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  • C++ priority queue structure userd ?

    - by John Retallack
    While searching for some functions in C++ STL documentation I read that push and pop for priority queues needs constant time. "Constant (in the priority_queue). Although notice that push_heap operates in logarithmic time." My question is what kind of data structure is used to mantain a priority queue with O(1) for push and pop ?

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  • Getting the System tick count with basic C++?

    - by Donal Rafferty
    I essentially want to reconstruct the getTickCount() windows function so I can use it in basic C++ without any non standard libraries or even the STL. (So it complies with the libraries supplied with the Android NDK) I have looked at clock() localtime time But I'm still unsure whether it is possible to replicate the getTickCount windows function with the time library. Can anyone point me in the right direction as to how to do this or even if its possible?

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  • Favorite C/C++ questions for an interview [closed]

    - by Nullw0rm
    What are your favorite C/C++ interview questions? It may be question or contain question of concepts, some subjects are: Logic, multithreading, algorithms (and performance), STL, templates, inheritence, pointers. This is a useful tool for me, to look at what would be tested on a career-like application.

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  • C++ write to front of file

    - by user231536
    I need to open a file as ofstream and write to the front of the file, while preserving the remaining contents of the file, which will be "moved". Similar to "prepend" a file. Is this possible using the STL or boost ?

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  • Good C++ books regarding Performance?

    - by Leon
    Besides the books everyone knows about, like Meyer's 3 Effective C++/STL books, are there any other really good C++ books specifically aimed towards performance code? Maybe this is for gaming, telecommunications, finance/high frequency etc? When I say performance I mean things where a normal C++ book wouldnt bother advising because the gain in performance isn't worthwhile for 95% of C++ developers. Maybe suggestions like avoiding virtual pointers, going into great depth about inlining etc? A book going into great depth on C++ memory allocation or multithreading performance would obviously be very useful.

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  • What's wrong with cplusplus.com?

    - by Kerrek SB
    This is perhaps not a perfectly suitable forum for this question, but let me give it a shot, at the risk of being moved away. There are several references for the C++ standard library, including the invaluable ISO standard, MSDN, IBM, cppreference, and cplusplus. Personally, when writing C++ I need a reference that has quick random access, short load times and usage examples, and I've been finding cplusplus.com pretty useful. However, I've been hearing negative opinions about that website frequently here on SO, so I would like to get specific: What are the errors, misconceptions or bad pieces of advice given by cplusplus.com? What are the risks of using it to make coding decisions? Let me add this point: I want to be able to answer questions here on SO with accurate quotes of the standard, and thus I would like to post immediately-usable links, and cplusplus.com would have been my choice site were it not for this issue. Update: There have been many great responses, and I have seriously changed my view on cplusplus.com. I'd like to list a few choice results here; feel free to suggest more (and keep posting answers). As of June 29, 2011: Incorrect description of some algorithms (e.g. remove). Information about the behaviour of functions is sometimes incorrect (atoi), fails to mention special cases (strncpy), or omits vital information (iterator invalidation). Examples contain deprecated code (#include style). Inexact terminology is doing a disservice to learners and the general community ("STL", "compiler" vs "toolchain"). Incorrect and misleading description of the typeid keyword.

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  • Is there a measure of code rot?

    - by DarenW
    I'm dealing, again, with a messy C++ application, tons of classes with confusing names, objects have pointers into each other and all over, longwinded Boost and STL data types, etc. (Pause and consider your favorite terror of messy legacy code. We probably have it.) The phrase "code rot" oft comes to mind when I work on this project. Is there a quantitative way to measure code rot? I wouldn't expect anything highly meaningful or scientific, since no other measure of code productivity or quality is so fine. I'm not looking for a mere opposite of measures of code quality, but specifically a measure of how many bad things happened after a series of maintenance software "engineers" have had turns hacking at the code. A general measure applying to any language, or many languages, would be great. If there's no such thing, at least for C++, which is a better than average language for creating messes. Maybe something involving a measure of topology of how objects connect during runtime, a count of chunks of commented out code, how mane files a typical variable's usage is scattered over, I don't know... but surely now, a decade into the 21st Century, someone has attempted to define some sort of rot measure. It would be especially interesting to automate a series of svn checkouts, measure the "rottenosity" of each, and plot the decay over time.

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  • Young C++ student lacking direction

    - by ephaitch
    I was hoping for some direction or guidance regarding my C++ learning experience. I have now read two books, from cover to cover, twice. The first was Ivor Horton's Beginning Visual C++ 2010 and Starting out with C++ Early Objects (7th Edition). At this point and after several months I feel like all I know how to do in C++ is create a basic class, define some methods, use the STL, and read and write info to and from the console buffer (cin/cout). But simple things like saving data to a file, reading from a file, printing, connecting to an FTP site, doing some basic graphic manipulation on the screen (not even DirectX/OpenGL), and so-on I can't do or don't even know where to start. I feel I still haven't learned C++ thoroughly. I think you guys get where I'm going with this. I tried downloading SFML and compiling it in Visual C++ 2010 Professional. After quite a bit of time, I got it, but then I was lost. I followed the tutorials and one didn't work. I kept getting an error regarding a missing symbol and after an hour or so on Google, I couldn't figure it out. Can anyone point me in a direction of where one goes from here? I would imagine others have been at this point sometime during their early days.

