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  • Should a new programmer nowadays start with C/C++ or OOP language? [closed]

    - by deviDave
    I've been a programmer for 15+ years. In my time, we all started with C or C++ and then moved to C# or Java. At that time it was a usual practice. Now, my brother wants to follow my steps and I am not sure what advice to give him. So, I am asking the community for an opinion. Should nowadays new programmer with zero programming knowledge start with functional languages (C, C++, etc.) or he should start directly with OOP languages (Java, C#, etc.)? The reply should be considered in the context of my brother's future assignments. He will mainly work on Java mobile applications as well as ASP.NET web apps. He will have to touch with desktop apps, low level programming, drivers, etc. This is the reason I am not sure if he should ever need to learn functional languages.

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  • Scheme vs Haskell for an Introduction to Functional Programming?

    - by haziz
    I am comfortable with programming in C and C#, and will explore C++ in the future. I may be interested in exploring functional programming as a different programming paradigm. I am doing this for fun, my job does not involve computer programming, and am somewhat inspired by the use of functional programming, taught fairly early, in computer science courses in college. Lambda calculus is certainly beyond my mathematical abilities, but I think I can handle functional programming. Which of Haskell or Scheme would serve as a good intro to functional programming? I use emacs as my text editor and would like to be able to configure it more easily in the future which would entail learning Emacs Lisp. My understanding, however, is that Emacs Lisp is fairly different from Scheme and is also more procedural as opposed to functional. I would likely be using "The Little Schemer" book, which I have already bought, if I pursue Scheme (seems to me a little weird from my limited leafing through it). Or would use the "Learn You a Haskell for Great Good" if I pursue Haskell. I would also watch the Intro to Haskell videos by Dr Erik Meijer on Channel 9. Any suggestions, feedback or input appreciated. Thanks. P.S. BTW I also have access to F# since I have Visual Studio 2010 which I use for C# development, but I don't think that should be my main criteria for selecting a language.

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  • How can I assign a name to a task in TPL

    - by mehrandvd
    I'm going to use lots of tasks running on my application. Each bunch of tasks is running for some reason. I would like to name these tasks so when I watch the Parallel Tasks window, I could recognize them easily. With another point of view, consider I'm using tasks at the framework level to populate a list. A developer that use my framework is also using tasks for her job. If she looks at the Parallel Tasks Window she will find some tasks having no idea about. I want to name tasks so she can distinguish the framework tasks from her tasks. It would be very convenient if there was such API: var task = new Task(action, "Growth calculation task") or maybe: var task = Task.Factory.StartNew(action, "Populating the datagrid") or even while working with Parallel.ForEach Parallel.ForEach(list, action, "Salary Calculation Task" Is it possible to name a task? Is it possible to give ???Parallel.ForEach a naming structure (maybe using a lambda) so it creates tasks with that naming? Is there such API somewhere that I'm missing? I've also tried to use an inherited task to override it's ToString(). But unfortunately the Parallel Tasks window doesn't use ToString()! class NamedTask : Task { private string TaskName { get; set; } public NamedTask(Action action, string taskName):base(action) { TaskName = taskName; } public override string ToString() { return TaskName; } }

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  • Parallel.For System.OutOfMemoryException

    - by Martin Neal
    We have a fairly simple program that's used for creating backups. I'm attempting to parallelize it but am getting an OutofMemoryException within an AggregateExcption. Some of the source folders are quite large, and the program doesn't crash for about 40 minutes after it starts. I don't know where to start looking so the below code is a near exact dump of all code the code sans directory structure and Exception logging code. Any advise as to where to start looking? using System; using System.Diagnostics; using System.IO; using System.Threading.Tasks; namespace SelfBackup { class Program { static readonly string[] saSrc = { "\\src\\dir1\\", //... "\\src\\dirN\\", //this folder is over 6 GB }; static readonly string[] saDest = { "\\dest\\dir1\\", //... "\\dest\\dirN\\", }; static void Main(string[] args) { Parallel.For(0, saDest.Length, i => { try { if (Directory.Exists(sDest)) { //Delete directory first so old stuff gets cleaned up Directory.Delete(sDest, true); } //recursive function clsCopyDirectory.copyDirectory(saSrc[i], sDest); } catch (Exception e) { //standard error logging CL.EmailError(); } }); } } /////////////////////////////////////// using System.IO; using System.Threading.Tasks; namespace SelfBackup { static class clsCopyDirectory { static public void copyDirectory(string Src, string Dst) { Directory.CreateDirectory(Dst); /* Copy all the files in the folder If and when .NET 4.0 is installed, change Directory.GetFiles to Directory.Enumerate files for slightly better performance.*/ Parallel.ForEach<string>(Directory.GetFiles(Src), file => { /* An exception thrown here may be arbitrarily deep into this recursive function there's also a good chance that if one copy fails here, so too will other files in the same directory, so we don't want to spam out hundreds of error e-mails but we don't want to abort all together. Instead, the best solution is probably to throw back up to the original caller of copy directory an move on to the next Src/Dst pair by not catching any possible exception here.*/ File.Copy(file, //src Path.Combine(Dst, Path.GetFileName(file)), //dest true);//bool overwrite }); //Call this function again for every directory in the folder. Parallel.ForEach(Directory.GetDirectories(Src), dir => { copyDirectory(dir, Path.Combine(Dst, Path.GetFileName(dir))); }); } }

