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• How to create program that can be run by: #service myservice start

  - by Saif Bechan

  I am new to Linux and want to know what kind of programs can be run by using. #service myservice start And the programs stays on until stopped. Are they normal c++ programs or are they different. In some tutorials i have seen that they use ./myprogram to start a program. Another thing I have seen is the usage of .sh files. One last type of program i see is executed by the command: #/usr/bin/myprogramm Can someone explain the difference between these or point me to a basic tutorial/guide.

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• Confusing rails div id naming

  - by RailAddict

  I have started using jQuery and rails. I have made a simple form that submits to the database and updates the page without reloading with ajax. In my jQuery functions I used $"#new_comment" for the id name (in my application.js and create.js.erb files) but on my articles/show view file, I named the div "add_comment" and it works.. I renamed it new_comment and it breaks! Can someone explain it please? I get an error: "no action responded to 1" My function in my controller is "create".

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• Help on QStackedWidget

  - by Surjya Narayana Padhi

  Hi Geeks, I am using a QStackedWidget on my mainWindow. The firstPageWidget on stackedWidget contains 3 buttons. Now If I will press the first button on firstPage, I want the stackedWidget show the 2nd Page widget. Following are the details I tried to connect like this in my mainwindow connect(firstPageWidget->button1,SIGNAL(clicked()),stackWidget,SLOT(setCurrentIndex(int))); Now I want to know how to pass the value of index number to stackWidget to set currentIndex? If my question is not much clear please tell me I will explain more.

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• How can I make a career in Formal Methods programming in USA?

  - by A5al Andy

  I've found that my (USA) professors recoil with a near-disgust when I ask them about how to pursue a career in Formal Methods programming. They say, "Oh, that stuff! That stuff is anal. You don't need that European POS to get a job." I'm sure I'll get a job without it, but Formal Methods interests me so much that I bet I'd like to make a career of it. I'd like to learn about Formal Methods at an American University and then work in that field here. I've found that even professors at more important universities than mine don't seem to welcome Formal Methods. Almost all FM research project webpages are semi-abandoned and moldering. Europe is where the action seems to be for this. Can anyone suggest a plan of attack, and along the way explain the antipathy to Formal Methods in the US? I'm a sophomore at a public university in the South.

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• MAD method compression function

  - by Jacques

  I ran across the question below in an old exam. My answers just feels a bit short and inadequate. Any extra ideas I can look into or reasons I have overlooked would be great. Thanx Consider the MAD method compression function, mapping an object with hash code i to element [(3i + 7)mod9027]mod6000 of the 6000-element bucket array. Explain why this is a poor choice of compression function, and how it could be improved. I basically just say that the function could be improved by changing the value for p (or 9027) to an prime number and choosing an other constant for a (or 3) could also help.

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• Tarballing without git metadata

  - by zaf

  My source tree contains several directories which are using git source control and I need to tarball the whole tree excluding any references to the git metadata or custom log files. I thought I'd have a go using a combo of find/egrep/xargs/tar but somehow the tar file contains the .git directories and the *.log files. This is what I have: find -type f . | egrep -v '\.git|\.log' | xargs tar rvf ~/app.tar Can someone explain my misunderstanding here? Why is tar processing the files that find and egrep are filtering? I'm open to other techniques as well.

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• Netbeans GUI editor generating its own incomprehensible code.

  - by WarDoGG

  When creating a new project in netbeans, if i select JAVA Desktop application, it creates some code which I DO NOT RECOGNISE AT ALL as what i had learnt in swing. It imports packages such as : org.jdesktop.application.SingleFrameApplication; also, the declaration for main() looks like this : public static void main(String[] args) { launch(DesktopApplication2.class, args); } This really does not make any sense to my knowledge of JFrame, JPanel etc.. If i try to code a netbeans application from scratch, i can write my own swing app BUT I CANNOT FIND THE GUI EDITOR. How do i bring the GUI editor when creating java application from scratch ? Can anyone explain to me this org.jdesktop.application.SingleFrameApplication and other classes ? Please help. This is really frustrating.

