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  • Tree-like queues

    - by Rehno Lindeque
    I'm implementing a interpreter-like project for which I need a strange little scheduling queue. Since I'd like to try and avoid wheel-reinvention I was hoping someone could give me references to a similar structure or existing work. I know I can simply instantiate multiple queues as I go along, I'm just looking for some perspective by other people who might have better ideas than me ;) I envision that it might work something like this: The structure is a tree with a single root. You get a kind of "insert_iterator" to the root and then push elements onto it (e.g. a and b in the example below). However, at any point you can also split the iterator into multiple iterators, effectively creating branches. The branches cannot merge into a single queue again, but you can start popping elements from the front of the queue (again, using a kind of "visitor_iterator") until empty branches can be discarded (at your discretion). x -> y -> z a -> b -> { g -> h -> i -> j } f -> b Any ideas? Seems like a relatively simple structure to implement myself using a pool of circular buffers but I'm following the "think first, code later" strategy :) Thanks

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  • CoreData is saving model without the save: method being called

    - by chris
    I have a list of items with a plus button in the navigation bar that opens up a modal window containing a table of the models attributes, that displays a form when the table items are clicked (pretty standard form style). For some reason if I click the plus button to open the form to create a new model, then immediately click the done button, the person model is saved. The action linked to the done button does nothing but call on a delegate method notifying the personListViewController to close the window. The apple docs do state that the model is not saved after calling the insertNewObjectForEntityName: ... Simply creating a managed object does not cause it to be saved to a persistent store. The managed object context acts as a scratchpad. I am at a lost to why this is happening, but every time I click the done button I have a new blank item in the original tableView. I am using SDK v3.1.3 // PersonListViewController - open modal window - (void)addPerson { // Load the new form PersonNewViewController *newController = [[PersonNewViewController alloc] init]; newController.modalFormDelegate = self; [self presentModalViewController:newController animated:YES]; [newController release]; } // PersonFormViewController - (void)viewDidLoad { [super viewDidLoad]; if ( person == nil ) { MyAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate]; self.person = [NSEntityDescription insertNewObjectForEntityForName:@"Person" inManagedObjectContext:appDelegate.managedObjectContext]; } ... UIBarButtonItem *doneButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(done)]; self.navigationItem.rightBarButtonItem = doneButton; [doneButton release]; } - (IBAction) done { [self.modalFormDelegate didCancel]; } // delegate method in the original listViewController - (void) didCancel { [self dismissModalViewControllerAnimated:YES]; }

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  • Building a NSPredicate for a filter

    - by John
    Hi, Just wondering what the best way to build a NSPredicate is if some filters are optional? This is basically for a filter, so if some options aren't selected I don't to filter by them eg. If I have option1 and option2 set for the filter. NSPredicate* predicate = [NSPredicate predicateWithFormat:@"option1 = %@ AND option2 = %@] .... otherwise if just option1 NSPredicate* predicate = [NSPredicate predicateWithFormat:@"option1 = %@] .... The key being there are 10 different options to filter, so I don't want to have to code for the 10x10 possible combinations. Thanks

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  • Mysql: create index on 1.4 billion records

    - by SiLent SoNG
    I have a table with 1.4 billion records. The table structure is as follows: CREATE TABLE text_page ( text VARCHAR(255), page_id INT UNSIGNED ) ENGINE=MYISAM DEFAULT CHARSET=ascii The requirement is to create an index over the column text. The table size is about 34G. I have tried to create the index by the following statement: ALTER TABLE text_page ADD KEY ix_text (text) After 10 hours' waiting I finally give up this approach. Is there any workable solution on this problem? UPDATE: the table is unlikely to be updated or inserted or deleted. The reason why to create index on the column text is because this kind of sql query would be frequently executed: SELECT page_id FROM text_page WHERE text = ?

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  • MS SQL Cursor data as result of stored procedure

    - by Dmitry Borovsky
    Hello, I have some stored procedure DECLARE cursor FOR SELECT [FooData] From [FooTable]; OPEN cursor ; FETCH NEXT FROM cursor INTO @CurrFooData; WHILE @@FETCH_STATUS = 0 BEGIN SELECT @CurrFooData AS FooData; INSERT INTO Bar (BarData) VALUES(@CurrFooData); FETCH NEXT FROM cursor INTO @CurrFooData; END; CLOSE OldestFeeds DEALLOCATE OldestFeeds But in result I have a lot of tables, not one. How can I return one table with 'FooData' column and all '@CurrFooData' rows?

