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  • Should uni provide "correct answer" after programming assignment is due?

    - by Michael Mao
    Hi all: This is my very first subjective question. And I think it is programming related - the assignment is to be written in a programming language. I am not for "getting the full marks out of a subject". I am actually not for a "correct answer", but for a "better solution", so that I can compare, and can improve. I reckon it is good that I practice programming first and check the solution later to pick up the things I've done wrong/bad. Without a "benchmark" to against, this would be much harder. Unfortunately as far as I know, not all programming subjects taught in uni would kindly provide the students with a "correct answer" in the end, after the assignment is due. One bad metaphor for this is like someone asks you a question which they don't have a clear answer themselves and hope to take advantage of your answer as the basis for their answer. Personally, I feel having a assignment solution provided by the academic staff is essential to students. I do appreciate this, and I feel I might not be the only one. I am a very proactive student in uni. I learn more, I practice more, an assignment for me is more like a challenge to achieve "the best solution I can come up with", not something "I have to pass"... The cause of this question is that for the past few days I have crafted 500+ lines of Perl code, for a tiny assignment. I feel pain when I look at my solution(not finished yet) and I feel like I am an idiot doing some crap code. I know there must be a much better solution. And I reckon it is better for the lecturer in this subject to get me one, rather than asking for an answer here, even I would shamelessly add the link to my solution apart from the assignment requirements. I know in SO, there are a lot of tutors/lecturers for programming subjects/courses. I'd like to hear your words on this question.

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  • .net design pattern question

    - by user359562
    Hi. I am trying to understand design pattern problems. I am trying to modify the code like this in winforms and trying to see if any design pattern suits my requirement. Please suggest which is the best design pattern in this scenario. This is very basic code containing 2 tab pages which might have different controls can be added dynamically and read out different files on click of particular tab. To elaborate more... I have written this code to learn and understand design pattern. This is just a scenario where user click on a particular tab which will show dynamic controls generated. public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void tabControl1_SelectedIndexChanged(object sender, EventArgs e) { if (tabControl1.SelectedTab.Name.Equals("tabPage1")) { GeneratedynamicControlsForTab1(); } else if (tabControl1.SelectedTab.Name.Equals("tabPage2")) { GeneratedynamicControlsForTab2(); } } private void GeneratedynamicControlsForTab1() { Label label1 = new Label(); label1.Text = "Label1"; tabPage1.Controls.Add(label1); ReadCSVFile(); } private void GeneratedynamicControlsForTab2() { tabPage1.Controls.Clear(); Label label2 = new Label(); label2.Text = "Label2"; tabPage2.Controls.Add(label2); ReadTextFile(); } private void ReadCSVFile() { } private void ReadTextFile() { } }

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  • ASP.Net MVC - how can I easily serialize query results to a database?

    - by Mortanis
    I've been working on a little property search engine while I learn ASP.Net MVC. I've gotten the results from various property database tables and sorted them into a master generic property response. The search form is passed via Model Binding and works great. Now, I'd like to add pagination. I'm returning the chunk of properties for the current page with .Skip() and .Take(), and that's working great. I have a SearchResults model that has the paged result set and various other data like nextPage and prevPage. Except, I no longer have the original form of course to pass to /Results/2. Previously I'd have just hidden a copy of the form and done a POST each time, but it seems inelegant. I'd like to serialize the results to my MS SQL database and return a unique key for that results set - this also helps with a "Send this query to a friend!" link. Killing two birds with one stone. Is there an easy way to take an IQueryable result set that I have, serialize it, stick it into the DB, return a unique key and then reverse the process with said key? I'm using Linq to SQL currently on a MS SQL Express install, though in production it'll be on MS SQL 2008.

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  • best REGEXP friendly Text Editors + most powerful REGEXP syntax?

