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  • RestKit : Not able to perform mapping using coredata

    - by Ashish Beuwria
    I'm using rest kit 0.20.3 and Xcode 5. Without core data I'm able to perform all rest kit operation, but when I've tried it with core data, I'm not even able to perform GET due to some problem. I can't figure it out. I'm new with core data. So pls help. Here is my code: AppDelegate.m @implementation CardGameAppDelegate @synthesize managedObjectContext = _managedObjectContext; @synthesize managedObjectModel = _managedObjectModel; @synthesize persistentStoreCoordinator = _persistentStoreCoordinator; - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { RKLogConfigureByName("RestKit", RKLogLevelWarning); RKLogConfigureByName("RestKit/ObjectMapping", RKLogLevelTrace); RKLogConfigureByName("RestKit/Network", RKLogLevelTrace); RKObjectManager *objectManager = [RKObjectManager managerWithBaseURL:[NSURL URLWithString:@"http://192.168.1.3:3010/"]]; RKManagedObjectStore *objectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:self.managedObjectModel]; objectManager.managedObjectStore = objectStore; RKEntityMapping *playerMapping = [RKEntityMapping mappingForEntityForName:@"Player" inManagedObjectStore:objectStore]; [playerMapping addAttributeMappingsFromDictionary:@{@"id": @"playerId", @"name": @"playerName", @"age" : @"playerAge", @"created_at": @"createdAt", @"updated_at": @"updatedAt"}]; RKResponseDescriptor *responseDesc = [RKResponseDescriptor responseDescriptorWithMapping:playerMapping method:RKRequestMethodGET pathPattern:@"/players.json" keyPath:nil statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)]; [objectManager addResponseDescriptor:responseDesc]; PlayersTableViewController *ptvc = (PlayersTableViewController *)self.window.rootViewController; ptvc.managedObjectContext = self.managedObjectContext; return YES; } and code for playerTableViewController.h #import <UIKit/UIKit.h> @interface PlayersTableViewController : UITableViewController <NSFetchedResultsControllerDelegate> @property (strong, nonatomic) NSFetchedResultsController *fetchedResultsController; @property (strong, nonatomic) NSManagedObjectContext *managedObjectContext; @end and PlayerTableViewController.m get method: -(void)loadPlayers{ [[RKObjectManager sharedManager] getObjectsAtPath:@"/players.json" parameters:nil success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult){ [self.refreshControl endRefreshing]; } failure:^(RKObjectRequestOperation *operation, NSError *error) { [self.refreshControl endRefreshing]; UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"An Error Has Occurred" message:[error localizedDescription] delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil]; [alertView show]; }]; } I'm getting the following error : Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Unable to perform mapping: No `managedObjectContext` assigned. (Mapping response.URL = http://192.168.1.3:3010/players.json)'

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  • large amount of data in many text files - how to process?

    - by Stephen
    Hi, I have large amounts of data (a few terabytes) and accumulating... They are contained in many tab-delimited flat text files (each about 30MB). Most of the task involves reading the data and aggregating (summing/averaging + additional transformations) over observations/rows based on a series of predicate statements, and then saving the output as text, HDF5, or SQLite files, etc. I normally use R for such tasks but I fear this may be a bit large. Some candidate solutions are to 1) write the whole thing in C (or Fortran) 2) import the files (tables) into a relational database directly and then pull off chunks in R or Python (some of the transformations are not amenable for pure SQL solutions) 3) write the whole thing in Python Would (3) be a bad idea? I know you can wrap C routines in Python but in this case since there isn't anything computationally prohibitive (e.g., optimization routines that require many iterative calculations), I think I/O may be as much of a bottleneck as the computation itself. Do you have any recommendations on further considerations or suggestions? Thanks

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  • in free(): error: junk pointer, too high to make sense Segmentation fault: 11 (core dumped) gprof

    - by Mayank
    I am trying to profile my application. For this I compiled my code with -pg and -lc_p option, it compiled successfully During run time I am getting the following error. in free(): error: junk pointer, too high to make sense Segmentation fault: 11 (core dumped) Doing GDB gives error as. (gdb) b main Breakpoint 1 at 0x5124d4: (gdb) r warning: Unable to get location for thread creation breakpoint: generic error [New LWP 100085] cacheIp in free(): error: junk pointer, too high to make sense Program received signal SIGSEGV, Segmentation fault. [Switching to LWP 100085] 0x00000000006c3a1f in pthread_sigmask () My application is multi threaded and is a combination of C and C++ code. uname -a FreeBSD 6.3-RELEASE FreeBSD 6.3-RELEASE #0: Wed Jan 16 01:43:02 UTC 2008 [email protected]:/usr/obj/usr/src/sys/SMP amd64 Why is the code crashing. Am I missing something.