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  • Java language book for an experienced programmer?

    - by Andrew
    I am looking for book to get up to speed with (start with) a Java language. I am experienced (more than 15 years) C# and C++ programmer with a bit of Python, so I don't need a book which starts with a programming concepts for a beginner. In fact I think I need a "Java language specification" sort of book. I checked the answers to questions similar to mine and found that there two books which is being recommended most: "Effective Java" and "Sun Certified Java Programmer". After a quick look at the "Effective Java" I realised it should not be a book to start with, it is a good book (I read all books in Effective C++, STL series and liked them but they are more "good practices" books, rather than a book for a beginners) "Sun Certified Java Programmer" looks closer to what I am after - but goes too slow for me. So I did some more search and found these two books: The Java(TM) Language Specification by Gosling himself Java™ Programming Language, The (4th Edition) by Ken Arnold I gather the first one a little bit dated and the second one is the best Java Language Reference books up to date, but I am not sure - as I am not a Java person to make such judgements. After reading the language reference book I will start learning the basic libraries / packages / namespaces (collections, algorithms, IO, etc) and then something about UI architecture. But that will come later. Question: - which Java Language reference book for an experienced programmer you can recomend ? and why? Cheers.

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  • CodePlex Daily Summary for Friday, November 09, 2012

    CodePlex Daily Summary for Friday, November 09, 2012Popular ReleasesPlayer Framework by Microsoft: Player Framework for Windows 8 (v1.0): IMPORTANT: List of breaking changes from preview 7 Ability to move control panel or individual elements outside media player. more info... New Entertainment app theme for out of the box support for Windows 8 Entertainment app guidelines. more info... VSIX reference names shortened. Allows seeing plugin name from "Add Reference" dialog without resizing. FreeWheel SmartXML now supports new "Standard" event callback type. Other minor misc fixes and improvements ADDITIONAL DOWNLOADSSmo...WebSearch.Net: WebSearch.Net 3.1: WebSearch.Net is an open-source research platform that provides uniform data source access, data modeling, feature calculation, data mining, etc. It facilitates the experiments of web search researchers due to its high flexibility and extensibility. The platform can be used or extended by any language compatible for .Net 2 framework, from C# (recommended), VB.Net to C++ and Java. Thanks to the large coverage of knowledge in web search research, it is necessary to model the techniques and main...Umbraco CMS: Umbraco 4.10.0: NugetNuGet BlogRead the release blog post for 4.10.0. Whats newMVC support New request pipeline Many, many bugfixes (see the issue tracker for a complete list) Read the documentation for the MVC bits. Breaking changesWe have done all we can not to break backwards compatibility, but we had to do some minor breaking changes: Removed graphicHeadlineFormat config setting from umbracoSettings.config (an old relic from the 3.x days) U4-690 DynamicNode ChildrenAsList was fixed, altering it'...MySQL Tuner for Windows: 0.3: Welcome to the third beta of MySQL Tuner for Windows! This release fixes bugs in the displaying of numbers, and a crash that occurred due to the program incorrectly closing and disposing of resources, Be warned that there will be bugs in this release, so please do not use on production or critical systems. Do post details of issues found to the issue tracker, and I will endeavour to fix them, when I can. I would love to have your feedback, and if possible your support! Requirements Microso...SharePoint Manager 2013: SharePoint Manager 2013 Release ver 1.0.12.1106: SharePoint Manager 2013 Release (ver: 1.0.12.1106) is now ready for SharePoint 2013. The new version has an expanded view of the SharePoint object model and has been tested on SharePoint 2013 RTM. As a bonus, the new version is also available for SharePoint 2010 as a separate download.GL2DX (OpenGL to DirectX Wrapper Library): GL2DX Release 1: The first release contains all source code for the GL2DX library and source code for the sample project demonstrating how to use the library for a Direct3D / XAML hybrid Windows 8 application.WCF y Net remoting en el famoso ejemplo HOLA MUNDO: Ejemplo: Versión liberadaD3D9Client: D3D9Client R7: New release for Orbiter 2010-P1 - Added horizon/sun angle for night-lights into the configuration file (default 10deg) - Some runway lights related bugs are fixed - Added more configuration options for runway lightsFiskalizacija za developere: FiskalizacijaDev 1.2: Verzija 1.2. je, prije svega, odgovor na novu verziju Tehnicke specifikacije (v1.1.) koja je objavljena prije nekoliko dana. Pored novosti vezanih uz (sitne) izmjene u spomenutoj novoj verziji Tehnicke dokumentacije, projekt smo prošili sa nekim dodatnim feature-ima od kojih je vecina proizašla iz vaših prijedloga - hvala :) Novosti u v1.2. su: - Neusuglašenost zahtjeva (http://fiskalizacija.codeplex.com/workitem/645) - Sample projekt - iznosi se množe sa 100 (http://fiskalizacija.codeplex.c...MFCMAPI: October 2012 Release: Build: 15.0.0.1036 Full release notes at SGriffin's blog. If you just want to run the MFCMAPI or MrMAPI, get the executables. If you want to debug them, get the symbol files and the source. The 64 bit builds will only work on a machine with Outlook 2010 64 bit installed. All other machines should use the 32 bit builds, regardless of the operating system. Facebook BadgeJayData - The cross-platform HTML5 data-management library for JavaScript: JayData 1.2.3: JayData is a unified data access library for JavaScript to CRUD + Query data from different sources like OData, MongoDB, WebSQL, SqLite, HTML5 localStorage, Facebook or YQL. The library can be integrated with Knockout.js or Sencha Touch 2 and can be used on Node.js as well. See it in action in this 6 minutes video Sencha Touch 2 example app using JayData: Netflix browser. What's new in JayData 1.2.3 For detailed release notes check the release notes. TypeScript supportWrite your code in a ...MCEBuddy 2.x: MCEBuddy 2.3.7: Changelog for 2.3.7 (32bit and 64bit) 1. Improved performance of MP4 Fast and M4V Fast