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  • PHP: Array of objects is empty when I come to retrieve one from the array

    - by Tom
    Good morning, I am trying to load rows from a database and then create objects from them and add these objects to a private array. Here are my classes: <?php include("databaseconnect.php"); class stationItem { private $code = ''; private $description = ''; public function setCode($code ){ $this->code = $code; } public function getCode(){ return $this->code; } public function setDescription($description){ $this->description = $description; } public function getDescription(){ return $this->description; } } class stationList { private $stationListing; function __construct() { connect(); $stationListing = array(); $result = mysql_query('SELECT * FROM stations'); while ($row = mysql_fetch_assoc($result)) { $station = new stationItem(); $station->setCode($row['code']); $station->setDescription($row['description']); array_push($stationListing, $station); } mysql_free_result($result); } public function getStation($index){ return $stationListing[$index]; } } ?> As you can see I am creating a stationItem object per database row (which for now has a code and description) and I then push these on to the end of my array which is held as a private variable in stationList. This is code which creates this classes and attempts to access the properties on them: $stations = new stationList(); $station = $stations->getStation(0); echo $station->getCode(); I am finding that the sizeof($stationList) at the end of the constructor is 1 but then it is zero when we come to try to get an object from the array using the index. Therefore the error that I get is: Fatal error: Call to a member function getCode() on a non-object Please can someone explain to me why this is happening? I guess I am misunderstanding how object references work in PHP5.

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  • PLKs and Web Service Software Factory

    - by Nix
    We found a bug in Web Service Software Factory a description can be found here. There has been no updates on it so we decided to download the code and fix it ourself. Very simple bug and we patched it with maybe 3 lines of code. However* we have now tried to repackage it and use it and are finding that this is seemingly an impossible process. Can someone please explain to me the process of PLKs? I have read all about them but still don't understand what is really required to distribute a VS package. I was able to get it to load and run using a PLK obtained from here, but i am assuming that you have to be a partner to get a functional PLK that will be recognized on other peoples systems? Every time i try and install this on a different computer I get a "Package Load Failure". Is the reason I am getting errors because I am not using a partner key? Is there any other way around this? For instance is there any way we can have an "internal" VS package that we can distribute? Edit Files I had to change to get it to work. First run devenv PostInstall.proj Generate your plks and replace ##Package PLK## (.resx files) --Just note that package version is not the class name but is "Web Service Software Factory: Modeling Edition" -- And you need to remove the new lines from the key ProductDefinitionRegistryFragment.wxi line 1252(update version to whatever version you used in plk) Uncomment all // [VSShell::ProvideLoadKey("Standard", Constant in .tt files.

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  • what is the exact way to use Endorsed directory in jdk1.6

    - by raticulin
    I want to upgrade my jaxws to 2.2 (jdk1.6 comes bundled with jaxws 2.1). My jdk is (I did not install public jre): java version "1.6.0_20" Java(TM) SE Runtime Environment (build 1.6.0_20-b02) Java HotSpot(TM) Client VM (build 16.3-b01, mixed mode) In jaxws' own doc they explain how to do it: One way to fix this is to copy jaxws-api.jar and jaxb-api.jar into JRE endorsed directory, which is $JAVA_HOME/lib/endorsed (or $JDK_HOME/jre/lib/endorsed) But I am not sure this is having any effect in my installation. For starters I have only defined %JAVA_HOME%. And folder $JAVA_HOME/lib/endorsed is inexistant, so I created and copied the two jars. But if I do (wsgen is a tool from jaxws) wsgen -version I still get: JAX-WS RI 2.1.6 in JDK 6 I also tried creating folder JAVA_HOME\jre\lib\endorsed (notice that in the doc they say JDK_HOME, but as I only have JAVA_HOME I used this path). Still same wsgen output. My questions are: What is the difference between JAVA_HOME and JDK_HOME in the doc page? anything significant or just two ways to refer to JAVA_HOME ? Is 'wsgen -version' a valid way to check jaxws version that is used or this always calls the exe in the original jdk, but it does not mean endorsed jars will be used? Anyone knows very detailed steps to install jaxws2.2 in a jdk.16?

