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  • OpenCv not initializing usb camera

    - by brainbarshan
    I am trying to capture video from usb camera using OpenCv. #include <highgui.h> #include <iostream> using namespace std; using namespace cv ; int main() { VideoCapture cap (-1); if(!cap.isOpened()) cout << "Cam initialize failed" ; else cout << "Cam initialized" ; return 0; } It is failing to initialize the camera. cap.isOpened() is returning zero. The same program, with same version of OpenCv and same usb camera, is correctly running in my friend's machine. I am running fedora 16. I did some searching in Google and Stack Overflow. But no useful help. Any idea ?

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  • Do I still have to implement a singleton class by hand in .net, even when using .Net4.0?

    - by Hamish Grubijan
    Once the singleton pattern is understood, writing subsequent singleton classes in C# is a brainless exercise. I would hope that the framework would help you by providing an interface or a base class to do that. Here is how I envision it: public sealed class Schablone : ISingleton<Schablone> { // Stuff forced by the interface goes here // Extra logic goes here } Does what I am looking for exist? Is there some syntactic sugar for constructing a singleton class - whether with an interface, a class attribute, etc.? Can one write a useful and bullet-proof ISingleton themselves? Care to try? Thanks!

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  • Has anybody used the WB B-tree library?

    - by Chris B
    I stumbled across the WB on-disk B-tree library: http://people.csail.mit.edu/jaffer/WB It seems like it could be useful for my purposes (swapping data to disk during very large statistical calculations that do not fit in memory), but I was wondering how stable it is. Reading the manual, it seems worringly 'researchy' - there are sections labelled [NOT IMPLEMENTED] etc. But maybe the manual is just out-of-date. So, is this library useable? Am I better off looking at Tokyo Cabinet, MemcacheDB, etc.? By the way I am working in Java.

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  • High level programming logic, design, pattern

    - by Muhammad Shahzad
    I have been doing programming from last 7 years, getting better and better, but still i think that am lacking something. I have been doing work in JOOMLA, MAGENTO, WP, Custom PHP, Opencart, laravel, codeignitor. Sometimes i need to design logic for a huge database application, in the applications we need nesting loops and queries, although i follow OOPS standards, ORM etc, still i feel i need more robust coding designs. I need to know how can i improve these things, so that code remain neat, efficient and faster. Also how big webapps like facebook twitter tests there code speed? How high level programmers choose design patterns. If you can help me find something useful with examples?

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  • Why use a do-end block in Lua?

    - by Mayron
    I keep trying to find answers for this but fail to do so. I wanted to know, what is the do-end block actually used for? It just says values are used when needed in my book so how could I use this? Do I use it to reduce the scope of local variables by placing a function in a do-end loop and place local variables outside of the function but inside this do-end block and the variables will be seen by the function? But then can the function still be called? Sorry for being very vague. I hope that makes sense. Maybe an illustrated example might be useful ^^

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  • Setting breakpoint in c# code with ADPlus

    - by Petr Havlicek
    Hello, I am wondering if it is possible to set a breakpoint in C# code using ADPlus. I find several examples of config files but they always works with native code. Like this one: <ADPlus> <Breakpoints> <NewBP> <!-- Set the breakpoint on ExitProcess. --> <Address>kernel32!ExitProcess</Address> <Type>BP</Type> <Actions>FullDump;Stacks;</Actions> <ReturnAction>G</ReturnAction> </NewBP> </Breakpoints> </ADPlus> Something like this would be useful: <Address>MyCSharpClass.SomeMethod</Address>

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  • How can I tell Visual Studio to not catch a particular exception?

    - by Noel Kennedy
    I have a particular type of exception that I would like Visual Studio to not catch with the Exception Assistant. Essentially I would like it just to let my normal exception handling infrastructure deal with it. The exception is an inheritor of System.Exception which I wrote and have the source code for. Any where this is thrown I want VS to not catch it, ie it is not useful to just supress a single throw new BlahException(); in code. This is because the exception is thrown a lot, and I don't want to have to supress every single instance individually. In case it makes a difference I am on Visual Studio 2010 Ultimate, Framework 3.5 SP1.