    - by John
    I am fluent with Microsoft Visual 2005 regular expressions and they are a big time saver. I seem to learn them best by having a vaguely organized cheat sheet thrown at me, at which point I read just a little and play with them until I understand what's going on. That learning approach has worked well for me, for now. I would really like to take this to the next level though. Basically -- What is the REGEXP convention that is generally regarded as the most open-ended and powerful? VS2005 Regexps seem kind of gimped, so maybe I'm a kid playing in a sandbox. Are there text editors out there that can perform a highlight all matches, list lines containing string, or some kind of powerful function like that in conjunction with the very strongest REGEXP language? If not I can just use multiple programs and a weird technique but I'd like to avoid that. I wonder if a stronger REGEXP language or a "stronger" regEXP writer might be able to have his search match all results on all lines even by clicking a "find next" by adding some simple criteria to the search. Anyway, please provide advice!

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  • What is the best cross-platform language for desktop applications? (Java, Adobe Air, Flex, Silverlight??, Anything Else)

    - by Sootah
    My business partner needs a desktop application programmed, and it needs to be cross-platform as he wants Mac owners (OS X) to be able to run it as well. This, of course, is a bit of a problem for me as I program in PHP for my web projects and exclusively in C# (formerly used Visual Basic) for my desktop apps. I've been using (and love) NetBeans for my PHP stuff, and love Visual Studio just as much; they're both excellent IDEs. With this in mind, I'd like to find a language and IDE that's as similar to Visual Studio as possible (or at least something that makes development as easy as it does) for my cross-platform application development. In fact, if there is a language I can use with VS I'd be extremely happy. I realize that NetBeans has a Java Desktop App IDE, but have been having problems with it (my question in regards to that issue is here. I am also not sure that I really want to learn and use Java if there is a better, easier option out there. Obviously, the first language that came to mind that I can use cross-platform was Java, but I've also heard of people using Adobe Air, as well as Flex being used. I've never programmed in any of those languages, and as such have no frame of reference from which I can decide which would be best for me. I'm also not sure what other options there may be for me; perhaps there's another language I can use that'd be better than the three options I've already provided. (Can you make desktop apps with Silverlight? If so, did MS make an interpreter that will get them to work on OS X?) I like the syntax of C# quite a bit, and the Visual Studio IDE makes it extremely easy to make my apps with. As such, I'd like to find something that'll work as well for me with the cross-platform shatner as C# and its IDE does with my Windows apps. Thanks in advance for your help/opinions!

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  • Centering in IE5/6/7/8, and FF

    - by splatto
    I'm trying to centre the content of a div such that the display is correct in IE 5,6,7 and 8, as well as FF. <div id="YoutubeClip"> <h3>Subscribe on YouTube!</h3><br> <ul class="gallery clearfix"><a href="http://www.someyoutubevideo.com" rel="prettyPhoto" title="Some youtube title"><img alt="some youtube title" src="youtube clip image" border="0"></a></ul> Some youtube title </div> As expected, this displays the image and the text centered in FF. In IE5, the image is left justified. The text is also left justified, with only one word on a line. It appears like this. IE 6 has the same problem as above. IE 7 appears to have the same problem, but when I put a border around the div, the content overflows the border. The display appears correct in IE8 Any help into this would be great. I'm trying to learn CSS better and I haven't been able to figure out the intricacies of this issue yet.

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  • C# + Querying XML with LINQ

    - by user336786
    Hello, I'm learning to use LINQ. I have seen some videos online that have really impressed me. In an effort to learn LINQ myself, I decided to try to write a query to the NOAA web service. If you put "http://www.weather.gov/forecasts/xml/sample_products/browser_interface/ndfdBrowserClientByDay.php?zipCodeList=20001&format=24+hourly&startDate=2010-06-10&numDays=5" in your browser's address bar, you will see some XML. I have successfully retrieved that XML in a C# program. I am loading the XML into a LINQable entity by doing the following: string xml = QueryWeatherService(); XDocument weather = XDocument.Parse(xml); I have a class called DailyForecast defined as follows: public class DailyForecast { public float HighTemperature { get; set; } public float LowTemperature { get; set; } public float PrecipitationPossibility { get; set; } public string WeatherSummary { get; set; } } I'm trying write a LINQ query that adheres to the structure of my DailyForecast class. At this time, I've only gotten to this far: var results = from day in response.Descendants("parameters") select day; Not very far I know. Because of the structure of the XML returned, I'm not sure it is possible to solely use a LINQ query. I think the only way to do this is via a loop and traverse the XML. I'm seeking someone to correct me if I'm wrong. Can someone please tell me if I can get results using purely LINQ that adhere to the structure of the DailyForecast class? If so, how? Thank you!