Profiles (no deinterlacing, removed --decomb) 2. Improved priority handling 3. Added support for Pausing and Resume conversions 4. Added support for fallback to source directory if network destination directory is unavailable 5. MCEBuddy now installs ShowAnalyzer during installation 6. Added support for long description atom in iTunesFoxyXLS: FoxyXLS Releases: Source code and samplesHTML Renderer: HTML Renderer 1.0.0.0 (3): Major performance improvement (http://theartofdev.wordpress.com/2012/10/25/how-i-optimized-html-renderer-and-fell-in-love-with-vs-profiler/) Minor fixes raised in issue tracker and discussions.Window Manager: Window Manager 1.0: First releaseProDinner - ASP.NET MVC Sample (EF4.4, N-Tier, jQuery): 8: update to ASP.net MVC Awesome 3.0 udpate to EntityFramework 4.4 update to MVC 4 added dinners grid on homepageASP.net MVC Awesome - jQuery Ajax Helpers: 3.0: added Grid helper added XML Documentation added textbox helper added Client Side API for AjaxList removed .SearchButton from AjaxList AjaxForm and Confirm helpers have been merged into the Form helper optimized html output for AjaxDropdown, AjaxList, Autocomplete works on MVC 3 and 4BlogEngine.NET: BlogEngine.NET 2.7: Cheap ASP.NET Hosting - $4.95/Month - Click Here!! Click Here for More Info Cheap ASP.NET Hosting - $4.95/Month - Click Here! If you want to set up and start using BlogEngine.NET right away, you should download the Web project. If you want to extend or modify BlogEngine.NET, you should download the source code. If you are upgrading from a previous version of BlogEngine.NET, please take a look at the Upgrading to BlogEngine.NET 2.7 instructions. If you looking for Web Application Project, ...Launchbar: Launchbar 4.2.2.0: This release is the first step in cleaning up the code and using all the latest features of .NET 4.5 Changes 4.2.2 (2012-11-02) Improved handling of left clicks 4.1.0 (2012-10-17) Removed tray icon Assembly renamed and signed with strong name Note When you upgrade, Launchbar will start with the default settings. You can import your previous settings by following these steps: Run Launchbar and just save the settings without configuring anything Shutdown Launchbar Go to the folder %LOCA...CommonLibrary.NET: CommonLibrary.NET 0.9.8.8: Releases notes for FluentScript located at http://fluentscript.codeplex.com/wikipage?title=Release%20Notes&referringTitle=Documentation Fluentscript - 0.9.8.8 - Final ReleaseApplication: FluentScript Version: 0.9.8.8 Build: 0.9.8.8 Changeset: 77368 ( CommonLibrary.NET ) Release date: November 2nd, 2012 Binaries: CommonLibrary.dll Namespace: ComLib.Lang Project site: http://fluentscript.codeplex.com/ Download: http://commonlibrarynet.codeplex.com/releases/view/90426 Source code: http://common...New Projects.NET Data Export Examples: This project is created to export data in C#,VB.NET from database,listview,command to PDF, Word,Excel,RTF,Html,XML,Access,DBF,SQL Script,SYLK,DIF,CSV,Clipboardb9b18a35-a80a-440c-bb8c-195be0225cfa: b9b18a35-a80a-440c-bb8c-195be0225cfaBudget Monkey: Personal Budgeting and Expense Tracking Application - ASP.Net MVC 4 - LINQ - Sql Server ClassLibrary5: ?0?????ORM ??:http://www.cnblogs.com/wushilonng/archive/2011/11/21/2257657.html ??????????????.CodeTextBox: CodeTextBox is a Windows Forms control for colorizing code while you are typing in the text box.Content Management System: web projectCopperfield: Copperfield is an extensibility framework built around contextual awareness. It is intended to be used in combination with one's DI / IoC framework of choice.Cyfuscator: This project show how create your own obfuscator for application .net, as a protection source codeData Browser: The Data Browser is a Windows 8 application that provides a great way to navigate and explore data (ODATA, RDF, ATOM, RDFa) published on the web. DevTask: Dev Task With MVC 4 and EF5DVB Viewer EPG Update Script: DVB Viewer EPG Update ScriptFcompress: Fcompress est un programme de compression simple, rapide et efficace de texte (mots). Programme conçu pour Eurêmaths, groupe Europole.Fdecompress: Fdecompress sert à décomprimer tout mot ou texte comprimer avec Fcompress.Hiren's Boot CD Program Launcher (Unicode support): Hiren's Boot CD Program Launcher (Unicode support)Image Gallery for WPF: A simple image gallery controlIMDb API: C# Class for grabbing data from the IMDb website.License Migration Live@edu Exchange to Office 365 A2: Only a little help to change the licenses after migration from Live@edu to Office 365MvcMSFootballManager: ASP MVC3 self-trainingNage: .NET Agent-based evolution frameworkOE NIK szakirány féléves: Féléves feladat.Office365 Helper: Office365 Helper is a collection of classes and methods to assist in administering and developing solutions for SharePoint online.Powershell Depo: This a collection of Powershell scripts that are collected and modified from anywhere and everywhere. Feel free to download whatever you need.Proejct13251109: sssProject13271109: sdfgdRemotableViewModel: The RemotableViewModel (RVM) library allows sharing of ViewModels accross process boundaries following the Model-View-ViewModel (MVVM) pattern.ScriptEngine: ScriptEngine for C#, JavaScript, VB. The ScriptEngine enables perform script snippets/files. In addition, the scripts can be cached.Shibboleth IdP Loader for ADFS: A PowerShell script to load Shibboleth federation IdPs as ADFS trusted claims providerSparklings: Game in which you change sparklings abilities using spots of light to help them reach the exit.Stala - Auto-update essentials: C# library and examples for event driven auto-updates without predefined graphical components/windows. Works with MSI packages and installer over web/intranet.STeaL : stealed functionarities from STL: STeaL is a .NET class library implemented with C# and enables you to use STL functionarities. especially, various of IList<T> extensions included.TechQueue: A series of Projects and code which are described in the blog http://techqueue.wordpress.comtesttom11082012git03: fsatesttom11082012tfs02: dsToyunda Phone: A simple searchable list of the songs available at the Karaoke rooms in the Epitanime event ran by students at the school named Epita in Paris.WebSearch.Net: WebSearch.Net is an open-source research platform that provides uniform data source access, data modeling, feature calculation, data mining, etc. Win8Controls: This project contains XAML based calendar control for WinRT / Windows Store Style application.WindowsCommonStorage: windows common storage