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  • [java] Efficiency of while(true) ServerSocket Listen

    - by Submerged
    I am wondering if a typical while(true) ServerSocket listen loop takes an entire core to wait and accept a client connection (Even when implementing runnable and using Thread .start()) I am implementing a type of distributed computing cluster and each computer needs every core it has for computation. A Master node needs to communicate with these computers (invoking static methods that modify the algorithm's functioning). The reason I need to use sockets is due to the cross platform / cross language capabilities. In some cases, PHP will be invoking these java static methods. I used a java profiler (YourKit) and I can see my running ServerSocket listen thread and it never sleeps and it's always running. Is there a better approach to do what I want? Or, will the performance hit be negligible? Please, feel free to offer any suggestion if you can think of a better way (I've tried RMI, but it isn't supported cross-language. Thanks everyone

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  • Implementing full text search on iPhone?

    - by Nimrod
    I'm looking for suggestions on the best way to implement a full-text search on some static data on the iPhone. Basically I have an app that contains the offline version of a web site, about 50MB of text, and I'd like for users to be able to search for terms. I figure that I should somehow build an table of ("word", reference_to_file_containing_word) or something, put that into either Core Data or just sqlite, index the "word" column, then have the search facility search the table for search terms and take the intersection of the sets of results for the terms or something. That wouldn't allow people to search for phrases but it would be pretty easy and probably not too slow. I'd like to just use existing SDK features for this. Should I use Core Data or sqlite? Does anyone have any other ideas on how this could be done?

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  • How can I sort an NSTableColumn of NSStrings ignoring "The " and "A "?

    - by David Barry
    I've got a simple Core Data application that I'm working on to display my movie collection. I'm using an NSTableView, with it's columns bound to attributes of my Core Data store through an NSArrayController object. At this point the columns sort fine(for numeric values) when the column headers are clicked on. The issue I'm having is with the String sorting, they sort, however it's done in standard string fashion, with Uppercase letters preceding lowercase(i.e. Z before a). In addition to getting the case sorting to work properly, I would like to be able to ignore a prefix of "The " or "A " when sorting the strings. What is the best way to go about this in Objective-C/Cocoa?

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  • iPhone OS: KVO: Why is my Observer only getting notified at applicationDidfinishLaunching

    - by nickthedude
    I am basically trying to implement an achievement tracking setup in my app. I have a managedObjectModel class called StatTracker to keep track of all sorts of stats and I want my Achievement tracking class to be notified when those stats change so I can check them against a value and see if the user has earned an achievement. I've tried to impliment KVO and I think I'm pretty close to making it happen but the problem I'm running into is this: So in the appDelegate i have an Ivar for my Achievement tracker class, I attach it as an observer to a property value of my statTracker core data entity in the applicationDidFinishLaunching method. I know its making the connection because I've been able to trigger a UIAlert in my AchievementTracker instance, and I've put several log statements that should be triggered whenever the value on the StatTracker's property changes. the log statement appears only once at the application launch. I'm wondering if I'm missing something in the whole object lifecycle scheme of things, I just don't understand why the observer stops getting notified of changes after the applicationDidFinishLaunching method has run. Does it have something to do with the scope of the AchievementTracker reference or more likely the reference to my core data StatTracker is going away once that method finishes up. I guess I'm not sure the right place to place these if that is the case. Would love some help. Here is the code where I add the observer in my appDidFinishLaunching method: [[CoreDataSingleton sharedCoreDataSingleton] incrementStatTrackerStat:@"timesLaunched"]; achievementsObserver = [[AchievementTracker alloc] init]; StatTracker *object = nil; object = [[[CoreDataSingleton sharedCoreDataSingleton] getStatTracker] objectAtIndex:0]; NSLog(@"%@",[object description]); [[CoreDataSingleton sharedCoreDataSingleton] addObserver:achievementsObserver toStat:@"refreshCount"]; here is the code in my core data singleton: -(void) addObserver:(id)observer toStat:(NSString *) statToObserve { NSLog(@"observer added"); NSArray *array = [[NSArray alloc] init]; array = [self getStatTracker]; [[array objectAtIndex:0] addObserver:observer forKeyPath:statToObserve options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld context:NULL]; } and my AchievementTracker: - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context { NSLog(@"achievemnt hit"); //NSLog("%@", [change description]); if ([keyPath isEqual:@"refreshCount"] && ((NSInteger)[change valueForKey:@"NSKeyValueObservingOptionOld"] == 60) ) { NSLog(@"achievemnt hit inside"); UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"title" message:@"achievement unlocked" delegate:self cancelButtonTitle:@"cancel" otherButtonTitles:nil]; [alert show]; } }