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  • SeriesInterpolate - removing data at start of array

    - by Allan Jardine
    Hello all, I've been experimenting with Flex Charts (in Flash Builder 4) recently, but have run into one area which didn't quite work as I was expecting. Specifically, when adding and removing a data point from an array, with SeriesInterpolate set. I've put up three examples, as I expect these will make a lot more sense than me trying to explain it with words only!: http://sprymedia.co.uk/media/misc/flex/linechart/LineChart-Add.swf - Clicking the button in the top right adds a new data point to the end of the data array, and the chart is smoothly updated (almost smoothly there is a 1px shift when animating which is odd...) http://sprymedia.co.uk/media/misc/flex/linechart/LineChart-Delete.swf - Clicking the button (which is now labelled incorrectly) will remove the item at the start of the data array - but the chart draws this as if it were removing the end element. http://sprymedia.co.uk/media/misc/flex/linechart/LineChart-AddDelete.swf - This is sort of what I'm eventually aiming for - a smooth side scroll chart, where new data is added at the end and the old data is sifted off the front. However the delete behaviour makes this look a bit odd. Does anyone know if there is a way to get the smooth transition I'm looking with SeriesInterpolate? Or is it possible to implement a custom transition? Many thanks, Allan

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  • Tracking iPhone on Yahoo Web Analytics using ASIHTTPRequest

    - by Mads Mobæk
    I'm trying to track an event in my app using Yahoo Web Analytics. The code I am using looks like ASIHTTPRequest *yahooTrack = [ASIHTTPRequest requestWithURL: [NSURL URLWithString:@"http://s.analytics.yahoo.com/p.pl?a=xxxxxxxxxxxxx&js=no&b=yyyyyyyyyyyy&cf6=zzzzzzzzzzz"]]; yahooTrack.didFinishSelector = @selector(statisticsFinished:); yahooTrack.delegate = self; [yahooTrack startAsynchronous]; Then the statisticsFinished looks like: NSLog(@"Cookies: %@", request.requestCookies); NSLog(@"Redircount: %d", [request redirectCount]); NSLog(@"Responsecode %d %@\nMsg: %@", request.responseStatusCode, request.responseStatusMessage, [request responseString]); And all the information I get back looks correct. Cookies are set, redirectcount is 1 the first time (as it redirects to s.analytics.yahoo.com/itr.pl?.... a normal browser does). Then the redirectcount is 0 for subsequent request until the app is restarted and session cleared. The responseString returns GIF89a. Even if the data looks correct, Yahoo still won't track. As soon as I call the tracking url directly in my browser it works as expected. I realize Flurry is a better option, but I'm forced to use Yahoo in this case. Also, using a UIWebView probably would work, but I'm against putting in a webview just for tracking purposes. Is there any difference in how ASIHTTPRequest and Safari would handle a call to a simple URL as this? Or do you see anything else that could explain why the tracking isn't working?

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  • Why does VBA Find loop fail when called from Evaluate?