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• Unit Test ouput in MSBuild/TFS 2008

  - by Adam Jenkin

  I have a build in TFS 2008 which includes the running of a UnitTest project. I have configured my build as such that in the drop folder after each build, I get a StyleCop.log, FxCop.log and would like to place the trx or output from the unit tests here also. I can see that my unit tests are running as part of the build, however currently I cannot find were the output is saved to or find a way of setting the ouput to my drop location ($(DropLocation)\$(BuildNumber)\MyUnitTests.txt) My unit tests are included by using the following:- <RunTest>true</RunTest> ... <ItemGroup> <TestContainer Include="$(OutDir)\%2aMyUnitTests.dll" /> </ItemGroup> Can somebody help explain how I can achieve this.

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• Why is it preferable to call a static method statically from within an instance of the method's clas

  - by javanix

  If I create an instance of a class in Java, why is it preferable to call a static method of that same class statically, rather than using this.method()? I get a warning from Eclipse when I try to call static method staticMethod() from within the custom class's constructor via this.staticMethod(). public MyClass() { this.staticMethod(); } vs public MyClass() { MyClass.staticMethod(); } Can anyone explain why this is a bad thing to do? It seems to me like the compiler should already have allocated an instance of the object, so statically allocating memory would be unneeded overhead.

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• Interacting with system commands using a web dev language

  - by Jamie

  Hi all, First of all, sorry for the vague title. Let me explain. At work we're currently using SunGrid I've been assigned a project to create a web interface wrapper for interacting with the engine. i.e. displaying users jobs, submitting jobs via a nice GUI etc. (most of the sgrid commands output xml which is nice) My question for you chaps is the following: What web dev language would you use to interact with the system? i.e. use the language to do a system call and evaluate the response. I'm not after an argument on which language is best, I just would like to know which language is specifically good for interacting with the system and is also good for web dev.

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• Accessing structure elements using pointers

  - by Arun Nadesh

  Hi Everybody, Greetings! I got surprised when the following program did not crash. typedef struct _x{ int a; char b; int c; }x; main() { x *ptr=0; char *d=&ptr->b; } As per my understanding the -> operator has higher precedence over & operator. So I expected the program to crash at the below statement when we try to dereference the NULL pointer tr. char *d=&ptr->b; But the statement &ptr->b evaluates to a valid address. Could somebody please explain where I'm wrong? Thanks & Regards, Arun

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• Java method overloading + double dispatch

  - by Max

  Can anybody explain in detail the reason the overloaded method print(Parent parent) is invoked when working with Child instance in my test piece of code? Any pecularities of virtual methods or methods overloading/resolution in Java involved here? Any direct reference to Java Lang Spec? Which term describes this behaviour? Thanks a lot. public class InheritancePlay { public static class Parent { public void doJob(Worker worker) { System.out.println("this is " + this.getClass().getName()); worker.print(this); } } public static class Child extends Parent { } public static class Worker { public void print(Parent parent) { System.out.println("Why this method resolution happens?"); } public void print(Child child) { System.out.println("This is not called"); } } public static void main(String[] args) { Child child = new Child(); Worker worker = new Worker(); child.doJob(worker); } }

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• Unable to reverse seemingly simple rails migration - getting "altered_table.column may not be NULL"

  - by brad

  I have a table 'invoices' in my development database (sqlite3) populated with a small amount of test data. I wanted to add a column 'invoice_number' to it and set up a migration like so: class AddInvoiceNumberColumnToInvoices < ActiveRecord::Migration def self.up add_column :invoices, :invoice_number, :integer end def self.down remove_column :invoices, :invoice_number end end I ran rake db:migrate and it seemed to migrate just fine. However, when I tried to access this column through ActiveRecord it didn't seem to be there. I decided to undo this migration and try again (not sure what I was going to try but I thought I'd start by undoing it) with rake db:migrate VERSION='whatever_the_migration_before_this_one_was_called'. This failed with the error message == AddInvoiceNumberColumnToInvoices: reverting =============================== -- remove_column(:invoices, :invoice_number) rake aborted! An error has occurred, this and all later migrations canceled: altered_invoices.invoice_number may not be NULL I can't find any documentation of this error. Is anyone able to explain what I have done wrong, and more importantly how I can fix this?

