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  • Correct handling of return data

    - by Serhiy
    Hello, I have a question related to correct handling of returns of the DAO library I'm writing for one project. This library probably is going to be used by another people and I want to do it correctly. So I would like to know, how I should deal with return statements of the functions of my DAO. Example 1 I have function to getCustomer which should return String. In case query doesn't return any result should I return null, empty string or throw some kind of Exception? Example 2 I have function getCutomerList which return ArrayList. In case query doesn't return any result should I return null, empty ArrayList or throw some Exception? Example 3 Some sql exception was detected, what should I do: throw exception or do try..catch of the block where it can occur? What is the "good" practice or "best" practice to apply in my case? Thanks on advance, Serhiy.

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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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  • Rogue PropertyChanged notifications from ViewModel

    - by user1886323
    The following simple program is causing me a Databinding headache. I'm new to this which is why I suspect it has a simple answer. Basically, I have two text boxes bound to the same property myString. I have not set up the ViewModel (simply a class with one property, myString) to provide any notifications to the View for when myString is changed, so even although both text boxes operate a two way binding there should be no way that the text boxes update when myString is changed, am I right? Except... In most circumstances this is true - I use the 'change value' button at the bottom of the window to change the value of myString to whatever the user types into the adjacent text box, and the two text boxes at the top, even although they are bound to myString, do not change. Fine. However, if I edit the text in TextBox1, thus changing the value of myString (although only when the text box loses focus due to the default UpdateSourceTrigger property, see reference), TextBox2 should NOT update as it shouldn't receive any updates that myString has changed. However, as soon as TextBox1 loses focus (say click inside TextBox2) TextBox2 is updated with the new value of myString. My best guess so far is that because the TextBoxes are bound to the same property, something to do with TextBox1 updating myString gives TextBox2 a notification that it has changed. Very confusing as I haven't used INotifyPropertyChanged or anything like that. To clarify, I am not asking how to fix this. I know I could just change the binding mode to a oneway option. I am wondering if anyone can come up with an explanation for this strange behaviour? ViewModel: namespace WpfApplication1 { class ViewModel { public ViewModel() { _myString = "initial message"; } private string _myString; public string myString { get { return _myString; } set { if (_myString != value) { _myString = value; } } } } } View: <Window x:Class="WpfApplication1.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:WpfApplication1" Title="MainWindow" Height="350" Width="525"> <Window.DataContext> <local:ViewModel /> </Window.DataContext> <Grid> <!-- The culprit text boxes --> <TextBox Height="23" HorizontalAlignment="Left" Margin="166,70,0,0" Name="textBox1" VerticalAlignment="Top" Width="120" Text="{Binding Path=myString, Mode=TwoWay}" /> <TextBox Height="23" HorizontalAlignment="Left" Margin="166,120,0,0" Name="textBox2" VerticalAlignment="Top" Width="120" Text="{Binding Path=myString, Mode=TwoWay}"/> <!--The buttons allowing manual change of myString--> <Button Name="changevaluebutton" Content="change value" Click="ButtonUpdateArtist_Click" Margin="12,245,416,43" Width="75" /> <Button Content="Show value" Height="23" HorizontalAlignment="Left" Margin="12,216,0,0" Name="showvaluebutton" VerticalAlignment="Top" Width="75" Click="showvaluebutton_Click" /> <Label Content="" Height="23" HorizontalAlignment="Left" Margin="116,216,0,0" Name="showvaluebox" VerticalAlignment="Top" Width="128" /> <TextBox Height="23" HorizontalAlignment="Left" Margin="116,245,0,0" Name="changevaluebox" VerticalAlignment="Top" Width="128" /> <!--simply some text--> <Label Content="TexBox1" Height="23" HorizontalAlignment="Left" Margin="99,70,0,0" Name="label1" VerticalAlignment="Top" Width="61" /> <Label Content="TexBox2" Height="23" HorizontalAlignment="Left" Margin="99,118,0,0" Name="label2" VerticalAlignment="Top" Width="61" /> </Grid> </Window> Code behind for view: namespace WpfApplication1 { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { ViewModel viewModel; public MainWindow() { InitializeComponent(); viewModel = (ViewModel)this.DataContext; } private void showvaluebutton_Click(object sender, RoutedEventArgs e) { showvaluebox.Content = viewModel.myString; } private void ButtonUpdateArtist_Click(object sender, RoutedEventArgs e) { viewModel.myString = changevaluebox.Text; } } }

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  • Google Data Api returning an invalid access token