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  • Python program to search for specific strings in hash values (coding help)

    - by Diego
    Trying to write a code that searches hash values for specific string's (input by user) and returns the hash if searchquery is present in that line. Doing this to kind of just learn python a bit more, but it could be a real world application used by an HR department to search a .csv resume database for specific words in each resume. I'd like this program to look through a .csv file that has three entries per line (id#;applicant name;resume text) I set it up so that it creates a hash, then created a string for the resume text hash entry, and am trying to use the .find() function to return the entire hash for each instance. What i'd like is if the word "gpa" is used as a search query and it is found in s['resumetext'] for three applicants(rows in .csv file), it prints the id, name, and resume for every row that has it.(All three applicants) As it is right now, my program prints the first row in the .csv file(print resume['id'], resume['name'], resume['resumetext']) no matter what the searchquery is, whether it's in the resumetext or not. lastly, are there better ways to doing this, by searching word documents, pdf's and .txt files in a folder for specific words using python (i've just started reading about the re module and am wondering if this may be the route, rather than putting everything in a .csv file.) def find_details(id2find): resumes_f=open("resume_data.csv") for each_line in resumes_f: s={} (s['id'], s['name'], s['resumetext']) = each_line.split(";") resumetext = str(s['resumetext']) if resumetext.find(id2find): return(s) else: print "No data matches your search query. Please try again" searchquery = raw_input("please enter your search term") resume = find_details(searchquery) if resume: print resume['id'], resume['name'], resume['resumetext']

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  • Adding google font api to select menu

    - by Vivek Dragon
    I am making a select menu with all the fonts in google fonts API. I have referred this https://developers.google.com/webfonts/docs/developer_api link to learn more about API but till now i was not able to make it. I am adding this Fiddle which i made for this. HTML <select id="styleFont"> <option value="0">Myraid Pro</option> <option value="1">Sans ref</option> <option value="2">Times New Roman</option> <option value="3"> Arial</option> </select> <br> <textarea id="custom_text"></textarea> CSS #custom_text{ resize: none;}? Script $("#styleFont").change(function () { var id =$('#styleFont option' + ':selected').text(); $("#custom_text").css('font-family',id); });? How can i link those fonts to my select box in the fiddle?

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  • Haskell Cons Operator (:)

    - by Carson Myers
    I am really new to Haskell (Actually I saw "Real World Haskell" from O'Reilly and thought "hmm, I think I'll learn functional programming" yesterday) and I am wondering: I can use the construct operator to add an item to the beginning of a list: 1 : [2,3] [1,2,3] I tried making an example data type I found in the book and then playing with it: --in a file data BillingInfo = CreditCard Int String String | CashOnDelivery | Invoice Int deriving (Show) --in ghci $ let order_list = [Invoice 2345] $ order_list [Invoice 2345] $ let order_list = CashOnDelivery : order_list $ order_list [CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, ...- etc... it just repeats forever, is this because it uses lazy evaluation? -- EDIT -- okay, so it is being pounded into my head that let order_list = CashOnDelivery:order_list doesn't add CashOnDelivery to the original order_list and then set the result to order_list, but instead is recursive and creates an infinite list, forever adding CashOnDelivery to the beginning of itself. Of course now I remember that Haskell is a functional language and I can't change the value of the original order_list, so what should I do for a simple "tack this on to the end (or beginning, whatever) of this list?" Make a function which takes a list and BillingInfo as arguments, and then return a list? -- EDIT 2 -- well, based on all the answers I'm getting and the lack of being able to pass an object by reference and mutate variables (such as I'm used to)... I think that I have just asked this question prematurely and that I really need to delve further into the functional paradigm before I can expect to really understand the answers to my questions... I guess what i was looking for was how to write a function or something, taking a list and an item, and returning a list under the same name so the function could be called more than once, without changing the name every time (as if it was actually a program which would add actual orders to an order list, and the user wouldn't have to think of a new name for the list each time, but rather append an item to the same list).

