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  • Do you ever feel confident in your skills?

    - by Gary Willoughby
    As a self taught developer i always find myself questioning my skill and knowledge and always feel like i am falling behind in using new technology. Over a period of nearly 9 years i've studied most mainstream languages (especially C based ones), used lots of different OSes, read and absorbed many books and even written one myself. But i still feel i'm usless! Do professional developers ever get to the stage where they feel confident that they know what they are doing and are confident when submitting solutions/code? When do you know you're good enough?

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  • How to let users edit list<T> content?

    - by iTayb
    I'm making an aspx page that can edit books. A book is an complex class with lots of properties. I've made an edit page for most of them, however I'm having trouble with showing edit options for my Sellers Proprety. It is an list<Seller> object. Seller is as follows: public class Seller { private string sellerName; private double price; } How can I print a list to the screen, and let the clinet edit it, then load it back to the object? Thank you very much.

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  • C# WinForms MultiThreading in Loop

    - by Goober
    Scenario I have a background worker in my application that runs off and does a bunch of processing. I specifically used this implementation so as to keep my User Interface fluid and prevent it from freezing up. I want to keep the background worker, but inside that thread, spawn off ONLY 3 MORE threads - making them share the processing (currently the worker thread just loops through and processes each asset one-by-one. However I would like to speed this up but using only a limited number of threads. Question Given the code below, how can I get the loop to choose a thread that is free, and then essentially wait if there isn't one free before it continues. CODE foreach (KeyValuePair<int, LiveAsset> kvp in laToHaganise) { Haganise h = new Haganise(kvp.Value, busDate, inputMktSet, outputMktSet, prodType, noOfAssets, bulkSaving); h.DoWork(); } Thoughts I'm guessing that I would have to start off by creating 3 new threads, but my concern is that if I'm instantiating a new Haganise object each time - how can I pass the correct "h" object to the correct thread..... Thread firstThread = new Thread(new ThreadStart(h.DoWork)); Thread secondThread =new Thread(new ThreadStart(h.DoWork)); Thread thirdThread = new Thread(new ThreadStart(h.DoWork)); Help greatly appreciated.

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  • GA written in Java

    - by EnderMB
    I am attempting to write a Genetic Algorithm based on techniques I had picked up from the book "AI Techniques for Game Programmers" that uses a binary encoding and fitness proportionate selection (also known as roulette wheel selection) on the genes of the population that are randomly generated within the program in a two-dimensional array. I recently came across a piece of pseudocode and have tried to implement it, but have come across some problems with the specifics of what I need to be doing. I've checked a number of books and some open-source code and am still struggling to progress. I understand that I have to get the sum of the total fitness of the population, pick a random number between the sum and zero, then if the number is greater than the parents to overwrite it, but I am struggling with the implementation of these ideas. Any help in the implementation of these ideas would be very much appreciated as my Java is rusty.

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  • How to choose light version of database system

    - by adopilot
    I am starting one POS (Point of sale) project. Targeting system is going to be written in C# .NET 2 WinForms and as main database server We are going to use MS-SQL Server. As we have a lot of POS devices in chain for one store I will love to have backend local data base system on each POS device. Scenario are following: When main server goes down!! POS application should continue working "off-line" with local database, until connection to main server come up again. Now I am in dilemma which local database is going to be most adoptable for me. Here is some notes for helping me point me in right direction: To be Light "My POS devices art usually old and suffering with performances" To be Free "I have a lot of devices and I do not wont additional cost beside main SQL serer" One day Ill love to try all that port on Mono and Linux OS. Here is what I've researched so far: Simple XML "Light but I am afraid of performance, My main table of items is average of 10K records" SQL-Express "I am afraid that my POS devices is poor with hardware for SQLExpress, and also hard to install on each device and configure" Less known Advantage Database Server have free distribution of offline ADT system. DBF with extended Library,"Respect for good old DBFs but that era is behind Me with clipper and DBFs" MS Access Sqlite "Mostly like for now, but I am afraid how it is going to pair with MS SQL do they have same Data types". I know that in this SO is a lot of subjective data, but at least can someone recommended some others lite database system, or things that I shod most take attention before I choice database.