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  • Random Complete System Unresponsiveness Running Mathematical Functions

    - by Computer Guru
    I have a program that loads a file (anywhere from 10MB to 5GB) a chunk at a time (ReadFile), and for each chunk performs a set of mathematical operations (basically calculates the hash). After calculating the hash, it stores info about the chunk in an STL map (basically <chunkID, hash>) and then writes the chunk itself to another file (WriteFile). That's all it does. This program will cause certain PCs to choke and die. The mouse begins to stutter, the task manager takes 2 min to show, ctrl+alt+del is unresponsive, running programs are slow.... the works. I've done literally everything I can think of to optimize the program, and have triple-checked all objects. What I've done: Tried different (less intensive) hashing algorithms. Switched all allocations to nedmalloc instead of the default new operator Switched from stl::map to unordered_set, found the performance to still be abysmal, so I switched again to Google's dense_hash_map. Converted all objects to store pointers to objects instead of the objects themselves. Caching all Read and Write operations. Instead of reading a 16k chunk of the file and performing the math on it, I read 4MB into a buffer and read 16k chunks from there instead. Same for all write operations - they are coalesced into 4MB blocks before being written to disk. Run extensive profiling with Visual Studio 2010, AMD Code Analyst, and perfmon. Set the thread priority to THREAD_MODE_BACKGROUND_BEGIN Set the thread priority to THREAD_PRIORITY_IDLE Added a Sleep(100) call after every loop. Even after all this, the application still results in a system-wide hang on certain machines under certain circumstances. Perfmon and Process Explorer show minimal CPU usage (with the sleep), no constant reads/writes from disk, few hard pagefaults (and only ~30k pagefaults in the lifetime of the application on a 5GB input file), little virtual memory (never more than 150MB), no leaked handles, no memory leaks. The machines I've tested it on run Windows XP - Windows 7, x86 and x64 versions included. None have less than 2GB RAM, though the problem is always exacerbated under lower memory conditions. I'm at a loss as to what to do next. I don't know what's causing it - I'm torn between CPU or Memory as the culprit. CPU because without the sleep and under different thread priorities the system performances changes noticeably. Memory because there's a huge difference in how often the issue occurs when using unordered_set vs Google's dense_hash_map. What's really weird? Obviously, the NT kernel design is supposed to prevent this sort of behavior from ever occurring (a user-mode application driving the system to this sort of extreme poor performance!?)..... but when I compile the code and run it on OS X or Linux (it's fairly standard C++ throughout) it performs excellently even on poor machines with little RAM and weaker CPUs. What am I supposed to do next? How do I know what the hell it is that Windows is doing behind the scenes that's killing system performance, when all the indicators are that the application itself isn't doing anything extreme? Any advice would be most welcome.

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  • Are there any real-world cases for C++ without exceptions?