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  • Questions about the Backpropogation Algorithm

    - by Colemangrill
    I have a few questions concerning backpropogation. I'm trying to learn the fundamentals behind neural network theory and wanted to start small, building a simple XOR classifier. I've read a lot of articles and skimmed multiple textbooks - but I can't seem to teach this thing the pattern for XOR. Firstly, I am unclear about the learning model for backpropogation. Here is some pseudo-code to represent how I am trying to train the network. [Lets assume my network is setup properly (ie: multiple inputs connect to a hidden layer connect to an output layer and all wired up properly)]. SET guess = getNetworkOutput() // Note this is using a sigmoid activation function. SET error = desiredOutput - guess SET delta = learningConstant * error * sigmoidDerivative(guess) For Each Node in inputNodes For Each Weight in inputNodes[n] inputNodes[n].weight[j] += delta; // At this point, I am assuming the first layer has been trained. // Then I recurse a similar function over the hidden layer and output layer. // The prime difference being that it further divi's up the adjustment delta. I realize this is probably not enough to go off of, and I will gladly expound on any part of my implementation. Using the above algorithm, my neural network does get trained, kind of. But not properly. The output is always XOR 1 1 [smallest number] XOR 0 0 [largest number] XOR 1 0 [medium number] XOR 0 1 [medium number] I can never train the [1,1] [0,0] to be the same value. If you have any suggestions, additional resources, articles, blogs, etc for me to look at I am very interested in learning more about this topic. Thank you for your assistance, I appreciate it greatly!

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  • "Finding" an object instance of a known class?

    - by Sean C
    My first post here (anywhere for that matter!), re. Cocoa/Obj-C (I'm NOT up to speed on either, please be patient!). I hope I haven't missed the answer already, I did try to find it. I'm an old-school procedural dog (haven't done any programming since the mid 80's, so I probably just can't even learn new tricks), but OOP has my head spinning! My question is: is there any means at all to "discover/find/identify" an instance of an object of a known class, given that some OTHER unknown process instantiated it? eg. somthing that would accomplish this scenario: (id) anObj = [someTarget getMostRecentInstanceOf:[aKnownClass class]]; for that matter, "getAnyInstance" or "getAllInstances" might do the trick too. Background: I'm trying to write a plugin for a commercial application, so much of the heavy lifting is being done by the app, behind the scenes. I have the SDK & header files, I know what class the object is, and what method I need to call (it has only instance methods), I just can't identify the object for targetting. I've spent untold hours and days going over Apples documentation, tutorials and lots of example/sample code on the web (including here at Stack Overflow), and come up empty. Seems that everything requires a known target object to work, and I just don't have one. Since I may not be expressing my problem as clearly as needed, I've put up a web page, with diagram & working sample pages to illustrate: http://www.nulltime.com/svtest/index.html Any help or guidance will be appreciated! Thanks.

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  • AJAX filter MySQL results using checkboxes