    - by Abiel
    I am having some problems running a find loop inside of a subroutine when the routine is called using the Application.Evaluate or ActiveSheet.Evaluate method. For example, in the code below, I define a subroutine FindSub() which searches the sheet for a string "xxx". The routine CallSub() calls the FindSub() routine using both a standard Call statement and Evaluate. When I run Call FindSub, everything will work as expected: each matching address gets printed out to the immediate window and we get a final message "Finished up" when the code is done. However, when I do Application.Evaluate "FindSub()", only the address of the first match gets printed out, and we never reach the "Finished up" message. In other words, an error is encountered after the Cells.FindNext line as the loop tries to evaluate whether it should continue, and program execution stops without any runtime error being printed. I would expect both Call FindSub and Application.Evaluate "FindSub()" to yield the same results in this case. Can someone explain why they do not, and if possible, a way to fix this? Thanks. Note: In this example I obviously do not need to use Evaluate. This version is simplified to just focus on the particular problem I am having in a more complex situation. Sub CallSub() Call FindSub Application.Evaluate "FindSub()" End Sub Sub FindSub() Dim rngFoundCell As Range Dim rngFirstCell As Range Set rngFoundCell = Cells.Find(What:="xxx", after:=ActiveCell, LookIn:=xlValues, _ LookAt:=xlPart, SearchOrder:=xlByRows, SearchDirection:=xlNext, _ MatchCase:=False, SearchFormat:=False) If Not rngFoundCell Is Nothing Then Set rngFirstCell = rngFoundCell Do Debug.Print rngFoundCell.Address Set rngFoundCell = Cells.FindNext(after:=rngFoundCell) Loop Until (rngFoundCell Is Nothing) Or (rngFoundCell.Address = rngFirstCell.Address) End If Debug.Print "Finished up" End Sub

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  • Newbie database index question

    - by RenderIn
    I have a table with multiple indexes, several of which duplicate the same columns: Index 1 columns: X, B, C, D Index 2 columns: Y, B, C, D Index 3 columns: Z, B, C, D I'm not very knowledgeable on indexing in practice, so I'm wondering if somebody can explain why X, Y and Z were paired with these same columns. B is an effective date. C is a semi-unique key ID for this table for a specific effective date B. D is a sequence that identifies the priority of this record for the identifier C. Why not just create 6 indexes, one for each X, Y, Z, B, C, D? I want to add an index to another column T, but in some contexts I'll only be querying on T alone while in others I will also be specifying the B, C and D columns... so should I create just one index like above or should I create one for T and one for (T, B, C, D)? I've not had as much luck as expected when googling for comprehensive coverage of indexing. Any resources where I can get a through explanation and lots of examples of B-tree indexing?

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  • Help to understand the issue with protected method

    - by zeroed
    I'm reading Sybex Complete Java 2 Certification Study Guide April 2005 (ISBN0782144195). This book is for java developers who wants to pass java certification. After a chapter about access modifiers (along with other modifiers) I found the following question (#17): True or false: If class Y extends class X, the two classes are in different packages, and class X has a protected method called abby(), then any instance of Y may call the abby() method of any other instance of Y. This question confused me a little. As far as I know you can call protected method on any variable of the same class (or subclasses). You cannot call it on variables, that higher in the hierarchy than you (e.g. interfaces that you implement). For example, you cannot clone any object just because you inherit it. But the questions says nothing about variable type, only about instance type. I was confused a little and answered "true". The answer in the book is False. An object that inherits a protected method from a superclass in a different package may call that method on itself but not on other instances of the same class. There is nothing here about variable type, only about instance type. This is very strange, I do not understand it. Can anybody explain what is going on here?

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  • Determining which form input failed validation?

    - by Alastair Pitts
    I am designing a creation wizard in ASP.NET MVC 1 and instead of posting back each step, I'm using javascript to toggle the display of the different steps divs. This is a quick sample of the code, just to explain. <% using (Html.BeginForm()) {%> <fieldset> <legend>Fields</legend> <div id="wizardStep1"> <% Html.RenderPartial("CreateStep1", Model); %> </div> <div id="wizardStep2"> <% Html.RenderPartial("CreateStep2", Model); %> </div> <div id="wizardStep3"> <% Html.RenderPartial("CreateStep3", Model); %> </div> </fieldset> <% } %> I have javascript that just toggles the visibility of the divs, with each partial view containing a different section of the input form (which is pretty large by itself) My question is, if the form fails validation and I reload the page with the validation errors, is there a way for me to determine which div contains the error? Either in javascript or other? Failing that, is there a good client-side validation library for MVC 1? Ideally I'd love to move to MVC2 and the client side validation built into that, but I am required to use MVC1

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  • Button Click Event Getting Lost