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  • A standard set of questions to ask an interviewer?

    - by Rob Wells
    We have had many questions for interviewers to ask interviewees. But none addressing information flow in the other direction, interviewee to interviewer. Just an indirect question about "deal breakers" and one about "finding dream jobs". What I'm after is when you're interviewing at a company do you have a set of questions that you like to ask to help get a feel for the company and the work environment? I have a series of questions that I like to ask that range from the development environment to testing techniques to how the team get on together. Anything else you'd like to ask? Edit: I moved my original list of interviewer questions to my answer below. I've also gone through the other answers and added the ones thought were useful in to that answer. The answer is community wiki so feel free to add anything useful. N.B. This is my first cut of categories. Feel free to modify/add/etc. the categories. Or to recategorise the questions themselves.

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  • How to retrieve the value from Select html element using JS prototype in php?

    - by user309381
    <script type="text/javascript" src="prototype.js"></script> <script> function reload(form){ var val = $("seltab");alert(val); }</script> echo "<form method = post name = f1 action = '' >"; echo "<select id = seltab onchange = 'reload(this.form)'>"; $querysel = "SELECT title_id,author FROM authors NATURAL JOIN books"; $result1 = mysql_query($querysel) ; while($rowID = mysql_fetch_assoc($result1)) { $TitleID = $rowID['title_id']; $author = $rowID['author']; print "<option value =$TitleID>$author\n"; print "</option>"; } print "</select>";

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  • Django Database design -- Is this a good stragety for overriding defaults

    - by rh0dium
    Hi SO's I have a question on good database design practices and I would like to leverage you guys for pointers. The project started out simple. Hey we have a bunch of questions we want answered for every project (no problem) Which turned into... Hey we have so many questions can we group them into sections (yup we can do that) Which lead into.. Can we weight these questions and I don't really want some of these questions for my project (Yes but we are getting difficult) And then I'm thinking they will want to have each section have it's own weight.. Requirements So there's the requirements - For n number of project Allow a admin member the ability select the questions for a project Allow the admin member to re-weigh or use the default weights for the questions Allow the admin member to re-weight the sections Allow team members to answer the questions. So here is what I came up with. Please feel free to comment and provide better examples models.py from django.db import models from django.contrib.sites.models import Site from django.conf import settings class Section(models.Model): """ This describes the various sections for a checklist: """ name = models.CharField(max_length=64) description = models.TextField() class Question(models.Model): """ This simply provides a simple way to list out the questions. """ question = models.CharField(max_length=255) answer_type = models.CharField(max_length=16) description = models.TextField() section = models.ForeignKey(Section) class ProjectQuestion(models.Model): """ These are the questions relevant to the project """ question = models.ForeignKey(Question) answer = models.CharField(max_length=255) required = models.BooleanField(default=True) weight = models.FloatField(default = XXX) class Project(models.Model): """ Here is where we want to gather our questions """ questions = models.ManyToManyField(ProjectQuestion) Immediate questions: - When I start a project - any ideas on how to "pre-populate" the questions (and ultimately the weights) for the project? - Is there a generally accepted method for doing this process that I am missing? Basically the idea that you refer to the questions overide your own default weight, and store the answer? - It appears that a good chuck of the work will be done in the views and that a lot of checking will need to occur there? Is that OK? Again - feel free to give me better strategies!! Thanks

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  • Core Data table record count

    - by user339633
    I have an entity called Person and it has a relationship called participatingGames, to another entity called GameParticipant. I (apparently) can retrieve the number of matches in the GameParticipant entity using this simple code in the Person object I created from the entity in the model: [self.participatingGames count]; However, I'd just like to retrieve the number of Person records and one might guess the syntax for this is just as simple. I have lots of books including those by Jeff LaMarche, but those sources and what I find around here make me wonder if I need to set up a fetchedResultsController just to know the count of some entity. My background is in SQL, so of course it seems odd that what would take 15 seconds to code in any other environment seems like such a well-guarded secret in Core Data. I'm using iPhone SDK 3.1.4 under OSX 10.5.8 Suggestions?