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• JDBC query to Oracle

  - by Harish

  Hi, We are planning to migrate our DB to Oracle.We need to manually check each of the embedded SQL is working in Oracle as few may follow different SQL rules.Now my need is very simple. I need to browse through a file which may contain queries like this. String sql = "select * from test where name="+test+"and age="+age; There are nearly 1000 files and each file has different kind of queries like this where I have to pluck the query alone which I have done through an unix script.But I need to convert these Java based queries to Oracle compatible queries. ie. select * from test where name="name" and age="age" Basically I need to check the syntax of the queries by this.I have seen something like this in TOAD but I have more than 1000 files and can't manually change each one.Is there a way? I will explain more i the question is not clear

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• How to calculate order (big O) for more complex algorithms (ie quicksort)

  - by bangoker

  I know there are quite a bunch of questions about big O notation, I have already checked Plain english explanation of Big O , Big O, how do you calculate/approximate it?, and Big O Notation Homework--Code Fragment Algorithm Analysis?, to name a few. I know by "intuition" how to calculate it for n, n^2, n! and so, however I am completely lost on how to calculate it for algorithms that are log n , n log n, n log log n and so. What I mean is, I know that Quick Sort is n log n (on average).. but, why? Same thing for merge/comb, etc. Could anybody explain me in a not to math-y way how do you calculate this? The main reason is that Im about to have a big interview and I'm pretty sure they'll ask for this kind of stuff. I have researched for a few days now, and everybody seem to have either an explanation of why bubble sort is n^2 or the (for me) unreadable explanation a la wikipedia Thanks!

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• [Java] Flood fill using a stack

  - by dafero

  Hello to everyone :), I am using the recursive Flood fill algorithm in Java to fill some areas of a image. With very small images it works fine, but when de image becomes larger the JVM gives me a Stack Over Flow Error. That's the reason why I have to reimplement the method using a Flood Fill with my own stack. (I read that's the best way to do it in these kind of cases) Can anyone explain me how to code it? (if you don't have the code at hand, with the pseudo-code of the algorithm will be fine) I've read a lot in the Internet but I haven't understood it very well. Thanks!

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• Facebox adding commas to input

  - by Ed Woodcock

  I'm using a facebox to display a form inside a lightbox, nothing too exciting (just a couple of datepickers, some textboxes and a checkbox). However, I'm having issues with the postbacks, whenever I post back from the facebox it adds a ',' to the start of the input (so "rabbit" becomes ",rabbit") Now, I saw that there was the same issue with the modalpopup extender from the ajaxcontroltoolkit, so I assume it's a common issue. Can anyone either explain why this is happening, or tell me how to fix it? provide a decent way of fixing this? I have actually done it, and it works very nicely, but I don't really want to answer my own bounty question so someone else give it a go! Cheers, Ed EDIT See attached answer for a correct solution (I fixed this eventually but didn't want to ruin the bounty question so left the answer until afterwards).

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• Using Dijkstra's algorithm with negative edges?

  - by Riddler

  Most books explain the reason the algorithm doesn't work with negative edges as nodes are deleted from the priority queue after the node is arrived at since the algorithm assumes the shortest distance has been found. However since negative edges can reduce the distance, a future shorter distance might be found; but since the node is deleted it cannot be updated. Wouldn't an obvious solution to this be to not delete the node? Why not keep the node in the queue, so if a future shorter distance is found, it can be updated? If I am misunderstanding the problem, what is preventing the algorithm from being used with negative edges?

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• Left Join 3 Tables and Show True or False on Empty Cells

  - by Jason Shultz

  Ok, this may be confusing so I hope I explain it correctly. I have 4 tables: business photos video category I want to display "featured" businesses on the home page (or elsewhere) and I want to show a Yes or No in the table row based upon whether or not there are photos or videos for that business. Example: Joes Crab Shack has no videos or photos but is featured. So, when his row is echoed out it will show the Business Name and Business Owner but there will be no data in the photo or video cells thus in the video and photos column it will say No. Otherwise, if the opposite was true, it would say Yes. Here's my pastebin

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• Screen Capture with Open GL using glReadPixels

  - by Raja

  Hi, I created a CGRegisterScreenRefreshCallback(refreshCallback, NULL) and in the refreshCallback method get the list of rectangles which have changed. I am getting the rectangle data from frameBuffer using OpenGL glReadPixels. Is there a better way of screen capture either with/without opengl and also using OpenGL can I skip reading pixel by pixel ? I have looked at glGetTexImage and glCopyTexSubImage2D. Any simple code block which can explain how to use these functions to get the changed rectangle data would be very helpful ? Thanks, Raja.