    - by keepitnang
    I'm attempting to get to grips with displaying filterable MySQL data within a PHP page based on user checkbox selections. I have a database of domain names and the dates on which these will require renewal as per Nominet DAC information and I can get unfiltered data to display, but filtering results by domain extensions is proving tricky for me to accomplish. I should point out at this stage that I am a serious newcomer to many of the ideas I am trying to learn to work with here, so please be gentle. I have tried following some other articles on here also, but no dice. I have the following so far: HTML <input type="checkbox" class="extensions" name="extensions" value=".co.uk">.co.uk</input> <input type="checkbox" class="extensions" name="extensions" value=".org.uk">.org.uk</input> Script $('.extensions').live('click', function() { var all_boxes = $('.extensions'); var all_boxes_values = []; var i = 0; for (var i; i < all_boxes.length; i++) { if (all_boxes[i].checked) { all_boxes_values.push(all_boxes[i].value) } } var all_boxes_values_clean = all_boxes_values.join(", "); console.log(all_boxes_values_clean); $.get("sql-test.php", {q: all_boxes_values_clean}, function(result) { $("div#output").html(result); } )}); PHP $g = $_GET['q']; $extensionsql=""; $extension=1; if(isset($g)) { $extension=1; $param = "" . str_replace(",", "','", $_GET['q']) . ""; } And that's as far as I have gotten with my limited ability. What I would like to do next is search the column domainName for a string match and return the appropriate results to the user. Something to mimic something like the following but I'm not sure how to achieve it. Any help would be much appreciated: SELECT * FROM `refresh` WHERE `domainName` LIKE '%.co.uk%' AND renewalDate LIKE '%2012-06-30%' ORDER BY `domainName` ASC Thanks

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  • Please help with C++ syntax for const accessor by reference.

    - by Hamish Grubijan
    Right not my implementation returns the thing by value. The member m_MyObj itself is not const - it's value changes depending on what the user selects with a Combo Box. I am no C++ guru, but I want to do this right. If I simply stick a & in front of GetChosenSourceSystem in both decl. and impl., I get one sort of compiler error. If I do one but not another - another error. If I do return &m_MyObj;. I will not list the errors here for now, unless there is a strong demand for it. I assume that an experienced C++ coder can tell what is going on here. I could omit constness or reference, but I want to make it tight and learn in the process as well. Thanks! // In header file MyObj GetChosenThingy() const; // In Implementation file. MyObj MyDlg::GetChosenThingy() const { return m_MyObj; }

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  • What Test Environment Setup do Committers Use in the Ruby Community?

    - by viatropos
    Today I am going to get as far as I can setting up my testing environment and workflow. I'm looking for practical advice on how to setup the test environment from you guys who are very passionate and versed in Ruby Testing. By the end of the day (6am PST?) I would like to be able to: Type one 1-command to run test suites for ANY project I find on Github. Run autotest for ANY Github project so I can fork and make TESTABLE contributions. Build gems from the ground up with Autotest and Shoulda. For one reason or another, I hardly ever run tests for projects I clone from Github. The major reason is because unless they're using RSpec and have a Rake task to run the tests, I don't see the common pattern behind it all. I have built 3 or 4 gems writing tests with RSpec, and while I find the DSL fun, it's less than ideal because it just adds another layer/language of methods I have to learn and remember. So I'm going with Shoulda. But this isn't a question about which testing framework to choose. So the questions are: What is your, the SO reader and Github project committer, test environment setup using autotest so that whenever you git clone a gem, you can run the tests and autotest-develop them if desired? What are the guys who are writing the Paperclip Tests and Authlogic Tests doing? What is their setup? Thanks for the insight. Looking for answers that will make me a more effective tester.

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  • How do I write recursive anonymous functions?

    - by James T Kirk
    In my continued effort to learn scala, I'm working through 'Scala by example' by Odersky and on the chapter on first class functions, the section on anonymous function avoids a situation of recursive anonymous function. I have a solution that seems to work. I'm curious if there is a better answer out there. From the pdf: Code to showcase higher order functions def sum(f: Int => Int, a: Int, b: Int): Int = if (a > b) 0 else f(a) + sum(f, a + 1, b) def id(x: Int): Int = x def square(x: Int): Int = x * x def powerOfTwo(x: Int): Int = if (x == 0) 1 else 2 * powerOfTwo(x-1) def sumInts(a: Int, b: Int): Int = sum(id, a, b) def sumSquares(a: Int, b: Int): Int = sum(square, a, b) def sumPowersOfTwo(a: Int, b: Int): Int = sum(powerOfTwo, a, b) scala> sumPowersOfTwo(2,3) res0: Int = 12 from the pdf: Code to showcase anonymous functions def sum(f: Int => Int, a: Int, b: Int): Int = if (a > b) 0 else f(a) + sum(f, a + 1, b) def sumInts(a: Int, b: Int): Int = sum((x: Int) => x, a, b) def sumSquares(a: Int, b: Int): Int = sum((x: Int) => x * x, a, b) // no sumPowersOfTwo My code: def sumPowersOfTwo(a: Int, b: Int): Int = sum((x: Int) => { def f(y:Int):Int = if (y==0) 1 else 2 * f(y-1); f(x) }, a, b) scala> sumPowersOfTwo(2,3) res0: Int = 12