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  • Is there an existing solution to the multithreaded data structure problem?

    - by thr
    I've had the need for a multi-threaded data structure that supports these claims: Allows multiple concurrent readers and writers Is sorted Is easy to reason about Fulfilling multiple readers and one writer is a lot easier, but I really would wan't to allow multiple writers. I've been doing research into this area, and I'm aware of ConcurrentSkipList (by Lea based on work by Fraser and Harris) as it's implemented in Java SE 6. I've also implemented my own version of a concurrent Skip List based on A Provably Correct Scalable Concurrent Skip List by Herlihy, Lev, Luchangco and Shavit. These two implementations are developed by people that are light years smarter then me, but I still (somewhat ashamed, because it is amazing work) have to ask the question if these are the two only viable implementations of a concurrent multi reader/writer data structures available today?

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  • XCode - Copy sqlite DB from simulator and copy onto device for testing

    - by Neal L
    Hello, I am working on a Core Data app, and have populated the sqlite file in the iPhone Simulator with all of the fixtures/data that I use to test the app. I would like to use that sqlite file as a standardized set of testing data. The devices that I test the app on all have different data sets, and I would like to standardize on the one in the simulator. Is there a way in XCode (3 or 4) to add a step to the build/install process that will copy the sqlite file from the iPhone Simulator and install it over the file on the phone (if one exists)? Thanks, Neal

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  • Proper binding data to combobox and handling its events.

    - by Wodzu
    Hi guys. I have a table in SQL Server which looks like this: ID Code Name Surname 1 MS Mike Smith 2 JD John Doe 3 UP Unknown Person and so on... Now I want to bind the data from this table into the ComboBox in a way that in the ComboBox I have displayed value from the Code column. I am doing the binding in this way: SqlDataAdapter sqlAdapter = new SqlDataAdapter("SELECT * FROM dbo.Users ORDER BY Code", MainConnection); sqlAdapter.Fill(dsUsers, "Users"); cbxUsers.DataSource = dsUsers.Tables["Users"]; cmUsers = (CurrencyManager)cbxUsers.BindingContext[dsUsers.Tables["Users"]]; cbxUsers.DisplayMember = "Code"; And this code seems to work. I can scroll through the list of Codes. Also I can start to write code by hand and ComboBox will autocomplete the code for me. However, I wanted to put a label at the top of the combobox to display Name and Surname of the currently selected user code. My line of though was like that: "So, I need to find an event which will fire up after the change of code in combobox and in that event I will get the current DataRow..." I was browsing through the events of combobox, tried many of them but without a success. For example: private void cbxUsers_SelectionChangeCommitted(object sender, EventArgs e) { if (cmUsers != null) { DataRowView drvCurrentRowView = (DataRowView)cmUsers.Current; DataRow drCurrentRow = drvCurrentRowView.Row; lblNameSurname.Text = Convert.ToString(drCurrentRow["Name"]) + " " + Convert.ToString(drCurrentRow["Surname"]); } } This give me a strange results. Firstly when I scroll via mouse scroll it doesn't return me the row wich I am expecting to obtain. For example on JD it shows me "Mike Smith", on MS it shows me "John Doe" and on UP it shows me "Mike Smith" again! The other problem is that when I start to type in ComboBox and press enter it doesn't trigger the event. However, everything works as expected when I bind data to lblNameSurname.Text in this way: lblNameSurname.DataBindings.Add("Text", dsusers.Tables["Users"], "Name"); The problem here is that I can bind only one column and I want to have two. I don't want to use two labels for it (one to display name and other to display surname). So, what is the solution to my problem? Also, I have one question related to the data selection in ComboBox. Now, when I type something in the combobox it allows me to type letters that are not existing in the list. For example, I start to type "J" and instead of finishing with "D" so I would have "JD", I type "Jsomerandomtexthere". Combobox will allow that but such item does not exists on the list. In other words, I want combobox to prevent user from typing code which is not on the list of codes. Thanks in advance for your time.