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• Creating a System.Web.UI.Page programatically in IHTTPHandler

  - by ObiWanKenobi

  I am trying to use the ASP.NET (3.5) "Routing Module" functionality to create custom pages based on the contents of the URL. Various articles, such as this one: http://blogs.msdn.com/mikeormond/archive/2008/05/14/using-asp-net-routing-independent-of-mvc.aspx explain how to use ASP.NET Routing to branch to existing pages on the web server. What I would like to do is create the page on-the-fly using code. My first attempt looks like this: public class SimpleRouteHandler : IRouteHandler { public IHttpHandler GetHttpHandler(RequestContext requestContext) { string pageName = requestContext.RouteData.GetRequiredString("PageName"); Page myPage = new Page(); myPage.Response.Write("hello " + pageName); return myPage; } } But this throws an HTTPException saying "Response is not available in this context." at the Response.Write statement. Any ideas on how to proceed? UPDATE: In the end, I went with an approach based on IHttpModule, which turned out to be rather easy.

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• ActiveX controls with old Delphi versions

  - by DamienD

  I'm testing a non visual ActiveX control based on a registered .ocx which I import into Delphi using the provided wizard. Then, I simply put the generated component on the main form of a new VCL application. Under old Delphi versions (D5 and D2007), when i launch the application, this raise an AV during the component initialization. with Delphi 2009 : no problem, the application starts smoothly. My questions are : Are there known enhancements of ActiveX management in recent Delphi versions which can explain this difference ? Can I suspect a bug in the ActiveX control, or can I consider the origin of the problem is from old Delphi versions ? I need to use this component (if tests OK) in D2007. Do you think that it is possible to correct the AV problem under D2007 by modifying the D2007 generated .tlb file (for example by trying to use the D2009 generated one) PS: the ActiveX control is not named, because my question is a general question about Delphi and ActiveX, not about a specific ActiveX control.

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• How do I setup a Master Page with ASP.net?

  - by Michael

  Hi there, I'm normally a ColdFusion developer, but I'm having to work on a new site using some ASP.net hosting only, so forgive me if my questions seem very trivial. For numerous reasons, the website will be relatively static in the sense that it will mainly be using includes etc...that's about as complex as it will get with this. Now, I heard about the ability to set a master in ASP.net. Would anyone please be able to explain to me in a step process on how to do this? I have of course been searching for some time now on this topic but most results yield little help or no help at all since the search terms are slightly ambiguous. It would be nice to have this functionality for the long run. Any help or advice would be great. Many thanks. Michael.

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• iPad UISPlitViewController question

  - by saikamesh

  Hi, It is mentioned in the Apple's documentation that if we use UISPlitViewController in our app, then that should be the root view controller. In our iPone app we are showing splash screen for some seconds till the loading of the app finishes. Once it is loaded the home screen needs to be displayed in a SplitViewController. If we use SplitViewController as the root view. How will we show the splash screen which is displayed in a single view where as SplitVieController displays two ViewControllers. Please explain me the how this can be done.

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• Unbelievable: Cannot cast from class X to its super class

  - by Phuong Nguyen de ManCity fan

  I'm encountering a very weird problem with Spring (3.0.1.RELEASE), TestNG (5.11) and Maven Surefire (2.5). I have a test class that extends a Spring helper class for testNG so that test context can be loaded from an xml file (that contains some bean definitions). My project was imported into eclipse using m2eclipse (using Import Maven Project) The class run fine in Eclipse TestNG runner. However, it throws this exception with Maven Surefire Caused by: java.lang.ClassCastException: com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl cannot be cast to javax.xml.parsers.DocumentBuilderFactory at javax.xml.parsers.DocumentBuilderFactory.newInstance(DocumentBuilderFactory.java:123) at org.springframework.beans.factory.xml.DefaultDocumentLoader.createDocumentBuilderFactory(DefaultDocumentLoader.java:89) at org.springframework.beans.factory.xml.DefaultDocumentLoader.loadDocument(DefaultDocumentLoader.java:70) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:388) I have eliminated all involved dependencies in my pom so that the two classes com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl and javax.xml.parsers.DocumentBuilderFactory are coming from JRE only (the rt.jar). So, it looks so unbelievable to me. I wonder if there is any mechanism in loading class that can explain for this behavior? Thanks.

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