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  • AsyncTask Threading Rule - Can it really only be used once?

    - by stormin986
    In the documentation on AsyncTask it gives the following as a rule related to threading: The task can be executed only once (an exception will be thrown if a second execution is attempted.) All this means is that you have to create a new instance of the class every time you want to use it, right? In other words, it must be done like this: new DownloadFilesTask().execute(url1, url2, url3); new DownloadFilesTask().execute(url4, url5, url6); Or conversely, you can NOT do the following: DownloadFilesTask dfTask = new DownloadFilesTask(); dfTask().execute(url1, url2, url3); dfTask().execute(url4, url5, url6); Can someone verify this is an accurate interpretation? I realize I pretty much just answered this for myself as I was typing this out... But it wasn't immediately obvious to me so I think this would be useful to have posted nonetheless.

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  • Is it possible to create nested classes in PHP as it is in C#?

    - by Edward Tanguay
    In C# you can have nested classes like this, which are useful if you have classes which do not have meaning outside the scope of one particular class, e.g. in a factory pattern: public abstract class BankAccount { private BankAccount() {} private sealed class SavingsAccount : BankAccount { ... } private sealed class CheckingAccount : BankAccount { ... } public BankAccount MakeSavingAccount() { ... } public BankAccount MakeCheckingAccount() { ... } } Is this possible in PHP? I've read that it was planned for PHP 5, then cancelled, then planned again, but can't find definitive info. Does anyone know how to create nested classes (classes within the scope of another class) as in the above C# example using PHP 5.3?

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  • Java - understanding servlets

    - by Trup
    I am working on a homework project that should implement a board game between 2 clients over an HttpServlet. I have couple of questions: 1) I read that HttpServlets must be stateless, however, for the sake of the game, I have to keep a lot of state(whose turn it is, the state of the board, etc). Do I have to keep this in the clients? Does the HttpServlet indeed have to be stateless, i.e. have no fields that track state? 2) I know that the clients will talk to the servlet via the doGet/doPost methods, but how can the servlet talk to the clients(for example, if player 1 just made a move and sent it to the servlet, the servlet has to tell client 2 what the move was). Thank you Also, if you can point me to a useful, simple example of a similar code online, I would be very grateful

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  • VB.NET Window Screen Capture (ALT+PRINTSCREEN)

    - by Steve Thomas
    Hi, I found that code somewhere and I find it quite useful but I would like to find a way to make it work so it capture only the given window target. Maybe with a processID or Window Name. Even if that window is not active. I do not want to make that window active but want to get a screen capture like if I was doing Alt+PrintScreen on it. Here is the code that works for full Screen Capture Private bmpScreenShot As Bitmap Private gfxScreenshot As Graphics bmpScreenShot = New Bitmap(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height, PixelFormat.Format32bppArgb) gfxScreenshot = Graphics.FromImage(bmpScreenShot) gfxScreenshot.CopyFromScreen(Screen.PrimaryScreen.Bounds.X, Screen.PrimaryScreen.Bounds.Y, 0, 0, Screen.PrimaryScreen.Bounds.Size, CopyPixelOperation.SourceCopy) bmpScreenShot.Save(fileName, ImageFormat.Png) I use the Visual Basic 2008 Express Thank you in advance!

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  • How do you keep track of what the industry is up to?

    - by BlairHippo
    A discussion elsewhere made me realize that I don't do a particularly good job of following the software industry. My exposure to new trends or technologies is haphazard at best, often limited to a "Hey, that sounds interesting" when I see people discussing something I'm not familiar with on SO. To abuse a metaphor, I'm quite familiar with the tree where I work, but I know too bloody little about the rest of the forest. How do other folks keep abreast of what's going on in the software industry? Are there any sites/blogs/podcasts/whatever that you find particularly valuable for keeping you informed of potentially useful new technologies or industry-wide trends? (My apologies in advance if this is a duplicate; this feels like something that ought to have been asked before, but alas, my search-fu has failed me.)