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  • Lock Question - When is an Update (U) lock issued?

    - by Randy Minder
    We are trying to resolve a deadlock problem. The transaction that is getting rolled back is attempting to issue an Update (U) lock on a resource that another transaction has an Exclusive (X) lock on. According to Books Online (http://msdn.microsoft.com/en-us/library/ms175519.aspx), an Update lock is supposed to prevent deadlocks, not cause them. So, my question is, why/when is an Update lock applied to a resource? We're a little confused about this because the resource that is attempting to have the Update lock applied to will not be updated by the process that is having the transaction rolled back. Thanks for your help on this. Randy

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  • lambda traits inconsistency across C++0x compilers

    - by Sumant
    I observed some inconsistency between two compilers (g++ 4.5, VS2010 RC) in the way they match lambdas with partial specializations of class templates. I was trying to implement something like boost::function_types for lambdas to extract type traits. Check this for more details. In g++ 4.5, the type of the operator() of a lambda appears to be like that of a free standing function (R (*)(...)) whereas in VS2010 RC, it appears to be like that of a member function (R (C::*)(...)). So the question is are compiler writers free to interpret any way they want? If not, which compiler is correct? See the details below. template <typename T> struct function_traits : function_traits<decltype(&T::operator())> { // This generic template is instantiated on both the compilers as expected. }; template <typename R, typename C> struct function_traits<R (C::*)() const> { // inherits from this one on VS2010 RC typedef R result_type; }; template <typename R> struct function_traits<R (*)()> { // // inherits from this one g++ 4.5 typedef R result_type; }; int main(void) { auto lambda = []{}; function_traits<decltype(lambda)>::result_type *r; // void * } This program compiles on both g++ 4.5 and VS2010 but the function_traits that are instantiated are different as noted in the code.

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  • Delphi: Problems with TList of Frames

    - by Dan Kelly
    I'm having a problem with an interface that consists of a number of frames (normally 25) within a TScrollBox. There are 2 problems, and I am hoping that one is a consequence of the other... Background: When the application starts up, I create 25 frames, each containing approx. 20 controls, which are then populated with the default information. The user can then click on a control to limit the search to a subset of information at which point I free and recreate my frames (as the search may return < 25 records) The problem: If I quit the application after the initial search then it takes approx. 5 seconds to return to Delphi. After the 2nd search (and dispose / recreate of frames) it takes approx. 20 seconds) Whilst I could rewrite the application to only create the frames once, I would like to understand what is going on. Here is my create routine: procedure TMF.CreateFrame(i: Integer; var FrameBottom: Integer); var NewFrame: TSF; begin NewFrame := TSF.Create(Self); NewFrame.Name := 'SF' + IntToStr(i); if i = 0 then NewSF.Top := 8 else NewSF.Top := FrameBottom + 8; FrameBottom := NewFrame.Top + NewFrame.Height; NewFrame.Parent := ScrollBox1; FrameList.Add(NewFrame); end; And here is my delete routine: procedure TMF.ClearFrames; var i: Integer; SF: TSF; begin for i := 0 to MF.FrameList.Count -1 do begin SF := FrameList[i]; SF.Free; end; FrameList.Clear; end; What am I missing?