    - by AlishahNovin
    I have a Menu and Submenu structure in Silverlight, and I want the submenu to disappear when the parent menu item loses focus - standard Menu behavior. I've noticed that the submenu's click events are lost when a submenu item is clicked, because the parent menu item loses focus and the submenu disappears. It's easier to explain with code: ParentMenuBtn.Click += delegate { SubMenu.Visibility = (SubMenu.Visibility == Visibility.Visible) ? SubMenu.Collapsed : SubMenu.Visible; }; ParentMenuBtn.LostFocus += delegate { SubMenu.Visibility = Visibility.Collapsed; }; SubMenuBtn.Click += delegate { throw new Exception("This will never be thrown."); }; In my example, when SubMenuBtn is clicked, the first event that triggers is ParentMenuBtn.LostFocus(), which hides the container of SubMenuBtn. Once the container's visibility collapses, the Click event is never triggered. I'd rather avoid having to hide the sub-menu each time, but I'm a little surprised that the Click event is never triggered as a result... I can't put any checks inside the LostFocus() event to see if my SubMenuBtn has focus, because it does not gain focus until after the LostFocus() event is called. In other words, SubMenuBtn.IsFocused = false when LostFocus() is triggered. Anyone have any thoughts about this?

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  • Linux 2.6.31 Scheduler and Multithreaded Jobs

    - by dsimcha
    I run massively parallel scientific computing jobs on a shared Linux computer with 24 cores. Most of the time my jobs are capable of scaling to 24 cores when nothing else is running on this computer. However, it seems like when even one single-threaded job that isn't mine is running, my 24-thread jobs (which I set for high nice values) only manage to get ~1800% CPU (using Linux notation). Meanwhile, about 500% of the CPU cycles (again, using Linux notation) are idle. Can anyone explain this behavior and what I can do about it to get all of the 23 cores that aren't being used by someone else? Notes: In case it's relevant, I have observed this on slightly different kernel versions, though I can't remember which off the top of my head. The CPU architecture is x64. Is it at all possible that the fact that my 24-core jobs are 32-bit and the other jobs I'm competing w/ are 64-bit is relevant? Edit: One thing I just noticed is that going up to 30 threads seems to alleviate the problem to some degree. It gets me up to ~2100% CPU.

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  • Should we have a database independent SQL like query language in Django? [closed]

    - by Yugal Jindle
    Note : I know we have Django ORM already that keeps things database independent and converts to the database specific SQL queries. Once things starts getting complicated it is preferred to write raw SQL queries for better efficiency. When you write raw sql queries your code gets trapped with the database you are using. I also understand its important to use the full power of your database that can-not be achieved with the django orm alone. My Question : Until I use any database specific feature, why should one be trapped with the database. For instance : We have a query with multiple joins and we decided to write a raw sql query. Now, that makes my website postgres specific. Even when I have not used any postgres specific feature. I feel there should be some fake sql language which can translate to any database's sql query. Even Django's ORM can be built over it. So, that if you go out of ORM but not database specific - you can still remain database independent. I asked the same question to Jacob Kaplan Moss (In person) : He advised me to stay with the database that I like and endure its whole power, to which I agree. But my point was not that we should be database independent. My point is we should be database independent until we use a database specific feature. Please explain, why should be there a fake sql layer over the actual sql ?

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  • Core Data NSPredicate to filter results