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  • An analog of String.Join(string, string[]) for List<T> or other generic enumerable

    - by abatishchev
    class String contains very useful method - String.Join(string, string[]). It creates a string from an array, separating each element of array with a symbol given. But general - it doesn't add a separator after the last element! I uses it for ASP.NET coding for separating with "<br />" or Environment.NewLine. So I want to add an empty row after each row in asp:Table. What method of IEnumerable<TableRow> can I use for the same functionality?

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  • How to get user input for 2 digit data

    - by oneMinute
    In a HTML form user is expect to fill / select some data and trigger an action probably a http-post. If your only requested data field is a "2 digit" you can use html text input element get some data. Then you want to make it useful; enable user easily select data from a 'html select' But not all of your data is well-ordered so eye-searching within these data is somehow cumbersome. Because your data is meaningful with its relations. If there is no primary key for foreign key "12" it should not be shown. Vice versa if this foreign key occurs a lot, then it has some weight and could be displayed with more importance. So, what will be your way? a) Use text input to get data and validate it with regex, javascript, ... b) Use some dropdown select. c) Any other way ? Any answer will appreciated :)

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  • How can I make visual studio 2010 deploy (or FTP upload) a page on save?

    - by Isa
    Just started using Visual Studio 2010, moved over from Netbeans. I kinda liked the Netbeans upload on save functionality, which was useful in development environments when one is constantly making small changes and testing them. As soon as you saved a file, it would be synced to the FTP server. Is it possible to do this in VS? I'm pretty sure there is a way, using a macro of some sort, and having it run on every save? However I have no idea how to implement it... Maybe even a keyboard shortcut to deploy the current working file would be nice.

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  • Scala's lazy arguments: How do they work?

    - by python dude
    In the file Parsers.scala (Scala 2.9.1) from the parser combinators library I seem to have come across a lesser known Scala feature called "lazy arguments". Here's an example: def ~ [U](q: => Parser[U]): Parser[~[T, U]] = { lazy val p = q // lazy argument (for(a <- this; b <- p) yield new ~(a,b)).named("~") } Apparently, there's something going on here with the assignment of the call-by-name argument q to the lazy val p. So far I have not been able to work out what this does and why it's useful. Can anyone help?

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  • PHP vs JSP Which is should I use/learn for my project?

    - by Jon
    I'm planning on making a fitness planning web application for my senior project at school. However, I don't know anything about either technology and my only experience with web development previously was with python and django. I was wondering what people might recommend to learn, what is most useful to learn for the job market, and what would be best for this project. If it matters, the programming languages I know are, C, C++, Java, and Python. My goal of the project is to learn technologies that will make me a more marketable person. Thanks

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  • How can I tell Visual Studio to NOT BREAK on a particular exception?

    - by Noel Kennedy
    I have a particular type of exception that I would like Visual Studio to not catch with the Exception Assistant. Essentially I would like it just to let my normal exception handling infrastructure deal with it. The exception is an inheritor of System.Exception which I wrote and have the source code for. Any where this is thrown I want VS to not catch it, ie it is not useful to just supress a single throw new BlahException(); in code. This is because the exception is thrown a lot, and I don't want to have to supress every single instance individually. In case it makes a difference I am on Visual Studio 2010 Ultimate, Framework 3.5 SP1.

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  • What Use are Threads Outside of Parallel Problems on MultiCore Systesm?

    - by Robert S. Barnes
    Threads make the design, implementation and debugging of a program significantly more difficult. Yet many people seem to think that every task in a program that can be threaded should be threaded, even on a single core system. I can understand threading something like an MPEG2 decoder that's going to run on a multicore cpu ( which I've done ), but what can justify the significant development costs threading entails when you're talking about a single core system or even a multicore system if your task doesn't gain significant performance from a parallel implementation? Or more succinctly, what kinds of non-performance related problems justify threading? Edit Well I just ran across one instance that's not CPU limited but threads make a big difference: TCP, HTTP and the Multi-Threading Sweet Spot Multiple threads are pretty useful when trying to max out your bandwidth to another peer over a high latency network connection. Non-blocking I/O would use significantly less local CPU resources, but would be much more difficult to design and implement.