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  • Overcoming C limitations for large projects

    - by Francisco Garcia
    One aspect where C shows its age is the encapsulation of code. Many modern languages has classes, namespaces, packages... a much more convenient to organize code than just a simple "include". Since C is still the main language for many huge projects. How do you to overcome its limitations? I suppose that one main factor should be lots of discipline. I would like to know what you do to handle large quantity of C code, which authors or books you can recommend.

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  • WPF/.NET data access models - resource recommendations

    - by jasonk
    We're in the early design/prep phases of transferring/updating a rather large "legacy" 3 tier client-server app to a new version. We’re looking at doing WPF over Winforms as it appears to be the direction Microsoft is pushing development of the future and we’d like the maximize the life cycle/span of the apps. That said during the rewrite we’d like to make as many changes to our data access/presentation model to improve performance as much as possible up front as many. I’ve been doing some research along that vein but the vast majority of the resources I've found that discuss WPF focus only simple data tracking apps or focus on the very basics UI design/controls. The few items that even discuss data presentation are fairly elementary in depth. Are there any books/articles/recommended reading/other resources recommended for development related to large enterprise level business apps? Any “gotchas” that should/could be avoided? General advice to minimize the time underwater

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  • Resources for TDD aimed at Python Web Development

    - by Null Route
    I am a hacker not and not a full-time programmer but am looking to start my own full application development experiment. I apologize if I am missing something easy here. I am looking for recommendations for books, articles, sites, etc for learning more about test driven development specifically compatible with or aimed at Python web application programming. I understand that Python has built-in tools to assist. What would be the best way to learn about these outside of RTFM? I have searched on StackOverflow and found the Kent Beck's and David Astels book on the subject. I have also bookmarked the Wikipedia article as it has many of these types of resources. Are there any particular ones you would recommend for this language/application?

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  • Great computer-science speeches

    - by sub
    I've looked into some questions here where the "best" programming books are listed and then thought why there isn't a question concerning speeches yet. I think that speeches or presentations from developers or even creators of programming languages which were or are heavily used at some point are particulary interesting. One of my favorite speeches was recommended to me by someone here on SO: The future of C# I also like Guido van Rossum's speeches but he sometimes seems pretty nervous. Another in my opinion good presentation would be the Google tech talk about Go. Which (recorded) programming presentations/speeches are worth watching? edit: Made this a community wiki as the answer would probably be a pretty long list.

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  • Valgrind 'noise', what does it mean?

    - by Chris Huang-Leaver
    When I used valgrind to help debug an app I was working on I notice a huge about of noise which seems to be complaining about standard libraries. As a test I did this; echo 'int main() {return 0;}' | gcc -x c -o test - Then I did this; valgrind ./test ==1096== Use of uninitialised value of size 8 ==1096== at 0x400A202: _dl_new_object (in /lib64/ld-2.10.1.so) ==1096== by 0x400607F: _dl_map_object_from_fd (in /lib64/ld-2.10.1.so) ==1096== by 0x4007A2C: _dl_map_object (in /lib64/ld-2.10.1.so) ==1096== by 0x400199A: map_doit (in /lib64/ld-2.10.1.so) ==1096== by 0x400D495: _dl_catch_error (in /lib64/ld-2.10.1.so) ==1096== by 0x400189E: do_preload (in /lib64/ld-2.10.1.so) ==1096== by 0x4003CCD: dl_main (in /lib64/ld-2.10.1.so) ==1096== by 0x401404B: _dl_sysdep_start (in /lib64/ld-2.10.1.so) ==1096== by 0x4001471: _dl_start (in /lib64/ld-2.10.1.so) ==1096== by 0x4000BA7: (within /lib64/ld-2.10.1.so) * large block of similar snipped * ==1096== Use of uninitialised value of size 8 ==1096== at 0x4F35FDD: (within /lib64/libc-2.10.1.so) ==1096== by 0x4F35B11: (within /lib64/libc-2.10.1.so) ==1096== by 0x4A1E61C: _vgnU_freeres (vg_preloaded.c:60) ==1096== by 0x4E5F2E4: __run_exit_handlers (in /lib64/libc-2.10.1.so) ==1096== by 0x4E5F354: exit (in /lib64/libc-2.10.1.so) ==1096== by 0x4E48A2C: (below main) (in /lib64/libc-2.10.1.so) ==1096== ==1096== ERROR SUMMARY: 3819 errors from 298 contexts (suppressed: 876 from 4) ==1096== malloc/free: in use at exit: 0 bytes in 0 blocks. ==1096== malloc/free: 0 allocs, 0 frees, 0 bytes allocated. ==1096== For counts of detected errors, rerun with: -v ==1096== Use --track-origins=yes to see where uninitialised values come from ==1096== All heap blocks were freed -- no leaks are possible. You can see the full result here: http://pastebin.com/gcTN8xGp I have two questions; firstly is there a way to suppress all the noise? --show-below-main is set to no by default, but there doesn't appear to be a --show-after-main equivalent.