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  • NHybernate, the Parallel Framework, and SQL Server

    - by andy
    hey guys, we have a loop that: 1.Loops over several thousand xml files. Altogether we're parsing millions of "user" nodes. 2.In each iteration we parse a "user" xml, do custom deserialization 3.finally, in each iteration, we send our object to nhibernate for saving. We use: .SaveOrUpdateAndFlush(user); This is a lengthy process, and we thought it would be a perfect candidate for testing out the .NET 4.0 Parallel libraries. So we wrapped the loop in a: Parallel.ForEach(); After doing this, we start getting "random" Timeout Exceptions from SQL Server, and finally, after leaving it running all night, OutOfMemory unhandled exceptions. I haven't done deep debugging on this yet, but what do you guys think. Is this simply a limitation of SQL Server, or could it be our NHibernate setup, or what? cheers andy

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  • NHibernate, the Parallel Framework, and SQL Server

    - by andy
    hey guys, we have a loop that: 1.Loops over several thousand xml files. Altogether we're parsing millions of "user" nodes. 2.In each iteration we parse a "user" xml, do custom deserialization 3.finally, in each iteration, we send our object to nhibernate for saving. We use: .SaveOrUpdateAndFlush(user); This is a lengthy process, and we thought it would be a perfect candidate for testing out the .NET 4.0 Parallel libraries. So we wrapped the loop in a: Parallel.ForEach(); After doing this, we start getting "random" Timeout Exceptions from SQL Server, and finally, after leaving it running all night, OutOfMemory unhandled exceptions. I haven't done deep debugging on this yet, but what do you guys think. Is this simply a limitation of SQL Server, or could it be our NHibernate setup, or what? cheers andy

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  • Function-Local Static Const variable Initialization semantics.

    - by Hassan Syed
    The questions are in bold, for those that cannot be bothered reading a question in depth. This is a followup to this question. It is to do with the initialization semantics of static variables in functions. Static variables should be initialized once, and their internal state might be altered later - as I (currently) do in the linked question. However, the code in question does not require the feature to change the state of the variable later. Let me clarrify my position, since I don't require the string object's internal state to change. The code is for a trait class for meta programming, and as such would would benifit from a const char * const ptr -- thus Ideally a local cost static const variable is needed. My educated guess is that in this case the string in question will be optimally placed in memory by the link-loader, and that the code is more secure and maps to the intended semantics. This leads to the semantics of such a variable "The C++ Programming language Third Edition -- Stroustrup" does not have anything (that I could find) to say about this matter. All that is said is that the variable is initialized once when the flow of control of the thread first reaches the code. This leads me to ponder if the following code would be sensible, and if not what are the intended semantics ?. #include <iostream> const char * const GetString(const char * x_in) { static const char * const x = x_in; return x; } int main() { const char * const temp = GetString("yahoo"); std::cout << temp << std::endl; const char * const temp2 = GetString("yahoo2"); std::cout << temp2 << std::endl; } The following compiles on GCC and prints "yahoo" twice. Which is what I want -- However it might not be standards compliant (which is why I post this question). It might be more elegant to have two functions, "SetString" and "String" where the latter forwards to the first. If it is standards compliant does someone know of a templates implementation in boost (or elsewhere) ?

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  • Using Parallel Extensions In Web Applications

    - by Greg
    I'd like to hear some opinions as to what role, if any, parallel computing approaches, including the potential use of the parallel extensions (June CTP for example), have a in web applications. What scenarios does this approach fit and/or not fit for? My understanding of how exactly IIS and web browsers thread tasks is fairly limited. I would appreciate some insight on that if someone out there has a good understanding. I'm more curious to know if the way that IIS and web browsers work limits the ROI of creating threaded and/or asynchronous tasks in web applications in general. Thanks in advance.

