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  • Why does accessing a member of a malloced array of structs seg fault?

    - by WSkinner
    I am working through Learn C The Hard Way and am stumped on something. I've written a simplified version of the problem I am running into to make it easier to get down to it. Here is the code: #include <stdlib.h> #define GROUP_SIZE 10 #define DATA_SIZE 64 struct Dummy { char *name; }; struct Group { struct Dummy **dummies; }; int main() { struct Group *group1 = malloc(sizeof(struct Group)); group1->dummies = malloc(sizeof(struct Dummy) * GROUP_SIZE); struct Dummy *dummy1 = group1->dummies[3]; // Why does this seg fault? dummy1->name = (char *) malloc(DATA_SIZE); return 0; } when I try to set the name pointer on one of my dummies I get a seg fault. Using valgrind it tells me this is uninitialized space. Why is this?

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  • HttpService Vs Remote Objects

    - by kalyaniRavi
    Hi, I have a flex application and need to show the real time data into the chatrs and datagrids. Eralier we are used Httpservices to showing the real time data and historical data into charts and datagrids. But now we are going to replace the Httpservices to remote objects. So which places generally need to change. I have a little bit idea about remote objects. Thanks, Ravi

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  • Adding files to the DPR file vs project paths in Delphi 2010

    - by Robert McCabe
    We are just migrating from D7 to D2010 and are having a debate about cleaning up the project paths. We have a number of directories with a large number of Pas files that are included on some project paths, but only a few of the files are actually used by any single project. One option is to eliminate the project paths completely and only have all used files in the dpr. The second option is to keep only the needed files in the dpr and have project paths to the directories for the rest of the files. Is there any argument for one option over the other?

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  • xgettext vs gettext

    - by Kentor
    I have a few questions: I know what gettext is. I've read a few posts where they mentioned xgettext and was curious as to what is the difference between the two. How can I install xgettext on Windows? And finally, does anybody have a tutorial on how to install the library php-gettext http://savannah.nongnu.org/projects/php-gettext/ (this one usually doesn't come with PHP) I've read about it in an article but I'm not sure how to get it working in Windows. The thing is, sometimes when you make changes, you need to restart Apache to see the new data with the gettext that comes with PHP (but with the library you don't need to restart it) so I wanted to use the library for development. Thanks!

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  • NSArray vs. SQLite for Complex Queries on iPhone

    - by GingerBreadMane
    Developing for iPhone, I have a collection of points that I need to make complex queries on. For example: "How many points have a y-coordinate of 10" and "Return all points with an X-coordinate between 3 and 5 and a y-coordinate of 7". Currently, I am just cycling through each element of an NSArray and checking to see if each element matches my query. It's a pain to write the queries though. SQLite would be much nicer. I'm not sure which would be more efficient though since a SQLite database resides on disk and not in memory (to my understanding). Would SQLite be as efficient or more efficient here? Or is there a better way to do it other than these methods that I haven't thought of? I would need to perform the multiple queries with multiple sets of points thousands of times, so the best performance is important.

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  • Timer vs setTimeout

    - by Christophe Herreman
    The docs for flash.utils.setTimeout() state: Instead of using this method, consider creating a Timer object, with the specified interval, using 1 as the repeatCount parameter (which sets the timer to run only once). Does anyone know if there is a (significant) advantage in doing so? Using setTimeout is a lot easier when you only need to delay 1 call.

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  • Laravel - Mail class Exception

    - by Christian Giupponi
    I need to send email within my app and this is my code: if( $agent->save() ) { //Preparo la mail da inviare con i dati di login $data = [ 'nome' => $input['nome'], 'cognome' => $input['cognome'], 'email' => $input['email'], 'password' => $input['password'] ]; //ATTENZIONE //Questo è da rimuovere in produzione, finge di inviare la mail Mail::pretend(); //Recuero il template e passo alla funzione i dati Mail::send('emails.agents.registration', $data, function($message) use ($data) { $message->to( $data['email'], $data['nome'].' '.$data['cognome'] )->subject('Benvenuto!'); }); return Redirect::action('admin.agents.index')->with('positive_flash_message', 'Agente inserito correttamente.'); } As you can see I have use the Mail::pretend to avoid the email send in development, the problem is that I get this error every time I try to send an email: Undefined property: Illuminate\Mail\Message::$email (View: /var/www/progetti/app/views/emails/agents/registration.blade.php) nd this is my blade view: Email: {{ $message->email }} Password: {{ $message->password }} What's wrong with $message?