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  • Tag Cloud Data Backend

    - by Waldron
    I want to be able to generate tag clouds from free text that comes from any number of different sources. For clarity, I'm not talking about how to display a tag cloud once the critical tags/phrases are already discovered, I'm hoping to be able to discover the meaningful phrases themselves... preferable on a PHP/MySQL stack. If I had to do this myself, I'd start by establishing some kind of index for words/phrases that gives a "normal" frequency for any word/phrase. eg "Constantinople" occurs once in every 1,000,000 words on average (normal frequency "0.000001"). Then as I analyze a body of text, I'd find the individual words/phrases (another challenge!), find frequencies of each within the input, and measure against the expected freqeuncy. Words that have the highest ratio against expected frequency get boosted priority in the cloud. I'd like to believe someone else has already done this, WAY better than I could hope to, but I'll be damned if I can find it. Any recommendations??

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  • converting date data type into varchar

    - by Sheetal Inani
    I have some dates fields in table. These columns contain dates in the following format: mmddyy For example: 31/12/2010 00:00:00:0000 I need to import these values into a table which is set to varchar and numeric and formats dates like this: monthName varchar Year numeric(4,0) currently I'm using INSERT INTO [School].[dbo].[TeacherAttendenceDet] ([TeacherCode], [MonthName], [Year]) (SELECT MAX(employeecode), Datename(MONTH, dateofjoining) AS MONTH, Datepart(YEAR, dateofjoining) AS DATE FROM employeedet GROUP BY dateofjoining) but datename() gives result in date format.. I have to save it in varchar format How can I do this? this is employeemast table: EmployeeCode numeric(5, 0) PayScaleCode numeric(7, 0) DesignationCode varchar(50) CityCode numeric(5, 0) EmployeeName varchar(50) FatherName varchar(50) BirthDate varchar(50) DateOfJoining varchar(50) Address varchar(150) this is TeacherAttendenceDet table TeacherCode numeric(5, 0) Unchecked Year numeric(4, 0) Unchecked MonthName varchar(12) Unchecked i have to insert in teacherattendencedet table the monthname and year from employeemast

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  • Basic data alignment question

    - by Broken Logic
    I've been playing around to see how my computer works under the hood. What I'm interested in is seeing is what happens on the stack inside a function. To do this I've written the following toy program: #include <stdio.h> void __cdecl Test1(char a, unsigned long long b, char c) { char c1; unsigned long long b1; char a1; c1 = 'b'; b1 = 4; a1 = 'r'; printf("%d %d - %d - %d %d Total: %d\n", (long)&b1 - (long)&a1, (long)&c1 - (long)&b1, (long)&a - (long)&c1, (long)&b - (long)&a, (long)&c - (long)&b, (long)&c - (long)&a1 ); }; struct TestStruct { char a; unsigned long long b; char c; }; void __cdecl Test2(char a, unsigned long long b, char c) { TestStruct locals; locals.a = 'b'; locals.b = 4; locals.c = 'r'; printf("%d %d - %d - %d %d Total: %d\n", (long)&locals.b - (long)&locals.a, (long)&locals.c - (long)&locals.b, (long)&a - (long)&locals.c, (long)&b - (long)&a, (long)&c - (long)&b, (long)&c - (long)&locals.a ); }; int main() { Test1('f', 0, 'o'); Test2('f', 0, 'o'); return 0; } And this spits out the following: 9 19 - 13 - 4 8 Total: 53 8 8 - 24 - 4 8 Total: 52 The function args are well behaved but as the calling convention is specified, I'd expect this. But the local variables are a bit wonky. My question is, why wouldn't these be the same? The second call seems to produce a more compact and better aligned stack. Looking at the ASM is unenlightening (at least to me), as the variable addresses are still aliased there. So I guess this is really a question about the assembler itself allocates the stack to local variables. I realise that any specific answer is likely to be platform specific. I'm more interested in a general explanation unless this quirk really is platform specific. For the record though, I'm compiling with VS2010 on a 64bit Intel machine.

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  • Best way to model Customer <--> Address

    - by Jen
    Every Customer has a physical address and an optional mailing address. What is your preferred way to model this? Option 1. Customer has foreign key to Address Customer (id, phys_address_id, mail_address_id) Address (id, street, city, etc.) Option 2. Customer has one-to-many relationship to Address, which contains a field to describe the address type Customer (id) Address (id, customer_id, address_type, street, city, etc.) Option 3. Address information is de-normalized and stored in Customer Customer (id, phys_street, phys_city, etc. mail_street, mail_city, etc.) One of my overriding goals is to simplify the object-relational mappings, so I'm leaning towards the first approach. What are your thoughts?