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  • Mock Assertions on objects inside Parallel ForEach's???

    - by jacko
    Any idea how we can assert a mock object was called when it is being accessed inside Parallel.ForEach via a closure? I assume that because each invocation is on a different thread that Rhino Mocks loses track of the object? Pseudocode: var someStub = MockRepository.GenerateStub() Parallel.Foreach(collectionOfInts, anInt => someStub.DoSomething(anInt)) someStub.AssertWasCalled(s => s.DoSomething, Repeat.Five.Times) This test will return an expectation violation, expecting the stub to be called 5 times but being actually called 0 times. Any ideas how we can tell the lambdas to keep track of the thread-local stub object?

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  • Parallel.For maintain input list order on output list

    - by romeozor
    I'd like some input on keeping the order of a list during heavy-duty operations that I decided to try to do in a parallel manner to see if it boosts performance. (It did!) I came up with a solution, but since this was my first attempt at anything parallel, I'd need someone to slap my hands if I did something very stupid. There's a query that returns a list of card owners, sorted by name, then by date of birth. This needs to be rendered in a table on a web page (ASP.Net WebForms). The original coder decided he would construct the table cell-by-cell (TableCell), add them to rows (TableRow), then each row to the table. So no GridView, allegedly its performance is bad, but the performance was very poor regardless :). The database query returns in no time, the most time is spent on looping through the results and adding table cells etc. I made the following method to maintain the original order of the list: private TableRow[] ComposeRows(List<CardHolder> queryResult) { int queryElementsCount = queryResult.Count(); // array with the query's size var rowArray = new TableRow[queryElementsCount]; Parallel.For(0, queryElementsCount, i => { var row = new TableRow(); var cell = new TableCell(); // various operations, including simple ones such as: cell.Text = queryResult[i].Name; row.Cells.Add(cell); // here I'm adding the current item to it's original index // to maintain order in the output list rowArray[i] = row; }); return rowArray; } So as you can see, because I'm returning a very different type of data (List<CardHolder> -> TableRow[]), I can't just simply omit the ordering from the original query to do it after the operations. Also, I also thought it would be a good idea to Dispose() the objects at the end of each loop, because the query can return a huge list and letting cell and row objects pile up in the heap could impact performance.(?) How badly did I do? Does anyone have a better solution in case mine is flawed?

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  • Parallel.For(): Update variable outside of loop

    - by TSS
    I'm just looking in to the new .NET 4.0 features. With that, I'm attempting a simple calculation using Parallel.For and a normal for(x;x;x) loop. However, I'm getting different results about 50% of the time. long sum = 0; Parallel.For(1, 10000, y => { sum += y; } ); Console.WriteLine(sum.ToString()); sum = 0; for (int y = 1; y < 10000; y++) { sum += y; } Console.WriteLine(sum.ToString()); My guess is that the threads are trying to update "sum" at the same time. Is there an obvious way around it?

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  • Parallel.For(): Different results for simple addition

    - by TSS
    I'm just looking in to the new .NET 4.0 features. With that, I'm attempting a simple calculation using Parallel.For and a normal for(x;x;x) loop. However, I'm getting different results about 50% of the time (no code change). long sum = 0; Parallel.For(1, 10000, y => { sum += y; }); Console.WriteLine(sum.ToString()); sum = 0; for (int y = 1; y < 10000; y++) { sum += y; } Console.WriteLine(sum.ToString()); Surely I'm missing something simple or do not completely understand the concept. My guess is that the threads are trying to update "sum" at the same time. If so, is there an obvious way around it?

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  • Microsoft .NET Web Programming: Web Sites versus Web Applications

