemplate to maximize reusability

    - by johncatfish
    Hi. I have a WPF application. I want to apply that datatemplate to a Listbox filled with records from Table02. Then, for each listboxitem I need to bind the combobox to the same database table (Table01), but for each listboxitem the selected item will vary. It will be a foreign key to Table01. <DataTemplate x:Key="Table01DataTemplate"> <Grid> <ComboBox ItemsSource="{Binding Model.IQueryable_Table01, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}}" SelectedValue="{Binding Table01_ForeignKey}" DisplayMemberPath="name" SelectedValuePath="id" /> <!-- Other stuff --> </Grid> </DataTemplate> <ListBox x:Name="lbTest" ItemTemplate="{StaticResource Table01DataTemplate}" /> <!-- In .cs file lbTest.DataContext = this; --> Notes: Model.IQueryable_Table01 is a property which encapsulates a Linq-to-sql call returning a IQueryable. lbTest will be filled by setting ItemsSource with a Linq-to-sql call. Is this a good way to do the bindings in a data template for a maximum reusability? I also thought of replacing AncestorType={x:Type Window} with lbTest.DataContext = this; AncestorType={x:Type Application} and lbTest.DataContext = App.Current; But it didn't work (Exception on loading) and I don't know if there's any caveats or down-sides to this approach. Is this good? Any suggestions or improvements? Thanks.

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  • jquery append 'x' number images elements applying 'x' to src and class

    - by Yusaf
    I have a directory with 590 pictures and my issue is being able to pull images using jquery alone from that directory and appending them which i have found out can not be done alone using jquery/javascript. alternatively i have renamed the pictures 1.jpg,2.jpg ... 590.jpg . how using jquery can i append 590 images to a div leaving me with the number of the appended element applied to the src being 'lq'+numberofappended+'.jpg' and class being 'image-'+numberofappended as a result leaving me with the below <div class="imagecontainer"> <img src="lq/1.jpg" class="image-1"/> <img src="lq/2.jpg" class="image-2"/> <img src="lq/3.jpg" class="image-3"/> ... <img src="lq/590.jpg" class="image-590"/> </div> if what I have will be too extensive can i append 50 images at a time and apply a jquery pagination loading another 50 each time i reach the end of the page. I personally know how to use append in jquery but I don't know how to individually append an image and depending on which append number it is applying it to the src and class.

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  • iOS - Passing variable to view controller

    - by gj15987
    I have a view with a view controller and when I show this view on screen, I want to be able to pass variables to it from the calling class, so that I can set the values of labels etc. First, I just tried creating a property for one of the labels, and calling that from the calling class. For example: SetTeamsViewController *vc = [[SetTeamsViewController alloc] init]; vc.myLabel.text = self.teamCount; [self presentModalViewController:vc animated:YES]; [vc release]; However, this didn't work. So I tried creating a convenience initializer. SetTeamsViewController *vc = [[SetTeamsViewController alloc] initWithTeamCount:self.teamCount]; And then in the SetTeamsViewController I had - (id)initWithTeamCount:(int)teamCount { self = [super initWithNibName:nil bundle:nil]; if (self) { // Custom initialization self.teamCountLabel.text = [NSString stringWithFormat:@"%d",teamCount]; } return self; } However, this didn't work either. It's just loading whatever value I've given the label in the nib file. I've littered the code with NSLog()s and it is passing the correct variable values around, it's just not setting the label. Any help would be greatly appreciated. EDIT: I've just tried setting an instance variable in my designated initializer, and then setting the label in viewDidLoad and that works! Is this the best way to do this? Also, when dismissing this modal view controller, I update the text of a button in the view of the calling ViewController too. However, if I press this button again (to show the modal view again) whilst the other view is animating on screen, the button temporarily has it's original value again (from the nib). Does anyone know why this is?

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  • How to store and remove dynamically and automatic variable of generic data type in custum list data

    - by Vineel Kumar Reddy
    Hi I have created a List data structure implementation for generic data type with each node declared as following. struct Node { void *data; .... .... } So each node in my list will have pointer to the actual data(generic could be anything) item that should be stored in the list. I have following signature for adding a node to the list AddNode(struct List *list, void* eledata); the problem is when i want to remove a node i want to free even the data block pointed by *data pointer inside the node structure that is going to be freed. at first freeing of datablock seems to be straight forward free(data) // forget about the syntax..... But if data is pointing to a block created by malloc then the above call is fine....and we can free that block using free function int *x = (int*) malloc(sizeof(int)); *x = 10; AddNode(list,(void*)x); // x can be freed as it was created using malloc what if a node is created as following int x = 10; AddNode(list,(void*)&x); // x cannot be freed as it was not created using malloc Here we cannot call free on variable x!!!! How do i know or implement the functionality for both dynamically allocated variables and static ones....that are passed to my list.... Thanks in advance...