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  • Are document-oriented databases any more suitable than relational ones for persisting objects?

    - by Owen Fraser-Green
    In terms of database usage, the last decade was the age of the ORM with hundreds competing to persist our object graphs in plain old-fashioned RMDBS. Now we seem to be witnessing the coming of age of document-oriented databases. These databases are highly optimized for schema-free documents but are also very attractive for their ability to scale out and query a cluster in parallel. Document-oriented databases also hold a couple of advantages over RDBMS's for persisting data models in object-oriented designs. As the tables are schema-free, one can store objects belonging to different classes in an inheritance hierarchy side-by-side. Also, as the domain model changes, so long as the code can cope with getting back objects from an old version of the domain classes, one can avoid having to migrate the whole database at every change. On the other hand, the performance benefits of document-oriented databases mainly appear to come about when storing deeper documents. In object-oriented terms, classes which are composed of other classes, for example, a blog post and its comments. In most of the examples of this I can come up with though, such as the blog one, the gain in read access would appear to be offset by the penalty in having to write the whole blog post "document" every time a new comment is added. It looks to me as though document-oriented databases can bring significant benefits to object-oriented systems if one takes extreme care to organize the objects in deep graphs optimized for the way the data will be read and written but this means knowing the use cases up front. In the real world, we often don't know until we actually have a live implementation we can profile. So is the case of relational vs. document-oriented databases one of swings and roundabouts? I'm interested in people's opinions and advice, in particular if anyone has built any significant applications on a document-oriented database.

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  • What some good PHP jobs?

    - by ggfan
    I am no professional PHP coder or anything, in fact I am fairly new. I can develop sites but nothing too crazy or fancy with PHP,Mysql,CSS,HTML,javascript. Up to now, all I have been doing is practice coding from books and websites. I am now looking for a 'real-life' experience. Besides going to a company and getting an interview, are there any other options in which I can get paid to code? I have posted some ads on craiglists but that's about it. And because this is my first time going to the 'real-word' and can make mistakes, am I liable if...a site I made for someone gets hacked and that person losses information?

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  • Are there any design-patterns specifically useful for game-development?

    - by Baelnorn
    This question's been bugging me for a long time. I've always wondered how game developers were solving certain problems or situations that are quite common in certain genres. For example, how would one implement the quests of a typical role-playing game (e.g. BG or TES)? Or how would you implement weapons with multiple stacking effects in a first-person shooter (e.g. the Shrink-gun or Freezer from DN3D)? How would you implement multiple choice options with a possibly intricate decision tree leading to several different outcomes (e.g. the mission trees in WC)? Are there any examples or other resources for that? Blogs? Books? Sourcecode?

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  • Replace a word in an XML file through StreamReader in XNA?