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  • What runs faster? Wordpress or Drupal 6.x?

    - by electblake
    So... I run a pretty large Wordpress blog. Currently it gets around 20k+ pageviews a day, and its always a struggle to keep the bad boy running quickly - I currently run a vps.net with CentOS 5.3 I am also Drupal developer by trade so I love the CMS Framework for its versatility and the portability (I can take work from one site and implement on another with great ease) MY QUESTION IS: What is faster then? Wordpress 3.x & Drupal 6.x I'd love to migrate my site to Drupal to be able to roll out new features etc (which I find awkward to do in Wordpress) but I am scared that Drupal may not be able to handle the traffic. Any opinions? I know that some major players use Drupal - as Dries documents well on his blog but I'm not under any illusions that Drupal can be a real hog. Thanks for any/all help! Please try to avoid server optimization talk unless it pertains to Wordpress or Drupal 6.x specifically, I love to learn more about optimizations but I do want to sort out which platform is quicker :) p.s - I realize the fastest option is to use a lower-level framework (with less overhead) like CakePHP etc but assume that isn't an option ;)

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  • How difficult is it for an old-school programmer to pick up an FPGA kit and make something useful wi

    - by JUST MY correct OPINION
    I'm an old, old, old coder. (How old? I've used paper tape in anger.) I've programmed in a lot of languages and under a lot of paradigms (spaghetti, structured, object-oriented, functional and a smattering of logical). I'm getting bored. FPGAs look interesting to me. I have the crazy notion of resurrecting some of the ancient hardware I worked on in the days using FPGAs. I know this can be done because I've seen PDP-10 and PDP-11 implementations in FPGAs. I'd like to do the same for a few machines that are perhaps not as popular as those two, however. While I am an old, old coder, what I am not is an electronics or computer systems engineer. I'll be learning from scratch if I go down this path. My question, therefore, is two-fold: How difficult will it be for this old dinosaur to pick up and learn FPGAs to the point that interesting (not necessarily practical -- more from a hobbyist perspective) projects can be made? What should I start with learning-wise to go down this path? I know where to get FPGA kits, but I haven't found anything like "FPGAs for Complete Dinosaurs" yet anywhere out there.

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  • What are major differences between C# and Java?

    - by enba
    I just want to clarify one thing. This is not a question on which one is better, that part I leave to someone else to discuss. I don't care about it. I've been asked this question on my job interview and I thought it might be useful to learn a bit more. These are the ones I could come up with: Java is "platform independent". Well nowadays you could say there is the Mono project so C# could be considered too but I believe it is a bit exaggerating. Why? Well, when a new release of Java is done it is simultaneously available on all platforms it supports, on the other hand how many features of C# 3.0 are still missing in the Mono implementation? Or is it really CLR vs. JRE that we should compare here? Java doesn't support events and delegates. As far as I know. In Java all methods are virtual Development tools: I believe there isn't such a tool yet as Visual Studio. Especially if you've worked with team editions you'll know what I mean. Please add others you think are relevant. Update: Just popped up my mind, Java doesn't have something like custom attributes on classes, methods etc. Or does it?