    - by Bryan
    I have a NSManagedObject that contains a bID and a pID. Within the set of NSManagedObjects, I only want a subset returned and I'm struggling to find the correct NSPredicate or way to get what I need out of Core Data. Here's my full list: bid pid 41 0 42 41 43 0 44 0 47 41 48 0 49 0 50 43 There is a parent-child relationship above. Rules: If a record's PID = 0, it means that that record IS a parent record. If a record's PID != 0, then that record's PID refers to it's parent record's BID. Example: 1) BID = 41 is a parent record. Why? Because records BID=42 and record BID=47 have PID's of 41, meaning those are children of its PID record. 2) BID = 42 has a parent record with a BID = 41. 3) BID = 43 is a parent record. 4) BID = 44 is a parent record. 5) BID = 47 has a parent record with a BID = 41 because its PID = 41. See #1 above. 6) BID = 48 is a parent record. 7) BID = 49 is a parent record. 8) BID = 50 is a child record, and its parent record has a BID = 43. See the pattern? Now, basically from that, I want only the following rows fetched: bid pid 44 0 47 41 48 0 49 0 50 43 BID = 41, BID = 48, BID = 49 should all be returned because there are no records with a PID equal to their BID. BID = 47 should be returned because it is the most recent child of PID = 41. BID = 50 should be returned because it is the most recent child of PID = 43. Hope this helps explain it more.

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  • Flexible Decorator Pattern?

    - by Omar Kooheji
    I was looking for a pattern to model something I'm thinking of doing in a personal project and I was wondering if a modified version of the decorator patter would work. Basicly I'm thinking of creating a game where the characters attributes are modified by what items they have equiped. The way that the decorator stacks it's modifications is perfect for this, however I've never seen a decorator that allows you to drop intermediate decorators, which is what would happen when items are unequiped. Does anyone have experience using the decorator pattern in this way? Or am I barking up the wrong tree? Clarification To explain "Intermediate decorators" if for example my base class is coffe which is decorated with milk which is decorated with sugar (using the example in Head first design patterns) milk would be an intermediate decorator as it decorates the base coffee, and is decorated by the sugar. Yet More Clarification :) The idea is that items change stats, I'd agree that I am shoehorning the decorator into this. I'll look into the state bag. essentially I want a single point of call for the statistics and for them to go up/down when items are equiped/unequiped. I could just apply the modifiers to the characters stats on equiping and roll them back when unequiping. Or whenever a stat is asked for iterate through all the items and calculate the stat. I'm just looking for feedback here, I'm aware that I might be using a chainsaw where scissors would be more appropriate...

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  • Sorting an array of Doubles with NaN in it

    - by Agent Worm
    This is more of a 'Can you explain this' type of question than it is anything else. I came across a problem at work where we were using NaN values in a table, but when the table was sorted, it came out in a very strange, strange manner. I figured NaN was mucking up something so I wrote up a test application to see if this is true. This is what I did. static void Main(string[] args) { double[] someArray = { 4.0, 2.0, double.NaN, 1.0, 5.0, 3.0, double.NaN, 10.0, 9.0, 8.0 }; foreach (double db in someArray) { Console.WriteLine(db); } Array.Sort(someArray); Console.WriteLine("\n\n"); foreach (double db in someArray) { Console.WriteLine(db); } Console.ReadLine(); } Which gave the result: Before: 4,2,NaN,1,5,3,NaN,10,9,8 After: 1,4,NaN,2,3,5,8,9,10,NaN So yes, the NaN some how made the sorted array to be sorted in a strange way. To quote Fry; "Why is those things?"

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  • accepts_nested_attributes_for and nested_form plugin

    - by Denis
    Hi folks, I've the following code in a _form.html.haml partial, it's used for new and edit actions. (fyi I use the Ryan Bates' plugin nested_form) .fields - f.fields_for :transportations do |builder| = builder.collection_select :person_id, @people, :id, :name, {:multiple => true} = builder.link_to_remove 'effacer' = f.link_to_add "ajouter", :transportations works fine for the new action... for the edit action, as explain in the doc, I've to add the :id of already existing associations, so, I've to add something like = builder.hidden_field :id, ?the value? if ?.new_record? How can I get the value? Here is the doc of accepts_nested_attributes_for for reference (source: http://github.com/rails/rails/blob/master/activerecord/lib/active_record/nested_attributes.rb#L332) # Assigns the given attributes to the collection association. # # Hashes with an <tt>:id</tt> value matching an existing associated record # will update that record. Hashes without an <tt>:id</tt> value will build # a new record for the association. Hashes with a matching <tt>:id</tt> # value and a <tt>:_destroy</tt> key set to a truthy value will mark the # matched record for destruction. # # For example: # # assign_nested_attributes_for_collection_association(:people, { # '1' => { :id => '1', :name => 'Peter' }, # '2' => { :name => 'John' }, # '3' => { :id => '2', :_destroy => true } # }) # # Will update the name of the Person with ID 1, build a new associated # person with the name `John', and mark the associatied Person with ID 2 # for destruction. # # Also accepts an Array of attribute hashes: # # assign_nested_attributes_for_collection_association(:people, [ # { :id => '1', :name => 'Peter' }, # { :name => 'John' }, # { :id => '2', :_destroy => true } # ]) Thanks for your help.