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  • Most readable way to write simple conditional check

    - by JRL
    What would be the most readable/best way to write a multiple conditional check such as shown below? Two possibilities that I could think of (this is Java but the language really doesn't matter here): Option 1: boolean c1 = passwordField.getPassword().length > 0; boolean c2 = !stationIDTextField.getText().trim().isEmpty(); boolean c3 = !userNameTextField.getText().trim().isEmpty(); if (c1 && c2 && c3) { okButton.setEnabled(true); } Option 2: if (passwordField.getPassword().length > 0 && !stationIDTextField.getText().trim().isEmpty() && !userNameTextField.getText().trim().isEmpty() { okButton.setEnabled(true); } What I don't like about option 2 is that the line wraps and then indentation becomes a pain. What I don't like about option 1 is that it creates variables for nothing and requires looking at two places. So what do you think? Any other options?

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  • How can I clear viewstate of a dropdownlist inside a usercontrol? Should I?

    - by tbilly
    I have a web user control with a dropdownlist inside of it. When the usercontrol's databind event is called, it automatically fires the dropdownlists databind event. In the dropdownlist's ondatabound event handler an 'other' option is appended to the end of the dropdownlist. The usercontrol is loaded multiple times, depending on selection of other controls on the page. When the page loads initially, there are no items in the usercontrol except the 'other' option. Then when I call the user control's databind event the control reloads, with 4 items plus the 'other' option. The text for the first item in the list is the 'other' option's text, not what it should be. I've stepped through the databound event of the dropdownlist and have found that all items are loading correctly. It appears that the dropdownlist's viewstate is the culprit, that the dropdownlist's original item[1] text is overwriting the new text. I've tried disabling viewstate on the dropdownlist, but then it wouldn't load at all. Should I try to clear the dropdownlist's viewstate? How do I do that? Any suggestions would be greatly appreciated.

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  • How to create view model without sorting collections in memory.

    - by Chevex
    I have a view model (below). public class TopicsViewModel { public Topic Topic { get; set; } public Reply LastReply { get; set; } } I want to populate an IQueryable<TopicsViewModel> with values from my IQueryable<Topic> collection and IQueryable<Reply> collection. I do not want to use the attached entity collection (i.e. Topic.Replies) because I only want the last reply for that topic and doing Topic.Replies.Last() loads the entire entity collection in memory and then grabs the last one in the list. I am trying to stay in IQueryable so that the query is executed in the database. I also don't want to foreach through topics and query replyRepository.Replies because looping through IQueryable<Topic> will start the lazy loading. I'd prefer to build one expression and have all the leg work done in the lower layers. I have the following: IQueryable<TopicsViewModel> topicsViewModel = from x in topicRepository.Topics from y in replyRepository.Replies where y.TopicID == x.TopicID orderby y.PostedDate ascending select new TopicsViewModel { Topic = x, LastReply = y }; But this isn't working. Any ideas how I can populate an IQueryable or IEnumerable of TopicsViewModel so that it queries the database and grabs topics and that topic's last reply? I am trying really hard to avoid grabbing all replies related to that topic. I only want to grab the last reply. Thank you for any insight you have to offer.

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  • jquery touch punch - draggable on ipad

    - by dshuta
    i am starting to work with the jquery touch punch extensions in order to allow draggability on ipad, but i am getting tripped up right away. probably something terribly dumb on my part. the draggable example from the developer works fine on my ipad: http://furf.com/exp/touch-punch/draggable.html but not for me: http://danshuta.com/touchpunch/ this works fine in my desktop browser, but on the ipad it just focuses on the block and scrolls the entire page as i drag, as if it were just an image or other normal embedded object. as this is what happens normally with jquery/ui on ipad, this makes me think it is not loading or otherwise ignoring the "punch" code from my site (though if i host the jquery files on my site via the same path, those load and function fine in desktop browser). here's the entire code, very basic: <!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8" /> <title>Touchpunchtest</title> <script src="http://code.jquery.com/jquery.min.js"></script> <script src="http://code.jquery.com/ui/1.8.17/jquery-ui.min.js"></script> <script src="js/jquery.ui.touch-punch.js"></script> </head> <body> <div id="draggybox" onclick="void(0)" style="width: 150px; height: 150px; background: green;"></div> <script>$('#draggybox').draggable();</script> </body> </html> what am i missing?!