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  • C# Changing Objects within a List

    - by kwong22
    Hi, I'm having a little problem changing members of an object in a list using a found index. So this is the method I am currently working with: static void addToInventory(ref List<baseItem> myArray, baseItem item, float maxAmount, ref float currentAmount) { if (currentAmount + item.getWeight() <= maxAmount) { Console.WriteLine("item.Quantity = {0}", item.Quantity); if (myArray.Contains(item)) { Console.WriteLine("Item ({0}) already exists", item.Name); int id = myArray.IndexOf(item); myArray[id].Quantity += item.Quantity;//Change occurs in this line, item.Quantity becomes the same as myArray[id].Quantity } else { Console.WriteLine("Adding new item ({0})", item.Name); myArray.Add(item); } currentAmount += item.getWeight(); } else { Console.WriteLine("Inventory full"); } myArray.Sort(); } This method takes several parameters including the inventory/list. I check if the item fits in and if it does, I see if there is another item of the same name in the list, find the index, and add more of the item. However, the quantity of the item added suddenly becomes the same as the quantity of the item in the list. For some reason, this also changes the quantity of the item outside of the list. So therefore, instead of quantities adding up like this: 1, 2, 3, 4, they add up like this: 1, 2, 4, 8. I've just started to learn how to use lists so if there is anything I'm missing, don't hesitate to criticize. Thanks in advance.

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  • Understanding the singleton class when aliasing a instance method

    - by Backo
    I am using Ruby 1.9.2 and the Ruby on Rails v3.2.2 gem. I am trying to learn Metaprogramming "the right way" and at this time I am aliasing an instance method in the included do ... end block provided by the RoR ActiveSupport::Concern module: module MyModule extend ActiveSupport::Concern included do # Builds the instance method name. my_method_name = build_method_name.to_sym # => :my_method # Defines the :my_method instance method in the including class of MyModule. define_singleton_method(my_method_name) do |*args| # ... end # Aliases the :my_method instance method in the including class of MyModule. singleton_class = class << self; self end singleton_class.send(:alias_method, :my_new_method, my_method_name) end end "Newbiely" speaking, with a search on the Web I came up with the singleton_class = class << self; self end statement and I used that (instead of the class << self ... end block) in order to scope the my_method_name variable, making the aliasing generated dynamically. I would like to understand exactly why and how the singleton_class works in the above code and if there is a better way (maybe, a more maintainable and performant one) to implement the same (aliasing, defining the singleton method and so on), but "the right way" since I think it isn't so.

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  • Concise description of how .h and .m files interact in objective c?

    - by RJ86
    I have just started learning objective C and am really confused how the .h and .m files interact with each other. This simple program has 3 files: Fraction.h #import <Foundation/NSObject.h> @interface Fraction : NSObject { int numerator; int denominator; } - (void) print; - (void) setNumerator: (int) n; - (void) setDenominator: (int) d; - (int) numerator; - (int) denominator; @end Fraction.m #import "Fraction.h" #import <stdio.h> @implementation Fraction -(void) print { printf( "%i/%i", numerator, denominator ); } -(void) setNumerator: (int) n { numerator = n; } -(void) setDenominator: (int) d { denominator = d; } -(int) denominator { return denominator; } -(int) numerator { return numerator; } @end Main.m #import <stdio.h> #import "Fraction.h" int main(int argc, char *argv[]) { Fraction *frac = [[Fraction alloc] init]; [frac setNumerator: 1]; [frac setDenominator: 3]; printf( "The fraction is: " ); [frac print]; printf( "\n" ); [frac release]; return 0; } From what I understand, the program initially starts running the main.m file. I understand the basic C concepts but this whole "class" and "instance" stuff is really confusing. In the Fraction.h file the @interface is defining numerator and denominator as an integer, but what else is it doing below with the (void)? and what is the purpose of re-defining below? I am also quite confused as to what is happening with the (void) and (int) portions of the Fraction.m and how all of this is brought together in the main.m file. I guess what I am trying to say is that this seems like a fairly easy program to learn how the different portions work with each other - could anyone explain in non-tech jargon?