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  • Efficiency of while(true) ServerSocket Listen

    - by Submerged
    I am wondering if a typical while(true) ServerSocket listen loop takes an entire core to wait and accept a client connection (Even when implementing runnable and using Thread .start()) I am implementing a type of distributed computing cluster and each computer needs every core it has for computation. A Master node needs to communicate with these computers (invoking static methods that modify the algorithm's functioning). The reason I need to use sockets is due to the cross platform / cross language capabilities. In some cases, PHP will be invoking these java static methods. I used a java profiler (YourKit) and I can see my running ServerSocket listen thread and it never sleeps and it's always running. Is there a better approach to do what I want? Or, will the performance hit be negligible? Please, feel free to offer any suggestion if you can think of a better way (I've tried RMI, but it isn't supported cross-language. Thanks everyone

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  • Where would you document standardized complex data that is passed between many objects and methods?

    - by Eli
    Hi All, I often find myself with fairly complex data that represents something that my objects will be working on. For example, in a task-list app, several objects might work with an array of tasks, each of which has attributes, temporal expressions, sub tasks and sub sub tasks, etc. One object will collect data from web forms, standardize it into a format consumable by the class that will save them to the database, another object will pull them from the database, put them in the standard format and pass them to the display object, or the update object, etc. The data itself can become a fairly complex series of arrays and sub arrays, representing a 'task' or list of tasks. For example, the below might be one entry in a task list, in the format that is consumable by the various objects that will work on it. Normally, I just document this in a file somewhere with an example. However, I am thinking about the best way to add it to something like PHPDoc, or another standard doc system. Where would you document your consumable data formats that are for many or all of the objects / methods in your app? Array ( [Meta] => Array ( //etc. ) [Sched] => Array ( [SchedID] => 32 [OwnerID] => 2 [StatusID] => 1 [DateFirstTask] => 2011-02-28 [DateLastTask] => [MarginMonths] => 3 ) [TemporalExpressions] => Array ( [0] => Array ( [type] => dw [TemporalExpID] => 3 [ord] => 2 [day] => 6 [month] => 4 ) [1] => Array ( [type] => dm [TemporalExpID] => 32 [day] => 28 [month] => 2 ) ) [Task] => Array ( [SchedTaskID] => 32 [SchedID] => 32 [OwnerID] => 2 [UserID] => 5 [ClientID] => 9 [Title] => Close Prior Year [Body] => [DueTime] => ) [SubTasks] => Array ( [101] => Array ( [SchedSubTaskID] => 101 [ParentST] => [RootT] => 32 [UserID] => 2 [Title] => Review Profit and Loss by Class [Body] => [DueDiff] => 0 ) [102] => Array ( [SchedSubTaskID] => 102 [ParentST] => [RootT] => 32 [UserID] => 2 [Title] => Review Balance Sheet [Body] => [DueDiff] => 0 ) [103] => Array ( [SchedSubTaskID] => 103 [ParentST] => [RootT] => 32 [UserID] => 2 [Title] => Review Current Year for Prior Year Expenses to Accrue [Body] => Look at Journal Entries that are templates as well. [DueDiff] => 0 ) [104] => Array ( [SchedSubTaskID] => 104 [ParentST] => [RootT] => 32 [UserID] => 2 [Title] => Review Prior Year Membership from 11/1 - 12/31 to Accrue to Current Year [Body] => [DueDiff] => 0 ) [105] => Array ( [SchedSubTaskID] => 105 [ParentST] => [RootT] => 32 [UserID] => 2 [Title] => Enter Vacation Accrual [Body] => [DueDiff] => 0 ) [106] => Array ( [SchedSubTaskID] => 106 [ParentST] => 105 [RootT] => 32 [UserID] => 2 [Title] => Email Peter requesting Vacation Status of Employees at Year End [Body] => We need Employee Name, Rate and Days of Vacation left to use. We also need to know if the employee used any of the prior year's vacation. [DueDiff] => 43 ) [107] => Array ( [SchedSubTaskID] => 107 [ParentST] => [RootT] => 32 [UserID] => 2 [Title] => Grants Receivable at Year End [Body] => [DueDiff] => 0 ) [108] => Array ( [SchedSubTaskID] => 108 [ParentST] => 107 [RootT] => 32 [UserID] => 2 [Title] => Email Peter Requesting if there were and Grants Receivable at year end [Body] => [DueDiff] => 43 ) ) )