    - by Martin
    In When to use C over C++, and C++ over C? there is a statement wrt. to code size / C++ exceptions: Jerry answers (among other points): (...) it tends to be more difficult to produce truly tiny executables with C++. For really small systems, you're rarely writing a lot of code anyway, and the extra (...) to which I asked why that would be, to which Jerry responded: the main thing is that C++ includes exception handling, which (at least usually) adds some minimum to the executable size. Most compilers will let you disable exception handling, but when you do the result isn't quite C++ anymore. (...) which I do not really doubt on a technical real world level. Therefore I'm interested (purely out of curiosity) to hear from real world examples where a project chose C++ as a language and then chose to disable exceptions. (Not just merely "not use" exceptions in user code, but disable them in the compiler, so that you can't throw or catch exceptions.) Why does a project chose to do so (still using C++ and not C, but no exceptions) - what are/were the (technical) reasons? Addendum: For those wishing to elaborate on their answers, it would be nice to detail how the implications of no-exceptions are handled: STL collections (vector, ...) do not work properly (allocation failure cannot be reported) new can't throw Constructors cannot fail

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  • Learning good OOP design & unlearning some bad habits

    - by Nick
    I have been mostly a C programmer so far in my career with knowledge of C++. I rely on C++ mostly for the convenience STL provides and I hardly ever focus on good design practices. As I have started to look for a new job position, this bad habit of mine has come back to haunt me. During the interviews, I have been asked to design a problem (like chess, or some other scenario) using OOP and I doing really badly at that (I came to know this through feedback from one interview). I tried to google stuff and came up with so many opinions and related books that I don't know where to begin. I need a good through introduction to OOP design with which I can learn practical design, not just theory. Can you point me to any book which meets my requirements ? I prefer C++, but any other language is fine as long as I can pick-up good practices. Also, I know that books can only go so far. I would also appreciate any good practice project ideas that helped you learn and improve your OOP concepts. Thanks.

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  • What's wrong with cplusplus.com?

    - by Kerrek SB
    This is perhaps not a perfectly suitable forum for this question, but let me give it a shot, at the risk of being moved away. There are several references for the C++ standard library, including the invaluable ISO standard, MSDN, IBM, cppreference, and cplusplus. Personally, when writing C++ I need a reference that has quick random access, short load times and usage examples, and I've been finding cplusplus.com pretty useful. However, I've been hearing negative opinions about that website frequently here on SO, so I would like to get specific: What are the errors, misconceptions or bad pieces of advice given by cplusplus.com? What are the risks of using it to make coding decisions? Let me add this point: I want to be able to answer questions here on SO with accurate quotes of the standard, and thus I would like to post immediately-usable links, and cplusplus.com would have been my choice site were it not for this issue. Update: There have been many great responses, and I have seriously changed my view on cplusplus.com. I'd like to list a few choice results here; feel free to suggest more (and keep posting answers). As of June 29, 2011: Incorrect description of some algorithms (e.g. remove). Information about the behaviour of functions is sometimes incorrect (atoi), fails to mention special cases (strncpy), or omits vital information (iterator invalidation). Examples contain deprecated code (#include style). Inexact terminology is doing a disservice to learners and the general community ("STL", "compiler" vs "toolchain"). Incorrect and misleading description of the typeid keyword.

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  • What to learn after standard C++?

    - by Luca Cerone
    I switched to C++ a few months ago, learning its syntax, the main features of the STL and what you can usually find in a "learn C++" manual. Now I would like to go further. What would be your recommendations? I would like to know what to learn next (not only about the language, but also debugging, frameworks etc. etc.) I know probably the answer depends on the specific needs of each user, so here is a list of mine: Cross Platform development Developing GUI for my programs Develop extendible software, allowing the use of plugins Use of scientific libraries Interact with databases (mainly MySQL) Having server/client functionalities (I'd like users of my programs to interact through internet.. as you might have guessed I am not a programmer by training so I might have used the wrong terms.. if so I apologize for that). Of course I know it takes time, but I would like to have a good list of references and resources to start (both books and websites are ok). Thanks a lot for your help!

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  • Effective optimization strategies on modern C++ compilers