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  • C vs. C++ for performance in memory allocation

    - by Andrei
    Hi, I am planning to participate in development of a code written in C language for Monte Carlo analysis of complex problems. This codes allocates huge data arrays in memory to speed up its performance, therefore the author of the code has chosen C instead of C++ claiming that one can make faster and more reliable (concerning memory leaks) code with C. Do you agree with that? What would be your choice, if you need to store 4-16 Gb of data arrays in memory during calculation?

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  • How to access class member from bison action

    - by yodhevauhe
    I am calling yyparse from a member function. How to access the member variables/function from the bison action. I am currently doing as %{ #include "myclass.h" #include "parse.tab.hh" MyClass *ptr=NULL; void MyClass::evaluate(string expression) { ptr=this; yy_scan_string(expression.c_str()); yyparse(); } %} %% EXPR : EXPR PLUS EXPR { $$ = ptr->memberFunction("+",$1,$3); }

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  • How to call another class's method from my app delegate

    - by Jared
    I have an application that utilizes UILocalNotifications to pop-up UIAlertViews. When the notification fires, the user chooses to go into the app, and this method is called from my app delegate: - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {...} Where I can handle it and where I also prompt another alertview for more information. So when the app launches, it is displaying view A, and then the alertview pops up and prompts for input. This alertview, however, is originating from my app delegate. I need to be able to reload view A when the user hits Yes/No on the alertview. How can I do that from within my app delegate? Any help is appreciated!!

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  • Ruby/Rails - Add records to an object with each loop iteration / Object vs Arrays

    - by ChrisWesAllen
    I'm trying to figure out how to add records to an existing object for each iteration of a loop. I'm having a hard time discovering the difference between an object and an array. I have this @events = Event.find(1) @loops = Choices.find(:all, :limit => 5) #so loop for 5 instances of choice model for loop in @loops @events = Event.find(:all,:conditions => ["event.id = ?", loop.event_id ]) end I'm trying to add a new events to the existing @events object based on the id of whatever the loop variable is. But the ( = ) operator just creates a new instance of the @events object. I tried ( += ) and ( << ) as operators but got the error "You have a nil object when you didn't expect it! You might have expected an instance of Array. The error occurred while evaluating nil" I tried created an array events = [] events << Event.find(1) @loops = Choices.find(:all, :limit => 5) #so loop for 5 instances of choice model for loop in @loops events << Event.find(:all,:conditions => ["event.id = ?", loop.event_id ]) end But I dont know how to call that arrays attributes within the view With objects I was able do create a loop within the view and call all the attributes of that object as well... <table> <% for event in @events %> <tr> <td><%= link_to event.title, event %></td> <td><%= event.start_date %></td> <td><%= event.price %></td> </tr> <% end %> </table> How could i do this with an array set? So the questions are 1) Whats the difference between arrays and objects? 2) Is there a way to add into the existing object for each iteration? 3) If I use an array, is there a way to call the attributes for each array record within the view?

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  • Getting all types from an assembly derived from a base class

    - by CaptnCraig
    I am trying to examine the contents of an assembly and find all classes in it that are directly or indirectly derived from Windows.Forms.UserControl. I am doing this: Assembly dll = Assembly.LoadFrom(filename); var types = dll.GetTypes().Where(x => x.BaseType == typeof(UserControl)); But it is giving an empty list because none of the classes directly extend UserControl. I don't know enough about reflection to do it quickly, and I'd rather not write a recursive function if I don't have to.

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  • Getting below error when trying to register a generic class with a implementation using .net 2.0

    - by Gaurav Saxena
    Code: StructureMapConfiguration.BuildInstancesOf().AsSingletons().TheDefaultIsConcreteType(); Error: StructureMap Exception Code: 190 Can not create a Generic PluginFamily for PluginFamily MIGExcel.Service.IPersistenceService1[[MIGExcel.Model.Contact, WizardModel, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]. Check that the basic type MIGExcel.Service.IPersistenceService1 is configured as a PluginFamily. These Generic types are configured within StructureMap as PluginFamily's: MIGExcel.Service.IPersistenceService`1[[MIGExcel.Model.Contact, WizardModel, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]],MIGExcel.Service;