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  • Reading data from text file in C

    - by themake
    I have a text file which contains words separated by space. I want to take each word from the file and store it. So i have opened the file but am unsure how to assign the word to a char. FILE *fp; fp = fopen("file.txt", "r"); //then i want char one = the first word in the file char two = the second word in the file

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  • If attacker has original data, and encrypted data, can they determine the passphrase?

    - by Brad Cupit
    If an attacker has several distinct items (for example: e-mail addresses) and knows the encrypted value of each item, can the attacker more easily determine the secret passphrase used to encrypt those items? Meaning, can they determine the passphrase without resorting to brute force? This question may sound strange, so let me provide a use-case: User signs up to a site with their e-mail address Server sends that e-mail address a confirmation URL (for example: https://my.app.com/confirmEmailAddress/bill%40yahoo.com) Attacker can guess the confirmation URL and therefore can sign up with someone else's e-mail address, and 'confirm' it without ever having to sign in to that person's e-mail account and see the confirmation URL. This is a problem. Instead of sending the e-mail address plain text in the URL, we'll send it encrypted by a secret passphrase. (I know the attacker could still intercept the e-mail sent by the server, since e-mail are plain text, but bear with me here.) If an attacker then signs up with multiple free e-mail accounts and sees multiple URLs, each with the corresponding encrypted e-mail address, could the attacker more easily determine the passphrase used for encryption? Alternative Solution I could instead send a random number or one-way hash of their e-mail address (plus random salt). This eliminates storing the secret passphrase, but it means I need to store that random number/hash in the database. The original approach above does not require this extra table. I'm leaning towards the the one-way hash + extra table solution, but I still would like to know the answer: does having multiple unencrypted e-mail addresses and their encrypted counterparts make it easier to determine the passphrase used?

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  • Can not issue data manipulation statements with executeQuery in java

    - by user225269
    I'm trying to insert records in mysql database using java, What do I place in this code so that I could insert records: String id; String name; String school; String gender; String lang; Scanner inputs = new Scanner(System.in); System.out.println("Input id:"); id=inputs.next(); System.out.println("Input name:"); name=inputs.next(); System.out.println("Input school:"); school= inputs.next(); System.out.println("Input gender:"); gender= inputs.next(); System.out.println("Input lang:"); lang=inputs.next(); Class.forName("com.mysql.jdbc.Driver"); Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/employee_record", "root", "MyPassword"); PreparedStatement statement = con.prepareStatement("insert into employee values('id', 'name', 'school', 'gender', 'lang');"); statement.executeUpdate();

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  • get data from a querystring

    - by regwe
    i have this querystring that shall open up my page. http://www.a1-one.com/[email protected]&stuid=123456 Now when this page loads, on page_load, I want to pick up email and stuid in two different variables. So I can use them to insert into my database (sql server) how can this be done in vb.net

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  • mysql data being inserted twice via php

    - by Jascha
    I can't for the life of me figure out why this function is causing multiple entries into my database table... When I run the function I end up with two records stacked on top of each one second apart here is the function: function generate_signup_token(){ $connection = new DB_Connect(); // <--- my database connection class $ip = mysql_real_escape_string($_SERVER['REMOTE_ADDR']); $sign_up_token = uniqid(mt_rand(), true); $_SESSION['signup_token'] = $sign_up_token; $sign_up_token = mysql_real_escape_string($sign_up_token); $query = "INSERT INTO `token_manager` (`ip_address`, `signup_token`) VALUES ('$ip', '$sign_up_token')"; mysql_query($query); } generate_signup_token();

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  • Django form and User data

    - by Dean
    I have a model that looks like this: class Client(models.Model): name = models.CharField(max_length=100, primary_key=True) user = models.ForeignKey(User) class Contract(models.Model): title = models.CharField(max_length=100, primary_key=True) start_date = models.DateField() end_date = models.DateField() description = models.TextField() client = models.ForeignKey(Client) user = models.ForeignKey(User) How can i configure a django form so that only clients associated with that user show in the field in the form? My initial thought was this in my forms.py: client = forms.ModelChoiceField(queryset=Client.objects.filter(user__username = User.username)) But it didn't work. So how else would I go about it?

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  • Remove objects from different environments

    - by Fred
    I have an R script file that executes a second R script via: source("../scripts/second_file.R") That second file has the following lines: myfiles <- list.files(".",pattern = "*.csv") ... rm(myfiles) When I run the master R file I get: > source("../scripts/second_file.R") Error in file.remove(myfiles) : object 'myfiles' not found and the program aborts. I think this has something to do with the environment. I looked at ?rm() pages but less than illuminating. I figure I have to give it a position argument, but not sure which.