    - by user168715
    I'm working on scientific code that is very performance-critical. An initial version of the code has been written and tested, and now, with profiler in hand, it's time to start shaving cycles from the hot spots. It's well-known that some optimizations, e.g. loop unrolling, are handled these days much more effectively by the compiler than by a programmer meddling by hand. Which techniques are still worthwhile? Obviously, I'll run everything I try through a profiler, but if there's conventional wisdom as to what tends to work and what doesn't, it would save me significant time. I know that optimization is very compiler- and architecture- dependent. I'm using Intel's C++ compiler targeting the Core 2 Duo, but I'm also interested in what works well for gcc, or for "any modern compiler." Here are some concrete ideas I'm considering: Is there any benefit to replacing STL containers/algorithms with hand-rolled ones? In particular, my program includes a very large priority queue (currently a std::priority_queue) whose manipulation is taking a lot of total time. Is this something worth looking into, or is the STL implementation already likely the fastest possible? Along similar lines, for std::vectors whose needed sizes are unknown but have a reasonably small upper bound, is it profitable to replace them with statically-allocated arrays? I've found that dynamic memory allocation is often a severe bottleneck, and that eliminating it can lead to significant speedups. As a consequence I'm interesting in the performance tradeoffs of returning large temporary data structures by value vs. returning by pointer vs. passing the result in by reference. Is there a way to reliably determine whether or not the compiler will use RVO for a given method (assuming the caller doesn't need to modify the result, of course)? How cache-aware do compilers tend to be? For example, is it worth looking into reordering nested loops? Given the scientific nature of the program, floating-point numbers are used everywhere. A significant bottleneck in my code used to be conversions from floating point to integers: the compiler would emit code to save the current rounding mode, change it, perform the conversion, then restore the old rounding mode --- even though nothing in the program ever changed the rounding mode! Disabling this behavior significantly sped up my code. Are there any similar floating-point-related gotchas I should be aware of? One consequence of C++ being compiled and linked separately is that the compiler is unable to do what would seem to be very simple optimizations, such as move method calls like strlen() out of the termination conditions of loop. Are there any optimization like this one that I should look out for because they can't be done by the compiler and must be done by hand? On the flip side, are there any techniques I should avoid because they are likely to interfere with the compiler's ability to automatically optimize code? Lastly, to nip certain kinds of answers in the bud: I understand that optimization has a cost in terms of complexity, reliability, and maintainability. For this particular application, increased performance is worth these costs. I understand that the best optimizations are often to improve the high-level algorithms, and this has already been done.

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  • How to persuade C fanatics to work on my C++ open source project?

    - by paperjam
    I am launching an open-source project into a space where a lot of the development is still done Linux-kernel-style, i.e. C-language with a low-level mindset. There are multiple benefits to C++ in our space but I fear those used to working in C will be scared off. How can I make the case for the benefits of C++? Specifically, the following C++ attributes are very valuable: concept of objects and reference-counting pointers - really don't want to have to malloc(sizeof(X)) or memcpy() structs templates for specialising whole bodies of code with specific performance optimizations and for avoiding duplication of code. template metaprogramming related to the above syntactic sweetness available (e.g. operator overloading, to be used in very small doses) STL Boost libraries Many of the knee-jerk negative reactions to C++ are illfounded. Performance does not suffer: modern compilers can flatten dozens of call stack levels and avoid bloat through wide use of template specializations. Granted, when using metaprogramming and building multiple specializations of a large call tree, compile time is slower but there are ways to mitigate this. How can I sell C++?

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  • CodePlex Daily Summary for Friday, January 07, 2011