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  • How to manipulate data in View using Asp.Net Mvc RC 2?

    - by Picflight
    I have a table [Users] with the following columns: INT SmallDateTime Bit Bit [UserId], [BirthDate], [Gender], [Active] Gender and Active are Bit that hold either 0 or 1. I am displaying this data in a table on my View. For the Gender I want to display 'Male' or 'Female', how and where do I manipulate the 1's and 0's? Is it done in the repository where I fetch the data or in the View? For the Active column I want to show a checkBox that will AutoPostBack on selection change and update the Active filed in the Database. How is this done without Ajax or jQuery?

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  • Testing file existence using NSURL

    - by Peter Hosey
    Snow Leopard introduced many new methods to use NSURL objects to refer to files, not pathnames or Core Services' FSRefs. However, there's one task I can't find a URL-based method for: Testing whether a file exists. I'm looking for a URL-based version of -[NSFileManager fileExistsAtPath:]. Like that method, it should return YES if the URL describes anything, whether it's a regular file, a directory, or anything else. I could attempt to look up various resource values, but none of them are explicitly guaranteed to not exist if the file doesn't, and some of them (e.g., NSURLEffectiveIconKey) could be costly if it does. I could just use NSFileManager's fileExistsAtPath:, but if there's a more modern method, I'd prefer to use that. Is there a simple method or function in Cocoa, CF, or Core Services that's guaranteed/documented to tell me whether a given file (or file-reference) URL refers to a file-system object that exists?

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  • How is 'processing credit card data' defined (PCI)?

    - by Chris
    If i have a web application and i receive credit card data transmitted via a POST request by a web browser over HTTPS and instantly open a socket (SSL) to a remote PCI compilant card processor to forward the data and wait for a response, am i allowed to do that? or is this receiving the data with my application and forwarding it already subject of "processing credit card data"? if i create an iframe that is displayed in a client browser to enter cc data and this iframe posts the data via HTTPS to remote card processor (directly!) is this already a case of processing credit card data? even if my application code 'doesnt touch' the entered data with any event handlers? i'm interested in the definition "credit card data processing". when does it start to be a cc data processing application? can somebody maybe point me to that section in PCI-DSS standard that clearly defines when you start to 'be a processing application'? Thanks,

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  • transforming binary data using ssis and sql server 2008