    - by SAMIR BHOGAYTA
    In .NET 2.0, Microsoft introduced the Web Site. This was the default way to create a web Project in Visual Studio 2005. In Visual Studio 2008, the Web Application has been restored as the default web Project in Visual Studio/.NET 3.x The Web Site is a file/folder based Project structure. It is designed such that pages are not compiled until they are requested ("on demand"). The advantages to the Web Site are: 1) It is designed to accommodate non-.NET Applications 2) Deployment is as simple as copying files to the target server 3) Any portion of the Web Site can be updated without requiring recompilation of the entire Site. The Web Application is a .dll-based Project structure. ASP.NET pages and supporting files are compiled into assemblies that are then deployed to the target server. Advantages of the Web Application are: 1) Precompiled files do not expose code to an attacker 2) Precompiled files run faster because they are binary data (the Microsoft Intermediate Language, or MSIL) executed by the CLR (Common Language Runtime) 3) References, assemblies, and other project dependencies are built in to the compiled site and automatically managed. They do not need to be manually deployed and/or registered in the Global Assembly Cache: deployment does this for you If you are planning on using automated build and deployment, such as the Team Foundation Server Team Build engine, you will need to have your code in the form of a Web Application. If you have a Web Site, it will not properly compile as a Web Application would. However, all is not lost: it is possible to work around the issue by adding a Web Deployment Project to your Solution and then: a) configuring the Web Deployment Project to precompile your code; and b) configuring your Team Build definition to use the Web Deployment Project as its source for compilation. https://msevents.microsoft.com/cui/WebCastEventDetails.aspx?culture=en-US&EventID=1032380764&CountryCode=US

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  • programming practices starting

    - by Tamim Ad Dari
    I have taken my major as computer science and Engineering and I am really confused at this moment. My first course was about learning C and C++ and I learned the basics of those. Now I am really confused what to do next. Some says I should practice algorithms and do contests in ACM-ICPC for now. Others tell me to start software development. But As I started digging its really a vast topic and there are many aspects of these, like web design, web-development, iOS-development, android... etc many things. And I am really confused about what should I do just now. Any advice for me to start with?

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  • How do you research while pair programming?

    - by traffichazard
    I've recently started at a new job and pairing has helped me become effective there very quickly. I am, however, having a hard time when we must do brief joint research during our workflow, covering API features, code examples, or command options. My team lead urges us to do all research on our pairing station, rather than our individual laptops, and to synchronize our research by verbally negotiating the steps between different web resources. I research, read, and absorb information differently from my pairing partner, and I feel much more productive when I can follow a thread of research to the next web page exactly when I want to, rather than trying to keep exact pace and place with what my partner's reading. We're both smart and fast, but we can't help moving in different ways and instantaneous velocities when we're figuring stuff out. It seems so much easier to poke around individually for a minute until one of us says "I've got it," then get back together and code. When you pair program, how do you handle short research tasks? What works best for you, and how to you keep in sync with your partner?

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  • Dangerous programming

    - by benhowdle89
    Ok, i'm talking pure software/web, i'm not on about code to power Life Support machines or NASA rockets. In terms of software/web development what is the most dangerous single piece of code someone could put into a program (say if they had a grudge against a client/employee) In PHP, the first thing that comes to mind is some sort of file deletion: function EmptyDir($dir) { $handle=opendir($dir); while (($file = readdir($handle))!==false) { echo "$file <br>"; @unlink($dir.'/'.$file); } closedir($handle); } EmptyDir('images'); Or a PHP script that takes a user's sensitive input and posts it to Google sitemap or something? I hope this doesnt get closed off as subjective as there surely must be a ranking order of dangerous code. So i'm asking for the No.1 spot :) DISCLAIMER: I have no grudges against anyone, just curious for the answer!

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  • Defensive Programming Techniques.

    - by Pemdas
    I was attempting to identify an element of software engineering that I think is overlooked, not emphasized or not taught in typical undergraduate course work for CS or SE. What I came up is the concept of defensive programing. I would like to hear the communities options on defensive program and/or specific techniques that you use on a regular basis. Also, I would to know if there are any language specific techniques.

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  • Is the C programming language still used?

    - by Pankaj Upadhyay
    I am a C# programmer, and most of my development is for websites along with a few Windows application. As far as C goes, I haven't used it in a long time, as there was no need to. It came to me as a surprise when one of my friends said that she needs to learn C for testing jobs, while I was helping her learn C#. I figured that someone would only learn C for testing only if there is development done in C. In my knowledge, all the development related to COM and hardware design are also done in C++. Therefore, learning C doesn't make sense if you need to use C++. I also don't believe in historic significance, so why waste time and money in learning C? Is C is still used in any kind of new software development or anything else?

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  • Procedural, Semi-Procedural and Declarative Programming in SQL

    A lot of the time, the key to making SQL databases perform well is to take a break from the keyboard and rethink the way of approaching the problem; and rethinking in terms of a set-based declarative approach. Joe takes a simple discussion abut a problem with a UDF to illustrate the point that ingrained procedural reflexes can often prevent us from seeing simpler set-based techniques.

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