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  • I'm graduating with a Computer Science degree but I don't feel like I know how to program.

    - by Wendy Peters
    I'm graduating with a Computer Science degree but I see websites like Stackoverflow and search engines like Google and don't know where I'd even begin to write something like that. During one summer I worked as a iPhone developer, but I felt like I was mostly gluing together libraries that other people had written with little understanding of what's happening underneath the hood. I'm trying to improve my knowledge by studying algorithms, but it is a long and painful process. I find algorithms difficult and at the rate I am working through my book it will a decade will have passed before I will finish. Given my current situation, I've spent a month looking for work but my skills (C, Python, Objective-C) are not so desirable in the local market, where C#, Java, and web development are much higher in demand. My GPA is ok (3.0) but it's not high enough to apply to the large companies or return for graduate studies and I don't have a good network of friends. Basically I'm graduating with a Computer Science degree but I don't feel like I know how to program. I thought that joining a company and programming full-time would give me a chance to develop my skills and learn from those more experienced than myself, but I'm struggling to find work and am starting to get really frustrated. I am going to cast my net wider and look beyond the city I've grown up in, but what have other people in similar situation tried to do?

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  • How to delete a row from a typed dataset and save it to a database?

    - by Zingam
    I am doing this as a small project to learn about disconnected and connected models in .NET 4.0 and SQL Server 2008 R2. I have three tables: Companies (PK CompanyID) Addresses (PK AddressID, FK CompanyID) ContactPersons (PK ContactPersonID, FK CompanyID) CompanyID is assigned manually by the users. The other IDs are auto-generated. Companies has a one-to-many relationship with ContactPerson. I have set any changes to cascade. I display all records in Companies in a DataGridView and when a row is clicked, the corresponding records in ContactPersons are displayed in a second DataGridView. I have successfully implemented updating and inserting new records but I completely fail in my attempts to delete rows and save the changes to the database. I us a typed dataset. If I use this: DataRow[] contactPersonRows = m_SoldaCompaniesFileDataSet.ContactPersons.Select("ContactPersonID = " + this.m_CurrentContactPerson.ContactPersonID); m_SoldaCompaniesFileDataSet.ContactPersons.Rows.Remove(contactPersonRows[0]); The records are displayed properly in the DataGridView but are not saved in the database later. If I use this: DataRow row = m_SoldaCompaniesFileDataSet.ContactPersons.Rows.Find(this.m_CurrentContactPerson.ContactPersonID); row.Delete(); The records are set but I get an exeception: DeletedRowInaccessibleException, when I try to refresh the DataGridView. The exception pop-s up in the auto-generated dataset.design file. I am pretty much stuck at this point since yesterday. I cannot find anything anywhere that remotely resembles my problem. And I cannot understand actually what is going on.

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  • identifier ... is undefined when trying to run pure C code in Cuda using nvcc

    - by Lostsoul
    I'm new and learning Cuda. A approach that I'm trying to use to learn is to write code in C and once I know its working start converting it to Cuda since I read that nvcc compiles Cuda code but complies everything else using plain old c. My code works in c(using gcc) but when I try to compile it using nvcc(after changing the file name from main.c to main.cu) I get main.cu(155): error: identifier "num_of_rows" is undefined main.cu(155): error: identifier "num_items_in_row" is undefined 2 errors detected in the compilation of "/tmp/tmpxft_00002898_00000000-4_main.cpp1.ii". Basically in my main method I send data to a function like this: process_list(count, countListItem, list); the first two items are ints and the last item(list) is a matrix. Then I create my function like this: void process_list(int num_of_rows, int num_items_in_row, int current_list[num_of_rows][num_items_in_row]) { This line is where I get my errors when using nvcc(line 155). I need to convert this code to cuda anyway so no need to troubleshoot this specific issue(plus code is quite large) but I'm wondering if I'm wrong about nvcc treating the C part of your code like plain C. In the book cuda by example I just used nvcc to compile but do I need any extra flags when just using pure c?

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