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  • Function behaviour on shell(ksh) script

    - by footy
    Here are 2 different versions of a program: this Program: #!/usr/bin/ksh printmsg() { i=1 print "hello function :)"; } i=0; echo I printed `printmsg`; printmsg echo $i Output: # ksh e I printed hello function :) hello function :) 1 and Program: #!/usr/bin/ksh printmsg() { i=1 print "hello function :)"; } i=0; echo I printed `printmsg`; echo $i Output: # ksh e I printed hello function :) 0 The only difference between the above 2 programs is that printmsg is 2times in the above program while printmsg is called once in the below program. My Doubt arises here: To quote Be warned: Functions act almost just like external scripts... except that by default, all variables are SHARED between the same ksh process! If you change a variable name inside a function.... that variable's value will still be changed after you have left the function!! But we can clearly see in the 2nd program's output that the value of i remains unchanged. But we are sure that the function is called as the print statement gets the the output of the function and prints it. So why is the output different in both?

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  • Javascript problem with iframe that's hidden before loaded

    - by Aistina
    I have a page that contains an iframe that gets loaded using Javascript: index.html <iframe id="myFrame" width="800" height="600" style="display: none;"></iframe> <div id="loader"><!-- some loading indicator --></div> <script type="text/javascript"> function someFunction() { var myFrame = document.getElementById('myFrame'); var loader = document.getElementById('loader'); loader.style.display = 'block'; myFrame.src = 'myFrame.html'; myFrame.onload = function() { myFrame.style.display = 'block'; loader.style.display = 'none'; }; } </script> The page that gets loaded in the iframe contains some Javascript logic which calculates the sizes of certain elements for the purposes of adding a JS driven scrollbar (jScrollPane + jQuery Dimensions). myFrame.html <div id="scrollingElement" style="overflow: auto;"> <div id="several"></div> <div id="child"></div> <div id="elements"></div> </div> <script type="text/javascript"> $(document).load(function() { $('#scrollingElement').jScrollPane(); }); </script> This works in Chrome (and probably other Webkit browsers), but fails in Firefox and IE because at the time jScrollPane gets called, all the elements are still invisble and jQuery Dimensions is unable to determine any element's dimensions. Is there a way to make sure my iframe is visible before $(document).ready(...) gets called? Other than using setTimeout to delay jScrollPane, which is something I definitely want to avoid.

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  • Extremely CPU Intensive Alarm Clock

    - by SoulBeaver
    For some reason my program, a console alarm clock I made for laughs and practice, is extremely CPU intensive. It consumes about 2mB RAM, which is already quite a bit for such a small program, but it devastates my CPU with over 50% resources at times. Most of the time my program is doing nothing except counting down the seconds, so I guess this part of my program is the one that's causing so much strain on my CPU, though I don't know why. If it is so, could you please recommend a way of making it less, or perhaps a library to use instead if the problem can't be easily solved? /* The wait function waits exactly one second before returning to the * * called function. */ void wait( const int &seconds ) { clock_t endwait; // Type needed to compare with clock() endwait = clock() + ( seconds * CLOCKS_PER_SEC ); while( clock() < endwait ) {} // Nothing need be done here. } In case anybody browses CPlusPlus.com, this is a genuine copy/paste of the clock() function they have written as an example for clock(). Much why the comment //Nothing need be done here is so lackluster. I'm not entirely sure what exactly clock() does yet. The rest of the program calls two other functions that only activate every sixty seconds, otherwise returning to the caller and counting down another second, so I don't think that's too CPU intensive- though I wouldn't know, this is my first attempt at optimizing code. The first function is a console clear using system("cls") which, I know, is really, really slow and not a good idea. I will be changing that post-haste, but, since it only activates every 60 seconds and there is a noticeable lag-spike, I know this isn't the problem most of the time. The second function re-writes the content of the screen with the updated remaining time also only every sixty seconds. I will edit in the function that calls wait, clearScreen and display if it's clear that this function is not the problem. I already tried to reference most variables so they are not copied, as well as avoid endl as I heard that it's a little slow compared to \n.

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  • How to handle 'this' pointer in constructor?