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  • What is the behavior of a WPF 4 ControlStoryboardAction trigger?

    - by jonathan_ou
    Hi all! I have a question that's been bugging me for a while: I have a lengthy IO operation which I invoke asynchronously, and I want my UI to show a blinking text to tell the users that the data is loading. I have an IsLoading boolean property in my ViewModel, and I used a ControlStoryboardAction to kickoff the blinking animation, which is set to repeat forever. For my ControlStoryboardAction trigger, I configured a data trigger to see if IsLoading is true, and start my storyboard if true. My problem is, when my IO operation returns, and I set IsLoading back to false, the animation continues to play. I thought once the trigger condition evaluated to false, it would stop the animation? I then added a second ControlStoryboardAction to stop the animation if IsLoading evaluted to false, but this didn't have any effect. The animation continued to play after IsLoading was false. Can anyone explain to me how trigger works in ControlStoryboardAction? In normal data triggers in WPF, once the condition evaluated to false, the property would be set back to its original state. It seems triggers in WPF actions don't work the same way? Thanks in advance for your help!

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  • Flash gets XML but the values are wrong, as3

    - by VideoDnd
    Flash receives the XML, but the values are wrong. How do I fix this? Problem I can see the XML loaded with no errors, but my output is way off. It's as though it's not receiving any values. Numbers in the output window and animation move rapidly. The Flash file runs as if it's variables where set to zero. I changed the order of my code, but that didn't help with this. Please explain how I can correct this. SWF //load xml var myXML:XML; var myLoader:URLLoader = new URLLoader(); myLoader.load(new URLRequest("xml.xml")); myLoader.addEventListener(Event.COMPLETE, processXML); //parse XML function processXML(e:Event):void { myXML = new XML(e.target.data); trace(myXML); //receive values from XML delay = parseInt(myXML.DELAY.text()); trace(delay); repeat = parseInt(myXML.REPEAT.text()); trace(repeat); } //variables var delay:uint = 0; var repeat:uint = 0; //timer and event var timer:Timer = new Timer(uint(delay),uint(repeat)); timer.addEventListener(TimerEvent.TIMER, countdown); //counter function countdown(event:TimerEvent) { myText.text = String(0 + timer.currentCount); trace(0 + timer.currentCount); } timer.start(); XML <?xml version="1.0" encoding="utf-8"?> <SESSION> <DELAY TITLE="starting position">1000</DELAY> <REPEAT TITLE="starting position">60</REPEAT> </SESSION>

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  • C - Complicated pointer declarations - help understanding

    - by Emmel
    In my burgeoning new self-education in the C language, I've come across a set of declarations that I do not understand how to read. I'd love for someone to break these down. I'll explain at the bottom where I got these examples from. 1. char (*(*x())[])() "x: function returning pointer to array[] of pointer to function returning char" - huh? 2. char (*(*x[3])())[5] "x: array[3] of pointer to function returning pointer to array[5] of char" - come again? 3. char **argv This I understand. "Pointer to pointer to char." But what I don't understand is -- what's the use case for a pointer to a pointer? Follow-up question: does anyone every use declarations this complex or is this just academic fun on the part of the authors of the examples I got this from? These examples are from section 5.12 of the K&R book. This is the first time I'm genuinely stumped by an explanation, in an otherwise well-written classic. Thanks.