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  • C# Extension Method for String Data Type

    - by Jimbo
    My web application deals with strings that need to be converted to numbers alot - users often put commas, currency symbols etc. in these fields so what I want to do is create a string extension method that cleans the field up and converts it to a decimal. For example: decimal myNumber = "$1,250.85".ToDecimal(); Can anyone help with this? Thanks!

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  • iPhone - Change entity class (NSManagedObject) to make them initializable

    - by ncohen
    Hi everyone, I would like to use my custom NSManagedObject like a normal object (as well as its regular functions). Is it possible to modify the class in order to be able to initialize it like a normal object? [[myManagedObject alloc] init]; Thanks edit: to clarify the question, will it screw everything up if I change the @dynamic with @synthesize in the implementation?

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  • Strange behavior: save video recorded within app?

    - by Josue Espinosa
    I allow the user to record a video within my app, then later play it again. When a user records a video, I save the URL of the video, then play the video later from the saved URL. I save the video both in the Photos app and in my app. If I delete the video within the photos app, it still plays. After about 7 days, the video gets deleted. I think I am saving in my tmp directory, but i'm not sure. Here is what I am doing: -(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info { NSString *mediaType = [info objectForKey: UIImagePickerControllerMediaType]; [self dismissViewControllerAnimated:YES completion:nil]; // Handle a movie capture if (CFStringCompare ((__bridge_retained CFStringRef) mediaType, kUTTypeMovie, 0) == kCFCompareEqualTo) { NSString *moviePath = [NSString stringWithFormat:@"%@",[[info objectForKey:UIImagePickerControllerMediaURL] path]]; NSURL *videoURL = [info objectForKey:UIImagePickerControllerMediaURL]; NSData *videoData = [NSData dataWithContentsOfURL:videoURL]; _justRecordedVideoURL = [NSString stringWithFormat:@"%@",videoURL]; AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate]; _managedObjectContext = [appDelegate managedObjectContext]; Video *video = [NSEntityDescription insertNewObjectForEntityForName:@"Video" inManagedObjectContext:_managedObjectContext]; [video setVideoData:videoData]; [video setVideoURL:[NSString stringWithFormat:@"%@",videoURL]]; NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init]; dateFormatter.dateStyle = NSDateFormatterLongStyle; [dateFormatter setDateStyle:NSDateFormatterLongStyle]; NSDate *date = [dateFormatter dateFromString:[dateFormatter stringFromDate:[NSDate date]]]; NSString *dateAdded = [dateFormatter stringFromDate:date]; [video setDate_recorded:dateAdded]; if(_currentAthlete != nil){ [video setWhosVideo:_currentAthlete]; } NSError *error = nil; if(![_managedObjectContext save:&error]){ //handle dat error } NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; NSString *tempPath = [documentsDirectory stringByAppendingFormat:@"/vid1.mp4"]; BOOL success = [videoData writeToFile:tempPath atomically:NO]; if(success == FALSE){ NSLog(@"Video was not successfully saved."); } if (UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(moviePath)) { UISaveVideoAtPathToSavedPhotosAlbum(moviePath, self, @selector(video:didFinishSavingWithError:contextInfo:), nil); } } } Am I saving it incorrectly? When I go to play the video, it works fine, after a couple days the video will play without audio, then eventually it will be gone. Any ideas why?

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  • how to fetch data from multiple tables MySQL

    - by faisal
    hi all, I am looking some help in php+MySQL+jquery I have 2 tables table1 table 1 have 4 colume (id, title, desc, thumb_img) tabel2 table 2 have 3 colume(id, table1id, img) I just want to compare 2 table with the value of $_get['QS']; and show the records from both (title, desc, img) Looking forward for the help.:)

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  • Django refresh page if change data by other user

    - by Fran Sobrino
    I have a test django app. In one page the test show the same question to all users. I'd like that when a user answers correctly, send a signal to other active user's browser to refresh to the next question. I have been learning about signals in django I learning work with them but I don't now how send the "refresh signal" to client browser. I think that it can do with a javascript code that check if a certain value (actual question) change and if change reload the page but I don't know this language and the information that I find was confused. Can anybody help me? Many Thanks.

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  • When does it make sense to use a map?

    - by kiwicptn
    I am trying to round up cases when it makes sense to use a map (set of key-value entries). So far I have two categories (see below). Assuming more exist, what are they? Please limit each answer to one unique category and put up an example. Property values (like a bean) age -> 30 sex -> male loc -> calgary Presence, with O(1) performance peter -> 1 john -> 1 paul -> 1

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