    CodePlex Daily Summary for Friday, January 07, 2011Popular ReleasesAutoLoL: AutoLoL v1.5.2: Implemented the Auto Updater Fix: Your settings will no longer be cleared with new releases of AutoLoL The mastery Editor and Browser now have their own tabs instead of nested tabs The Browser tab will only show the masteries matching ALL filters instead of just one Added a 'Browse' button in the Mastery Editor tab to open the Masteries Directory The Browser tab now shows a message when there are no mastery files in the Masteries Directory Fix: Fixed the Save As dialog again, for ...Ionics Isapi Rewrite Filter: 2.1 latest stable: V2.1 is stable, and is in maintenance mode. This is v2.1.1.25. It is a bug-fix release. There are no new features. 28629 29172 28722 27626 28074 29164 27659 27900 many documentation updates and fixes proper x64 build environment. This release includes x64 binaries in zip form, but no x64 MSI file. You'll have to manually install x64 servers, following the instructions in the documentation.StyleCop for ReSharper: StyleCop for ReSharper 5.1.14980.000: A considerable amount of work has gone into this release: Huge focus on performance around the violation scanning subsystem: - caching added to reduce IO operations around reading and merging of settings files - caching added to reduce creation of expensive objects Users should notice condsiderable perf boost and a decrease in memory usage. Bug Fixes: - StyleCop's new ObjectBasedEnvironment object does not resolve the StyleCop installation path, thus it does not return the correct path ...VivoSocial: VivoSocial 7.4.1: New release with bug fixes and updates for performance.SSH.NET Library: 2011.1.6: Fixes CommandTimeout default value is fixed to infinite. Port Forwarding feature improvements Memory leaks fixes New Features Add ErrorOccurred event to handle errors that occurred on different thread New and improve SFTP features SftpFile now has more attributes and some operations Most standard operations now available Allow specify encoding for command execution KeyboardInteractiveConnectionInfo class added for "keyboard-interactive" authentication. Add ability to specify bo....NET Extensions - Extension Methods Library for C# and VB.NET: Release 2011.03: Added lot's of new extensions and new projects for MVC and Entity Framework. object.FindTypeByRecursion Int32.InRange String.RemoveAllSpecialCharacters String.IsEmptyOrWhiteSpace String.IsNotEmptyOrWhiteSpace String.IfEmptyOrWhiteSpace String.ToUpperFirstLetter String.GetBytes String.ToTitleCase String.ToPlural DateTime.GetDaysInYear DateTime.GetPeriodOfDay IEnumberable.RemoveAll IEnumberable.Distinct ICollection.RemoveAll IList.Join IList.Match IList.Cast Array.IsNullOrEmpty Array.W...VidCoder: 0.8.0: Added x64 version. Made the audio output preview more detailed and accurate. If the chosen encoder or mixdown is incompatible with the source, the fallback that will be used is displayed. Added "Auto" to the audio mixdown choices. Reworked non-anamorphic size calculation to work better with non-standard pixel aspect ratios and cropping. Reworked Custom anamorphic to be more intuitive and allow display width to be set automatically (Thanks, Statick). Allowing higher bitrates for 6-ch....NET Voice Recorder: Auto-Tune Release: This is the source code and binaries to accompany the article on the Coding 4 Fun website. It is the Auto Tuner release of the .NET Voice Recorder application.BloodSim: BloodSim - 1.3.2.0: - Simulation Log is now automatically disabled and hidden when running 10 or more iterations - Hit and Expertise are now entered by Rating, and include option for a Racial Expertise bonus - Added option for boss to use a periodic magic ability (Dragon Breath) - Added option for boss to periodically Enrage, gaining a Damage/Attack Speed buffASP.NET MVC CMS ( Using CommonLibrary.NET ): CommonLibrary.NET CMS 0.9.5 Alpha: CommonLibrary CMSA simple yet powerful CMS system in ASP.NET MVC 2 using C# 4.0. ActiveRecord based components for Blogs, Widgets, Pages, Parts, Events, Feedback, BlogRolls, Links Includes several widgets ( tag cloud, archives, recent, user cloud, links twitter, blog roll and more ) Built using the http://commonlibrarynet.codeplex.com framework. ( Uses TDD, DDD, Models/Entities, Code Generation ) Can run w/ In-Memory Repositories or Sql Server Database See Documentation tab for Ins...AllNewsManager.NET: AllNewsManager.NET 1.2.1: AllNewsManager.NET 1.2.1 It is a minor update from version 1.2EnhSim: EnhSim 2.2.9 BETA: 2.2.9 BETAThis release supports WoW patch 4.03a at level 85 To use this release, you must have the Microsoft Visual C++ 2010 Redistributable Package installed. This can be downloaded from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=A7B7A05E-6DE6-4D3A-A423-37BF0912DB84 To use the GUI you must have the .NET 4.0 Framework installed. This can be downloaded from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=9cfb2d51-5ff4-4491-b0e5-b386f32c0992 - Added in the Gobl...xUnit.net - Unit Testing for .NET: xUnit.net 1.7 Beta: xUnit.net release 1.7 betaBuild #1533 Important notes for Resharper users: Resharper support has been moved to the xUnit.net Contrib project. Important note for TestDriven.net users: If you are having issues running xUnit.net tests in TestDriven.net, especially on 64-bit Windows, we strongly recommend you upgrade to TD.NET version 3.0 or later. This release adds the following new features: Added support for ASP.NET MVC 3 Added Assert.Equal(double expected, double actual, int precision)...Json.NET: Json.NET 4.0 Release 1: New feature - Added Windows Phone 7 project New feature - Added dynamic support to LINQ to JSON New feature - Added dynamic support to serializer New feature - Added INotifyCollectionChanged to JContainer in .NET 4 build New feature - Added ReadAsDateTimeOffset to JsonReader New feature - Added ReadAsDecimal to JsonReader New feature - Added covariance to IJEnumerable type parameter New feature - Added XmlSerializer style Specified property support New feature - Added ...DbDocument: DbDoc Initial Version: DbDoc Initial versionASP .NET MVC CMS (Content Management System): Atomic CMS 2.1.2: Atomic CMS 2.1.2 release notes Atomic CMS installation guide N2 CMS: 2.1: N2 is a lightweight CMS framework for ASP.NET. It helps you build great web sites that anyone can update. Major Changes Support for auto-implemented properties ({get;set;}, based on contribution by And Poulsen) All-round improvements and bugfixes File manager improvements (multiple file upload, resize images to fit) New image gallery Infinite scroll paging on news Content templates First time with N2? Try the demo site Download one of the template packs (above) and open the proj...Mobile Device Detection and Redirection: 0.1.11.10: IMPORTANT CHANGESThis release changes the way some WURFL capabilities and attributes are exposed to .NET developers. If you cast MobileCapabilities to return some