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  • std::binary_function - no match for call?

    - by Venkat Shiva
    Hi, this is my code: #include <iostream> #include <functional> using namespace std; int main() { binary_function<double, double, double> operations[] = { plus<double>(), minus<double>(), multiplies<double>(), divides<double>() }; double a, b; int choice; cout << "Enter two numbers" << endl; cin >> a >> b; cout << "Enter opcode: 0-Add 1-Subtract 2-Multiply 3-Divide" << endl; cin >> choice; cout << operations[choice](a, b) << endl; } and the error I am getting is: Calcy.cpp: In function ‘int main()’: Calcy.cpp:17: error: no match for call to ‘(std::binary_function<double, double, double>) (double&, double&)’ Can anyone explain why I am getting this error and how to get rid of it?

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  • AStar in a specific case in C#

    - by KiTe
    Hello. To an intership, I have use the A* algorithm in the following case : the unit shape is a square of height and width of 1, we can travel from a zone represented by a rectangle from another, but we can't travel outside these predifined areas, we can go from a rectangle to another through a door, represented by a segment on corresponding square edge. Here are the 2 things I already did but which didn't satisfied my boss : 1 : I created the following classes : -a Door class which contains the location of the 2 separated squares and the door's orientation (top, left, bottom, right), -a Map class which contains a door list, a rectangle list representing the walkable areas and a 2D array representing the ground's squares (for additionnal infomations through an enumeration) - classes for the A* algorithm (node, AStar) 2 : -a MapCase class, which contains information about the case effect and doors through an enumeration (with [FLAGS] attribute set on, to be able to cummulate several information on each case) -a Map classes which only contains a 2D array of MapCase classes - the classes for the A* algorithm (still node an AStar). Since the 2 version is better than the first (less useless calculation, better map classes architecture), my boss is not still satisfied about my mapping classes architecture. The A* and node classes are good and easily mainainable, so I don't think I have to explain them deeper for now. So here is my asking : has somebody a good idea to implement the A* with the problem specification (rectangle walkable but with a square unit area, travelling through doors)? He said that a grid vision of the problem (so a 2D array) shouldn't be the correct way to solve the problem. I wish I've been clear while exposing my problem .. Thanks KiTe

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  • Understanding evaluation of expressions containing '++' and '->' operators in C.

    - by Leif Ericson
    Consider this example: struct { int num; } s, *ps; s.num = 0; ps = &s; ++ps->num; printf("%d", s.num); /* Prints 1 */ It prints 1. So I understand that it is because according to operators precedence, -> is higher than ++, so the value ps->num (which is 0) is firstly fetched and then the ++ operator operates on it, so it increments it to 1. struct { int num; } s, *ps; s.num = 0; ps = &s; ps++->num; printf("%d", s.num); /* Prints 0 */ In this example I get 0 and I don't understand why; the explanation of the first example should be the same for this example. But it seems that this expression is evaluated as follows: At first, the operator ++ operates, and it operates on ps, so it increments it to the next struct. Only then -> operates and it does nothing because it just fetches the num field of the next struct and does nothing with it. But it contradicts the precedence of operators, which says that -> have higher precedence than ++. Can someone explain this behavior? Edit: After reading two answers which refer to a C++ precedence tables which indicate that a prefix ++/-- operators have lower precedence than ->, I did some googling and came up with this link that states that this rule applies also to C itself. It fits exactly and fully explains this behavior, but I must add that the table in this link contradicts a table in my own copy of K&R ANSI C. So if you have suggestions as to which source is correct I would like to know. Thanks.