    - by Rick
    Hello All - I have a task to import/transform and extract zipped binary files that contain both text data as well as embeded binary data. Within the data is data that is relational in nature and needs to be processed into a defined database structure. Currently I have a C# single threaded app that essentially grabs all the files from the directory (currently there is 13K files of varying sizes) and extracts the data on a single thread line by line inserts to the database. As you could imagine this is a very slow process and unacceptable. There are several different parsing routines used depending on the header record in the file. There are potentially upto a million rows per file when all the data is extracted to the row level of detail. Follow on task is to parse those rows into their appropriate tables based on is content. i.e. the textual content has to be parsed further into "buckets" of like data in the database. That about sums up the big picture. Now for the problem task list. How do i iterate through a packet of data using SSIS? In the app the file is decompressed and then is parsed using streams data type and byte arrays and is routed to the required parsing routine based on the header data of each packet. There is bit swapping involved as well. Should i wrap up the app code into a script task(s) and let it do the custom processing? The data is seperated by year and the sql server tables is partitioned by year as well. I need to be able to "catch" bad file data as well and process by hand most likely. Should i simply load the zipped file to sql as a blob and parse the file with T-SQL? Would that be multi threaded if done that way? Not sure how to do the parsing in tsql that is involved here. Which do you think would be faster? Potentially the data that is currently processed via files could come to us via a socket. Can SSIS collect that data in real time? How would i go about setting that up? Processing these new files from the directorys will become a daily task. I can manage the data once i get it to sql server. Getting it there in a timely fashion seems to be the long pole in the tent for me. I would appreciate any comments or suggestions from the group. Rick

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  • Moving Git Projects between computers

    - by 01
    I have a project that i use at two places(i dont use git server). When i copy the project at second place i have to check-in all the files(but they have not changed), git shows me for example @@ -1,8 +1,8 @@ -#Sat Mar 06 19:39:27 CET 2010 -eclipse.preferences.version=1 -org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled -org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.6 -org.eclipse.jdt.core.compiler.compliance=1.6 -org.eclipse.jdt.core.compiler.problem.assertIdentifier=error -org.eclipse.jdt.core.compiler.problem.enumIdentifier=error -org.eclipse.jdt.core.compiler.source=1.6 +#Sat Mar 06 19:39:27 CET 2010 +eclipse.preferences.version=1 +org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled +org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.6 +org.eclipse.jdt.core.compiler.compliance=1.6 +org.eclipse.jdt.core.compiler.problem.assertIdentifier=error +org.eclipse.jdt.core.compiler.problem.enumIdentifier=error +org.eclipse.jdt.core.compiler.source=1.6 i did at both places the command git config --global core.autocrlf false but it doesnt help with this problem

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  • remove duplicates from object array data java

    - by zahir hussain
    hi i want to know how to remove duplicates in object. for example cat c[] = new cat[10]; c[1].data = "ji"; c[2].data = "pi"; c[3].data = "ji"; c[4].data = "lp"; c[5].data = "ji"; c[6].data = "pi"; c[7].data = "jis"; c[8].data = "lp"; c[9].data = "js"; c[10].data = "psi"; i would like to remove the duplicates value from object array. thanks and advance

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  • Processes sharing cores on Ubuntu system

    - by muckabout
    My coworkers and I share an 8-core server running Ubuntu for our batch processes. I tend to run 4 processes at a time, each of which consumes 100% CPU per core when nothing else is running. When a coworker runs his processes (typically about 4 at a time), his also get 100% per. However, when both of us run ours (he always goes first), his still get 100% and mine seem to divide the remaining processing power and linger in the 10-40% range. I even reniced his process to a lower value and it did not change. What are the issues that may cause this?

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  • What are the Options for Storing Hierarchical Data in a Relational Database?