    - by kcoppock
    Okay, so this is sort of a hack...but it may have to be. I'm writing an app in XNA, which from my research into this problem apparently doesn't support XML version 1.1. I'm reading in the contents of an ePub document, and one of the newer books contains its content directory as a version 1.1 XML document. This causes my program to crash. However, the structure is the same as the rest, the only thing that should be keeping it from working is the hard-coded "1.0" in the XmlDocument class. Is it possible that I could read in the file from the stream, see if it contains: <?xml version="1.1" encoding="UTF-8" standalone="no"?> and simply replace it with "1.0"? Then I could pull it in as an XmlDocument. I'm not doing any writing to the file, or any complex structural reading, just looking for a few specific nodes, and pulling in the values, so I don't know what the ramifications of this would be.

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  • Where can I take an online programming aptitude test/exam?

    - by nbolton
    A potential employer requires me to take an online aptitude test before my interview (in this case the test is for C, from Previsor). Where can I take the same (or similar) test so I have a rough idea on what I should brush up on? I've taken a similar test for C++ previously, so I have some idea of what to expect. I've also been studying my C books thoroughly (especially the required material as described in the PDF), but I feel it would be a good idea to get a feel for the particular test before taking it. I did a quick search on Brainbench, but they don't seem to have a C test, unless I'm mistaken (only C++). Note: I'm happy to pay to take a test if no decent free ones are available.

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  • Silverlight MVVM example which does not use data grids?

    - by Aim Kai
    I was wondering if anyone knew of a great example of using the MVVC pattern for a Silverlight application that does not utilise a data grid? Most of the examples I have read see links below and books such as Pro WPF and Silverlight MVVM by Gary Hall use a silverlight application with a datagrid. Don't get me wrong, these are all great examples. See also: MVVM: Tutorial from start to finish? http://www.silverlight.net/learn/tutorials/silverlight-4/using-the-mvvm-pattern-in-silverlight-applications/ However some recent demo projects I have been working are not necessarily dealing with data grids but I would still want to implement this pattern..

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  • Very weird C file-handling anomaly

    - by KáGé
    Hello, I got a very weird issue that I cant figure out in my school project, which is the simulation of a simple filesystem in a human-readable textfile. Unfortunately I don't yet have enough time to translate the comments in my code or make it less gibberish, so if you are bothered by that, you don't have to help, I understand. See the code HERE. Now in drive.h, at line 574 is this part: i = getline(); #ifdef DEBUG printf("Free space in all found at %d.\n\n", i); if(drive.disk != NULL){ printf("Disk OK\n\n"); } #endif //write in data state = seekline(i); Before this it finds place for the allocation database entry in the ALL sector (see the "image files" in the mounts folder, this issue was tested on mount_30.efs-dbf), then gets the line with i = getline() fine (getline is in lglobal.h, line 39), but after that any file manipulation (in this case seekline's fseek, but if I comment that out, then the first fprintf after that) crashes the program straight away. I think the file gets somehow corrupted (though the Disk OK message appears) but can't figure out how. I've tried putting i = getline(); into comment, but it didn't make any difference. I've also tried asking at local programming forums but they didn't really help either. The last few lines of the output before it crashes: Dir written. (drive.h line 562) Seekline entered: 268 (called at drive.h line 564) Getline entered. (called at drive.h line 574) Line got: 268. Free space in all found at 268. (drive.h line 576) Seekline entered: 268 (called at drive.h line 582, note that this exact call was run successfully less than 20 lines back. This one should set the pointer to the beginning of the line it is currently in) After this it crashes. Does anyone has any idea of what causes this and how could I fix it? Thank you.

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  • Fitch Format Proofs - any resources around?

    - by devoured elysium
    I am currently studying Fitch Format first order logic proofs. My lecturer follows closely Language, Proof and Logic by Jon Barwise. I am trying to do some proofs but I am having some trouble getting to understand how to do these proofs. As I have already read what Language Proof and Logic has to offer, I'd like to know if there are any other books or resources around that use the Fitch format for their formal proofs. Plus, having solved exercises would be of great(!) help. Thanks

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