    - by kingdavies
    I'm trying to pull a list of contacts from a google account. But Google returns a 401. The url used for requesting an authorization code: String codeUrl = 'https://accounts.google.com/o/oauth2/auth' + '?' + 'client_id=' + EncodingUtil.urlEncode(CLIENT_ID, 'UTF-8') + '&redirect_uri=' + EncodingUtil.urlEncode(MY_URL, 'UTF-8') + '&scope=' + EncodingUtil.urlEncode('https://www.google.com/m8/feeds/', 'UTF-8') + '&access_type=' + 'offline' + '&response_type=' + EncodingUtil.urlEncode('code', 'UTF-8') + '&approval_prompt=' + EncodingUtil.urlEncode('force', 'UTF-8'); Exchanging the returned authorization code for an access token (and refresh token): String params = 'code=' + EncodingUtil.urlEncode(authCode, 'UTF-8') + '&client_id=' + EncodingUtil.urlEncode(CLIENT_ID, 'UTF-8') + '&client_secret=' + EncodingUtil.urlEncode(CLIENT_SECRET, 'UTF-8') + '&redirect_uri=' + EncodingUtil.urlEncode(MY_URL, 'UTF-8') + '&grant_type=' + EncodingUtil.urlEncode('authorization_code', 'UTF-8'); Http con = new Http(); Httprequest req = new Httprequest(); req.setEndpoint('https://accounts.google.com/o/oauth2/token'); req.setHeader('Content-Type', 'application/x-www-form-urlencoded'); req.setBody(params); req.setMethod('POST'); Httpresponse reply = con.send(req); Which returns a JSON array with what looks like a valid access token: { "access_token" : "{access_token}", "token_type" : "Bearer", "expires_in" : 3600, "refresh_token" : "{refresh_token}" } However when I try and use the access token (either in code or curl) Google returns a 401: curl -H "Authorization: Bearer {access_token}" https://www.google.com/m8/feeds/contacts/default/full/ Incidentally the same curl command but with an access token acquired via https://code.google.com/oauthplayground/ works. Which leads me to believe there is something wrong with the exchanging authorization code for access token request as the returned access token does not work. I should add this is all within the expires_in time frame so its not that the access_token has expired

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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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  • Ruby on Rails : How can i display data for the current view from a different table

    - by krishkule
    This might be a easy-to-answer question, but its a pain in the bum for me.... So... I have two tables - Chords - |id|chord|name|rating|artist_id| Artists - |id|artist| (the relations : chords : belongs_to :artist artists : has_many :chords ) And in the index page for "chords" i want to display chord,name,rating from Chords table AND artist from the Artists table this is the code for the chrod's index.html.erb : <table border="1"> <%@chords.each do |chord|%> <tr> <td><%=chord.artist.artist%></td> <td><%= link_to chord.name, chord %></td> <td><%=chord.rating%></td> <td><%= chord.created_at %></td> </tr> <%end%> </table> The error message is : undefined method `artist' for nil:NilClass Actually, at first it worked, but when i started to create the "new.html.erb" page and the create,new controllers, it stopped working - thats why this is so confusing for me! I will be glad to hear any critique and suggestions! Thank you

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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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  • 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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  • 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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  • 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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  • 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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  • 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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  • Consume a JSON webservice and process data in Android

    - by user1783391
    I am trying to consume a the webservice below http://62.253.195.179/disaster/webservices/login.php?message=[{"email":"[email protected]","password":"welcome"}] This returns a JSON array [{"companyuserId":"2","name":"ben stein","superiorname":"Leon","departmentId":"26","departmentname":"Development","companyId":"23","UDID":"12345","isActive":"1","devicetoken":"12345","email":"[email protected]","phone":"5456465465654","userrole":"1","chngpwdStatus":"1"}] My code is below try{ String weblink = URLEncoder.encode("http://62.253.195.179/disaster/webservices/login.php?message=[{\"email\":\"[email protected]\",\"password\":\"welcome\"}]"); HttpParams httpParameters = new BasicHttpParams(); int timeoutConnection = 7500; HttpConnectionParams.setConnectionTimeout(httpParameters, timeoutConnection); int timeoutSocket = 7500; HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket); HttpClient client = new DefaultHttpClient(httpParameters); HttpGet request = new HttpGet(); URI link = new URI(weblink); request.setURI(link); HttpResponse response = client.execute(request); BufferedReader rd = new BufferedReader(new InputStreamReader( response.getEntity().getContent())); result = rd.readLine(); JSONObject myData = new JSONObject(result); JSONArray jArray = myData.getJSONArray(""); JSONObject steps = jArray.getJSONObject(0); String name = steps.getString("name"); } catch (JSONException e) { e.printStackTrace(); } But its not working and I am not 100% sure this is the best way to do it. 11-10 10:49:55.489: E/AndroidRuntime(392): java.lang.IllegalStateException: Target host must not be null, or set in parameters.

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  • how to handle empty selection in a jface bound combobox?