    - by orangepips
    Good Overviews One more Nested Intervals vs. Adjacency List comparison: the best comparison of Adjacency List, Materialized Path, Nested Set and Nested Interval I've found. Models for hierarchical data: slides with good explanations of tradeoffs and example usage Representing hierarchies in MySQL: very good overview of Nested Set in particular Hierarchical data in RDBMSs: most comprehensive and well organized set of links I've seen, but not much in the way on explanation Options Ones I am aware of and general features: Adjacency List: Columns: ID, ParentID Easy to implement. Cheap node moves, inserts, and deletes. Expensive to find level (can store as a computed column), ancestry & descendants (Bridge Hierarchy combined with level column can solve), path (Lineage Column can solve). Use Common Table Expressions in those databases that support them to traverse. Nested Set (a.k.a Modified Preorder Tree Traversal) First described by Joe Celko - covered in depth in his book Trees and Hierarchies in SQL for Smarties Columns: Left, Right Cheap level, ancestry, descendants Compared to Adjacency List, moves, inserts, deletes more expensive. Requires a specific sort order (e.g. created). So sorting all descendants in a different order requires additional work. Nested Intervals Combination of Nested Sets and Materialized Path where left/right columns are floating point decimals instead of integers and encode the path information. Bridge Table (a.k.a. Closure Table: some good ideas about how to use triggers for maintaining this approach) Columns: ancestor, descendant Stands apart from table it describes. Can include some nodes in more than one hierarchy. Cheap ancestry and descendants (albeit not in what order) For complete knowledge of a hierarchy needs to be combined with another option. Flat Table A modification of the Adjacency List that adds a Level and Rank (e.g. ordering) column to each record. Expensive move and delete Cheap ancestry and descendants Good Use: threaded discussion - forums / blog comments Lineage Column (a.k.a. Materialized Path, Path Enumeration) Column: lineage (e.g. /parent/child/grandchild/etc...) Limit to how deep the hierarchy can be. Descendants cheap (e.g. LEFT(lineage, #) = '/enumerated/path') Ancestry tricky (database specific queries) Database Specific Notes MySQL Use session variables for Adjacency List Oracle Use CONNECT BY to traverse Adjacency Lists PostgreSQL ltree datatype for Materialized Path SQL Server General summary 2008 offers HierarchyId data type appears to help with Lineage Column approach and expand the depth that can be represented.

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  • SharpArch.Core.PreconditionException: For better clarity and reliability, Entities with an assigned

    - by Quintin Par
    When I do a save of an entity with assigned id I get a SharpArch.Core.PreconditionException: For better clarity and reliability, Entities with an assigned Id must call Save or Update My class is public class CompanyUserRepository : RepositoryWithTypedId<CompanyUser, string>, ICompanyUserRepository { public override CompanyUser SaveOrUpdate(CompanyUser entity) { var user = base.SaveOrUpdate(entity); //Do some stuff return user; } } How do I go about saving this entity? RepositoryWithTypedId does not expose a Save method Related question. This tells you the reason, but I haven't found out the Sharp Architecture way to do a Save.

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  • Does correcting a value in an validation method mark the object as dirty?

    - by dontWatchMyProfile
    From the docs: If you change the input value in a validate:error: method, you must ensure that you only change the value if it is invalid or uncoerced. The reason is that, since the object and context are now dirtied, Core Data may validate that key again later. If you keep performing a coercion in a validation method, this can therefore produce an infinite loop. So when I modify a value in a validation method, the context gets dirtied? And the next time I save, the validation happens again - and when I change the value even if the validation is OK, then the context is again dirtied, and revalidated again - and I change the value, and Core Data validates, again, because the context is dirtied. And so on...for ever... is that right? Or did they try to say something different?

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  • My multithread program works slowly or appear deadlock on dual core machine, please help

    - by Shangping Guo
    I have a program with several threads, one thread will change a global when it exits itself and the other thread will repeatedly poll the global. No any protection on the globals. The program works fine on uni-processor. On dual core machine, it works for a while and then halt either on Sleep(0) or SuspendThread(). Would anyone be able to help me out on this? The code would be like this: Thread 1: do something... while(1) { ..... flag_thread1_running=false; SuspendThread(GetCurrentThread()); continue; } Thread 2 .... while(flag_thread1_running==false) Sleep(0); ....

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  • List of fundamental data structures - what am I missing?

    - by jboxer
    I've been studying my fundamental data structures a bunch recently, trying to make sure I've got them down cold. By "fundamental", I mean the real basic ones. Fancy ones like Red-Black Trees and Bloom Filters are clearly worth knowing, but they're usually either enhancements of fundamental ones (Red-Black Trees are binary search trees with special properties to keep them balanced) or they're only useful in very specific situations (Bloom Filters). So far, I'm "fluent" in the following data structures: Arrays Linked Lists Stacks/Queues Binary Search Trees Heaps/Priority Queues Hash Tables However, I feel like I'm missing something. Are there any fundamental ones that I'm forgetting about? EDIT: Added these after posting the question Strings (suggested by catchmeifyoutry) Sets (suggested by Peter) Graphs (suggested by Nick D and aJ) B-Trees (Suggested by tloach) I'm a little on-the-fence about whether these are too fancy or not, but I think they're different enough from the fundamental structures (and important enough) to be worth studying as fundamental.

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