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  • asyncsocket Write Issue

    - by James
    I am attempting to use asyncsocket to communicate GPS data from a server app on my iPhone to a client app on my macbook. The two devices connect without any problems, and when the first data is sent from the iPhone to the laptop in asyncsocket's didConnectToHost method, the data is sent without hiccup. When I subsequently try to write additional data to the laptop from the locationManager method, however, no data is written. Here is the code: - (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation { lat = [NSNumber numberWithFloat:newLocation.coordinate.latitude]; [lat retain]; NSLog(@"lat: %1.0f", [lat floatValue]); NSString *msg = [NSString stringWithFormat:@"%1.0f", [lat floatValue]]; NSData *msgData = [msg dataUsingEncoding:NSUTF8StringEncoding]; [listenSocket writeData:msgData withTimeout:-1 tag:0]; } listensocket is my instance of ASyncSocket. I know that no data is being sent because after the initial successful transfer, the didWriteDataWithTag method is not called. Can anyone explain this? Thanks! James

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  • How to use SQLAlchemy to dump an SQL file from query expressions to bulk-insert into a DBMS?

    - by Mahmoud Abdelkader
    Please bear with me as I explain the problem, how I tried to solve it, and my question on how to improve it is at the end. I have a 100,000 line csv file from an offline batch job and I needed to insert it into the database as its proper models. Ordinarily, if this is a fairly straight-forward load, this can be trivially loaded by just munging the CSV file to fit a schema, but I had to do some external processing that requires querying and it's just much more convenient to use SQLAlchemy to generate the data I want. The data I want here is 3 models that represent 3 pre-exiting tables in the database and each subsequent model depends on the previous model. For example: Model C --> Foreign Key --> Model B --> Foreign Key --> Model A So, the models must be inserted in the order A, B, and C. I came up with a producer/consumer approach: - instantiate a multiprocessing.Process which contains a threadpool of 50 persister threads that have a threadlocal connection to a database - read a line from the file using the csv DictReader - enqueue the dictionary to the process, where each thread creates the appropriate models by querying the right values and each thread persists the models in the appropriate order This was faster than a non-threaded read/persist but it is way slower than bulk-loading a file into the database. The job finished persisting after about 45 minutes. For fun, I decided to write it in SQL statements, it took 5 minutes. Writing the SQL statements took me a couple of hours, though. So my question is, could I have used a faster method to insert rows using SQLAlchemy? As I understand it, SQLAlchemy is not designed for bulk insert operations, so this is less than ideal. This follows to my question, is there a way to generate the SQL statements using SQLAlchemy, throw them in a file, and then just use a bulk-load into the database? I know about str(model_object) but it does not show the interpolated values. I would appreciate any guidance for how to do this faster. Thanks!

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  • MIDP 2.0 version issues: $method is undefined for $type

    - by Kilnr
    Hi, I've written a MIDlet that does several "advanced" things: fetching images from the web, resizing them, saving them on the phone, displaying them. This all works perfectly in the Nokia S60 3rd Edition FP1 emulator. This device has MIDP 2.0 and CLDC 1.1 support (also JSR75, which I need in order to save files). It also works as it should on the Nokia E71 (physical device). I then tried to run the MIDlet on several other emulators. One of them, the DefaultCldcJtwiPhone2 from the Java ME SDK 3.0, also claims MIDP 2.0 and CLDC 1.1 support. It doesn't have JSR75, which explains why "FileConnection can not be resolved to a type". This does not, however, explain why List.deleteAll(), String.equalsIgnoreCase(String) and a few others are undefined. The actual errors that I get: The method ceil(double) is undefined for the type Math The method deleteAll() is undefined for the type List The method equalsIgnoreCase(String) is undefined for the type String The method getWidth() is undefined for the type Displayable When I look at the MIDP 2.0 (i.e. JSR118) API (http://java.sun.com/javame/reference/apis/jsr118/), I can clearly see all of these methods being present, with the "since" tag being either MIDP 2.0 or CLDC 1.1. My question: why doesn't an emulator with MIDP 2.0 support have access to all MIDP 2.0 methods? Or alternatively, what am I doing wrong?

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