    - by guido
    I am developing a search dialog in my eclipse-rcp application. In the search dialog I have a combobox as follows: comboImp = new CCombo(grpColSpet, SWT.BORDER | SWT.READ_ONLY); comboImp.setBounds(556, 46, 184, 27); comboImpViewer = new ComboViewer(comboImp); comboImpViewer.setContentProvider(new ArrayContentProvider()); comboImpViewer.setInput(ImpContentProvider.getInstance().getImps()); comboImpViewer.setLabelProvider(new LabelProvider() { @Override public String getText(Object element) { return ((Imp)element).getImpName(); } }); Imp is a database entity, ManyToOne to the main entity which is searched, and ImpContentProvider is the model class which speaks to embedded sqlite database via jpa/hibernate. This combobox is supposed to contain all instances of Imp, but to also let empty selection; it's value is bound to a service bean as follows: IObservableValue comboImpSelectionObserveWidget = ViewersObservables.observeSingleSelection(comboImpViewer); IObservableValue filterByImpObserveValue = BeansObservables.observeValue(searchPrep, "imp"); bindingContext.bindValue(comboImpSelectionObserveWidget, filterByImpObserveValue , null, null); As soon as the user clicks on the combo, a selection (first element) is made: I can see the call to a selectionlistener i added on the viewer. My question is: after a selection has been made, how do I let the user change his mind and have an empty selection in the combobox? should I add a "fake" empty instance of Imp to the List returned by the ImpContentProvider? or should I implement an alternative to ArrayContentProvider? and one additional related question is: why calling deselectAll() and clearSelection() on the combo does NOT set a null value to the bound bean?

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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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  • 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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  • Compile a binary file for linking OSX

    - by Satpal
    I'm trying to compile a binary file into a MACH_O object file so that it can be linked it into a dylib. The dylib is written in c/c++. On linux the following command is used: ld -r -b binary -o foo.o foo.bin I have tried various option on OSX but to no avail: ld -r foo.bin -o foo.o gives: ld: warning: -arch not specified ld: warning: ignoring file foo.bin, file was built for unsupported file format which is not the architecture being linked (x86_64) An empty .o file is created ld -arch x86_64 -r foo.bin -o foo.o ld: warning: ignoring file foo.bin, file was built for unsupported file format which is not the architecture being linked (x86_64) Again and empty .o file is created. Checking the files with nm gives: nm foo.o nm: no name list The binary file is actually, firmware that will be downloaded to an external device. Thanks for looking

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  • Iterative printing over two data types in Python

    - by old Ixfoxleigh
    I often browse freely-available art on the web. Actually, I can't think of a better use for the internet than to turn it into a gigantic art gallery. When I encounter a set of pieces I quite like, I download them all to my hard drive. wget makes that easy, especially in combination with Python's print function, and I use this all the time to make a list of URLs that I then wget. Say I need to download a list of jpegs that run from art0 to art100 in the directory 'art,' I just tell python for i in range(0,101): print "http://somegallery/somedirectory/art", i So, this is probably a fairly simple operation in Python, and after a find-and-replace to remove whitespace, it's just a matter of using wget -i, but in days before I knew any Python I'd slavishly right-click and save. Now I've got a bunch of files from Fredericks & Freiser gallery in New York that all go a(1-14), b(1-14), c(1-14), etc., up to the letter g. I could do that in 7 goes, and it would take me less time than it took to write this SO question. That said, I want to deepen my knowledge of Python. So, given the letters a-g, how do I print a mapping of each letter to the integers 1-14?

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  • ASP.NET - Update progress while processing data

    - by Danny
    Hope I can explain this correctly. I have a process, that outputs step by step messages (i.e., Processing item 1... Error in item 2 etc etc). I want this to be outputted to the user during the process, and not at the end. I pretty sure i need to do this with threading, but can't find a decent example. Thanks in advanced.

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  • Reading file data during form's clean method

    - by Dominic Rodger
    So, I'm working on implementing the answer to my previous question. Here's my model: class Talk(models.Model): title = models.CharField(max_length=200) mp3 = models.FileField(upload_to = u'talks/', max_length=200) Here's my form: class TalkForm(forms.ModelForm): def clean(self): super(TalkForm, self).clean() cleaned_data = self.cleaned_data if u'mp3' in self.files: from mutagen.mp3 import MP3 if hasattr(self.files['mp3'], 'temporary_file_path'): audio = MP3(self.files['mp3'].temporary_file_path()) else: # What goes here? audio = None # setting to None for now ... return cleaned_data class Meta: model = Talk Mutagen needs file-like objects - the first case (where the uploaded file is larger than the size of file handled in memory) works fine, but I don't know how to handle InMemoryUploadedFile that I get otherwise. I've tried: # TypeError (coercing to Unicode: need string or buffer, InMemoryUploadedFile found) audio = MP3(self.files['mp3']) # TypeError (coercing to Unicode: need string or buffer, cStringIO.StringO found) audio = MP3(self.files['mp3'].file) # Hangs seemingly indefinitely audio = MP3(self.files['mp3'].file.read()) Is there something wrong with mutagen, or am I doing it wrong?

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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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