values then please read the Release Note before implementing this release. The following code snippet can be used to access any WURFL capability. For instance, if the device is a tablet: string capability = Request.Browser["is_tablet"]; SummaryNew attributes have been added to the redirect section: originalUrlAsQueryString If se...Wii Backup Fusion: Wii Backup Fusion 1.0: - Norwegian translation - French translation - German translation - WBFS dump for analysis - Scalable full HQ cover - Support for log file - Load game images improved - Support for image splitting - Diff for images after transfer - Support for scrubbing modes - Search functionality for log - Recurse depth for Files/Load - Show progress while downloading game cover - Supports more databases for cover download - Game cover loading routines improvedBlogEngine.NET: BlogEngine.NET 2.0: Get DotNetBlogEngine for 3 Months Free! Click Here for More Info 3 Months FREE – BlogEngine.NET Hosting – Click Here! If you want to set up and start using BlogEngine.NET right away, you should download the Web project. If you want to extend or modify BlogEngine.NET, you should download the source code. If you are upgrading from a previous version of BlogEngine.NET, please take a look at the Upgrading to BlogEngine.NET 2.0 instructions. To get started, be sure to check out our installatio...New Projects9192631770: This project is created for learning .net 3.5 personally. However it may not suffice for anyone to give a start point. (9192631770) is equivalent to 1 sec in atomic clock.AGS: AGSAll-In-One Code Framework Prerelease: All-In-One Code Framework PrereleaseAwait Events with "yield": This is a library that allows you to stop running the code wherever you want in order to await an event using the functionality of "yield" sentence. It's useful when you want to await asynchronous events or when you have to deal with many events in a sequential way.Battle.net SDK: This is a SDK that retrieves it's information from the Battle.Net community site. At the moment blizzard only supports this for World of Warcraft, so that's what our main aim is at the momeen.t C++ Hash Container Benchmark: C++ Hash Container Benchmark for STL map, C++0x unordered map, Boost unordered map, ATL map and ATL hash map for STL wide string and ATL CString.Colour Lovers .NET: A .NET library for the Colour Lovers API.DatingGame: Course to teach high-school aged girls basic T-SQL using a fun scenario - querying to find the hottest boys! Used at Microsoft DigiGirlz and TKP events. Included DDL script, CSV for bcp with data, PPTX, T-SQL Cheat Sheet and teaching tips. Enjoy!do-Dots open .NET SDK: The do-Dots open SDK brings developers a full set of classes that allow to build applications based on do-Dots, a framework for M2M communication. It's developed in C#. EFMVC - ASP.NET MVC 3 and EF Code First: Demo web app using ASP.NET MVC 3 and EF Code FirstGS1: D is a 2D game demo written in C++ and using an API : HAPI for the graphic part and the audio part. All the xml files are handled with tinyXML. It is a vertical scrolling shoot'em up where the player controls a dragon flying in Central Park.GS2: In Zombies, you are a wizard, the most powerful wizard in the world, and two days ago, the Devil forces began to attack our world. The only person capable of stopping them is you, this is why the Devil himself came to you and took your powers. You're now alone, without any weaponIPProvider: DFGiwtfly: ????iwtfly26050: iwtfly2Knowledge Exchange .Net: This is my learning experience with creating an enterprise scale .NET application with tools such as Tortoise SVN, NANT, and Linq to SQLLinqPad Data Context Driver for SharePoint: The SharePoint Data Context Driver for LinqPad makes it easer for SharePoint 2010 Developers to develop, maintain and just play around with Linq To SharePoint statements via LinqPad. It is developed in C# and enables SharePoint 2010 Support to LinqPad.MaxLeafWebSiteK3: MaxLeafWebSiteK3Open ASP.NET CMS: Open ASP.NET 3.5 CMS Plug 'N Play Settings Manager: Plug 'N Play Settings Manager will be an application to configure settings on a windows computer by waiting for a usb thumbstick with a configuration file to be inserted, the application would then read and apply those settings. The early focus will be applying network settings.project windy: Windy - enhanced window manager. windy does window management a breeze. It started as a windows alternative to divvy, but now it has evolved with into its own. Thanks to the generous feedback from you folks. whats different from divvy? - first - its free. - has divvy likeRiaMVVM : MVVM Friendly WCF Ria Services: Simple, light-weight, MVVM friendly access to WCF Ria Services. Written in C# for use with Silverlight 4.SharePoint Designer 2007 Policy: Enable or Disable SharePoint Designer 2007 per site web application and per site colleciton. Spruckus - SharePoint ReUsable Content Keystamp Usage Search: Adds a keystamp to all html type items in the SharePoint Reusable Content list and adds a context item to the reusable content list that will find usages of that reusable content in your site using search.Student Insiders: Student InsidersTea: Tea Web Operator SystemVegas.NET: Projeto teste de TransportadoraXNA 4 Game state management system: XNA 4 Game State Management??????: aa

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  • Extracting, then passing raw data into another class - How to avoid copying twice while maintaining

    - by Kache4
    Consider a class Book with a stl container of class Page. each Page holds a screenshot, like page10.jpg in raw vector<char> form. A Book is opened with a path to a zip, rar, or directory containing these screenshots, and uses respective methods of extracting the raw data, like ifstream inFile.read(buffer, size);, or unzReadCurrentFile(zipFile, buffer, size). It then calls the Page(const char* stream, int filesize) constructor. Right now, it's clear that the raw data is being copied twice. Once to extract to Book's local buffer and a second time in the Page ctor to the Page::vector<char>. Is there a way to maintain encapsulation while getting rid of the middleman buffer?

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  • Storing callbacks in a dictionary (Objective C for the iPhone)

    - by Casebash
    I am trying to store callbacks in a dictionary. I can't use blocks as the iPhone doesn't support this (unless you use plblocks). I tried using functions, but apparently NSMutableDictionary doesn't allow these pointers (wants an id) I tried using class methods, but I couldn't find a way to obtain a pointer to these I could try using functions with the c++ stl hashmap (if it is supported in Objective C++), but apparently this can slow compilation times. I could try storing both a class and a selector, but that seems rather messy. What would be the best way to do this?

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