    - by Kyle
    I have objects which create other child objects within their constructors, passing 'this' so the child can save a pointer back to its parent. I use boost::shared_ptr extensively in my programming as a safer alternative to std::auto_ptr or raw pointers. So the child would have code such as shared_ptr<Parent>, and boost provides the shared_from_this() method which the parent can give to the child. My problem is that shared_from_this() cannot be used in a constructor, which isn't really a crime because 'this' should not be used in a constructor anyways unless you know what you're doing and don't mind the limitations. Google's C++ Style Guide states that constructors should merely set member variables to their initial values. Any complex initialization should go in an explicit Init() method. This solves the 'this-in-constructor' problem as well as a few others as well. What bothers me is that people using your code now must remember to call Init() every time they construct one of your objects. The only way I can think of to enforce this is by having an assertion that Init() has already been called at the top of every member function, but this is tedious to write and cumbersome to execute. Are there any idioms out there that solve this problem at any step along the way?

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  • Can C++ do something like an ML case expression?

    - by Nathan Andrew Mullenax
    So, I've run into this sort of thing a few times in C++ where I'd really like to write something like case (a,b,c,d) of (true, true, _, _ ) => expr | (false, true, _, false) => expr | ... But in C++, I invariably end up with something like this: bool c11 = color1.count(e.first)>0; bool c21 = color2.count(e.first)>0; bool c12 = color1.count(e.second)>0; bool c22 = color2.count(e.second)>0; // no vertex in this edge is colored // requeue if( !(c11||c21||c12||c22) ) { edges.push(e); } // endpoints already same color // failure condition else if( (c11&&c12)||(c21&&c22) ) { results.push_back("NOT BICOLORABLE."); return true; } // nothing to do: nodes are already // colored and different from one another else if( (c11&&c22)||(c21&&c12) ) { } // first is c1, second is not set else if( c11 && !(c12||c22) ) { color2.insert( e.second ); } // first is c2, second is not set else if( c21 && !(c12||c22) ) { color1.insert( e.second ); } // first is not set, second is c1 else if( !(c11||c21) && c12 ) { color2.insert( e.first ); } // first is not set, second is c2 else if( !(c11||c21) && c22 ) { color1.insert( e.first ); } else { std::cout << "Something went wrong.\n"; } I'm wondering if there's any way to clean all of those if's and else's up, as it seems especially error prone. It would be even better if it were possible to get the compiler complain like SML does when a case expression (or statement in C++) isn't exhaustive. I realize this question is a bit vague. Maybe, in sum, how would one represent an exhaustive truth table with an arbitrary number of variables in C++ succinctly? Thanks in advance.

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  • Any problems with this C++ const reference accessor interface idiom?

    - by mskfisher
    I was converting a struct to a class so I could enforce a setter interface for my variables. I did not want to change all of the instances where the variable was read, though. So I converted this: struct foo_t { int x; float y; }; to this: class foo_t { int _x; float _y; public: foot_t() : x(_x), y(_y) { set(0, 0.0); } const int &x; const float &y; set(int x, float y) { _x = x; _y = y; } }; I'm interested in this because it seems to model C#'s idea of public read-only properties. Compiles fine, and I haven't seen any problems yet. Besides the boilerplate of associating the const references in the constructor, what are the downsides to this method? Any strange aliasing issues? Why haven't I seen this idiom before?

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  • How to check whether user is login in web application?

    - by Morgan Cheng
    I want to learn the whole details of web application authentication. So, I decided to write a CodeIgniter authentication library from scratch. Now, I have to make design decision about how to determine whether one user is login. Basically, after user input username & password pair. A cookie is set for this session, following navigations in the web application will not require username & password. The server side will check whether the session cookie is valid to determine whether current user is login. The question is: how to determine whether cookie is valid cookie issued from server side? I can image the most simple way is to have the cookie value stored in session status as well. For each HTTP request, compare the value from cookie and the value from server session. (Since CodeIgniter session library store session variables in cookies, it is not applicable without some tweak.) This method requires storage in server side. For huge web application that is deployed in multiple datacenters. It is possible that user input username & password when browsing in one datacenter, while he/she access the web application in another datacenter later. The expected behavior is that user just input username & password once. As a result, all datacenters should be able to access the session status. That is possible not applicable even the session status is stored in external storage such as database. I tried Google. I login Google with Asian proxy which is supposed to direct me to datacenters in Asian. Then I switch to North American proxy which should direct me to datacenters in North America. It recognize my login without asking username and password again. So, is there any way to determine whether user is login without server side session status?

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