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  • Most valued skill set in web development industry/what should I be doing now? (Kinda random "career"

    - by Andrew
    I want to be a web programmer [when I grow up?] because it's what I like doing, and I really do thoroughly enjoy it (web development in general, actually). I have about 2 years experience with PHP, CSS, and HTML and a few months experiance with JS and jQuery. I've been wondering this for a while -- what languages should I be most familiar with if I want to try and make a career out of web development? I'm only 17, so I've got plenty of time, and I think I've got a decent headstart on things, but it doesn't hurt to ask. If I'm thinking in terms of being able to get hired as a web programmer, what is (or what are...?) the most useful thing I can do now to be able to have an upper hand when it comes to looking for a job. What languages, as a young programmer, should I really focus on? If you were looking to hire a developer, what would you be looking for?

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  • prevent using functions before initialization, constructors-like in C

    - by Hernán Eche
    This is the way I get to prevent funA,funB,funC, etc.. for being used before init #define INIT_KEY 0xC0DE //any number except 0, is ok static int initialized=0; int Init() { //many init task initialized=INIT_KEY; } int funA() { if (initialized!=INIT_KEY) return 1 //.. } int funB() { if (initialized!=INIT_KEY) return 1 //.. } int funC() { if (initialized!=INIT_KEY) return 1 //.. } The problem with this approach is that if some of those function is called within a loop so "if (initialized!=INIT_KEY)" is called again, and again, although it's not necessary. It's a good example of why constructors are useful haha, If it were an object I would be sure that when was created initialization was called, but in C, I don't know how to do it. Any other ideas are welcome!

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  • Is there any way to do a WER "Request Additional Files" for the windows temp directory?

    - by Jason Mathison
    My company has had numerous crashes reported to windows error reporting due to what looks like an install problem. The logs for our installs are typically in the windows\temp directory. I would like to include the install log file as a "Request Additional Files" entry, however there doesn't seem to be any way to get to a subdirectory of the list of environmental Variables that are provided. The windows temp directory is not in the list of values that you can work from, so I am stuck. In general, I don't understand how it is possible to get at almost anything of use via the "Request Additional Files". For example, the %programfiles% directory shouldn't contain any useful files, they should be in a subdirectory for your product. What am I missing?

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  • Will the <b> and <i> tags ever become deprecated?

    - by CrazyJugglerDrummer
    (This is more of a curiousity question than any pending disaster :D ) So the <b> and <i> tags have been around since near the beginning of the web (I assume). But now we have CSS and many people apposing "stylistic html tags." They are stylistic tags, but they're really not so bad, as they save us from having to make a <span class="bold"> a whole bunch of times, reducing download times. Seeing as they don't take up much space, are easy to use, can possibly be useful to screen-readers, search engines, and other applications that don't care much about how a document looks, and removing them would break TONS of html code, I'm guessing probably not, but I still wanted to bring up the topic. :)

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  • What's the best way to share one Entity Framework 4 data model among multiple applications (meant to

    - by Ivan
    A project (a "solution" to say in VS terms) of mine consists of an ASP.Net 4 Dynamic Data Entities web application, some WinForms applications, some WPF applications, some services. All they are intended to work with one SQL Server database, generated from an Entity Framework 4 model as table-per-type, with lots of inheritance and multiple self-referencing relations. Where do I best put my model? In a separate class library, a copy in every project, in one project, etc. What naming should I best use? Is it good idea to name it MySolution.MyClassLibrary.MySolutionEntities, or just MySolutionEntities or just MySolution? Can you share any useful experience on this subject?

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  • How can the last command's wall time be put in the Bash prompt?

    - by Mr Fooz
    Is there a way to embed the last command's elapsed wall time in a Bash prompt? I'm hoping for something that would look like this: [last: 0s][/my/dir]$ sleep 10 [last: 10s][/my/dir]$ Background I often run long data-crunching jobs and it's useful to know how long they've taken so I can estimate how long it will take for future jobs. For very regular tasks, I go ahead and record this information rigorously using appropriate logging techniques. For less-formal tasks, I'll just prepend the command with time. It would be nice to automatically "time" every single interactive command and have the timing information printed in a few characters rather than 3 lines.

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