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  • Accessing property of object vs variable in javascript

    - by Samuel
    Why when I try to access a variable that don't exist, javascript throw an exception but when I try to access a property that don't exist in an object, javascript returns an undefined object? For example, this case returns an undefined object: function Foo(){ console.log(this.bar); } Foo(); But, in this other example, javascript throw an exception: function Foo(){ console.log(bar); } Foo(); ReferenceError: bar is not defined

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  • One big call vs. multiple smaller TSQL calls

    - by BrokeMyLegBiking
    I have a ADO.NET/TSQL performance question. We have two options in our application: 1) One big database call with multiple result sets, then in code step through each result set and populate my objects. This results in one round trip to the database. 2) Multiple small database calls. There is much more code reuse with Option 2 which is an advantage of that option. But I would like to get some input on what the performance cost is. Are two small round trips twice as slow as one big round trip to the database, or is it just a small, say 10% performance loss? We are using C# 3.5 and Sql Server 2008 with stored procedures and ADO.NET.

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  • GPA and Resume and PDF vs Doc.

    - by Recursion
    As a recent graduate of a CS program, I am looking for my first job. My GPA was not above 3.0, but incredibly close. Should I still put my GPA on my resume, or is it best to leave it out? Also, is it best to submit a resume as a PDF or a DOC file?

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  • Huge page buffer vs. multiple simultaneous processes

    - by Andrei K.
    One of our customer has a 35 Gb database with average active connections count about 70-80. Some tables in database have more than 10M records per table. Now they have bought new server: 4 * 6 Core = 24 Cores CPU, 48 Gb RAM, 2 RAID controllers 256 Mb cache, with 8 SAS 15K HDD on each. 64bit OS. I'm wondering, what would be a fastest configuration: 1) FB 2.5 SuperServer with huge buffer 8192 * 3500000 pages = 29 Gb or 2) FB 2.5 Classic with small buffer of 1000 pages. Maybe some one has tested such case before and will save me days of work :) Thanks in advance.

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  • What are the pros and cons of using manual list iteration vs recursion through fail

    - by magus
    I come up against this all the time, and I'm never sure which way to attack it. Below are two methods for processing some season facts. What I'm trying to work out is whether to use method 1 or 2, and what are the pros and cons of each, especially large amounts of facts. methodone seems wasteful since the facts are available, why bother building a list of them (especially a large list). This must have memory implications too if the list is large enough ? And it doesn't take advantage of Prolog's natural backtracking feature. methodtwo takes advantage of backtracking to do the recursion for me, and I would guess would be much more memory efficient, but is it good programming practice generally to do this? It's arguably uglier to follow, and might there be any other side effects? One problem I can see is that each time fail is called, we lose the ability to pass anything back to the calling predicate, eg. if it was methodtwo(SeasonResults), since we continually fail the predicate on purpose. So methodtwo would need to assert facts to store state. Presumably(?) method 2 would be faster as it has no (large) list processing to do? I could imagine that if I had a list, then methodone would be the way to go.. or is that always true? Might it make sense in any conditions to assert the list to facts using methodone then process them using method two? Complete madness? But then again, I read that asserting facts is a very 'expensive' business, so list handling might be the way to go, even for large lists? Any thoughts? Or is it sometimes better to use one and not the other, depending on (what) situation? eg. for memory optimisation, use method 2, including asserting facts and, for speed use method 1? season(spring). season(summer). season(autumn). season(winter). % Season handling showseason(Season) :- atom_length(Season, LenSeason), write('Season Length is '), write(LenSeason), nl. % ------------------------------------------------------------- % Method 1 - Findall facts/iterate through the list and process each %-------------------------------------------------------------- % Iterate manually through a season list lenseason([]). lenseason([Season|MoreSeasons]) :- showseason(Season), lenseason(MoreSeasons). % Findall to build a list then iterate until all done methodone :- findall(Season, season(Season), AllSeasons), lenseason(AllSeasons), write('Done'). % ------------------------------------------------------------- % Method 2 - Use fail to force recursion %-------------------------------------------------------------- methodtwo :- % Get one season and show it season(Season), showseason(Season), % Force prolog to backtrack to find another season fail. % No more seasons, we have finished methodtwo :- write('Done').

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