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  • Plugin architecture in C using libdl

    - by LukeN
    I've been toying around, writing a small IRC framework in C that I'm now going to expand with some core functionality - but beyond that, I'd like it to be extensible with plugins! Up until now, whenever I wrote something IRC related (and I wrote a lot, in about 6 different languages now... I'm on fire!) and actually went ahead to implement a plugin architecture, it was inside an interpreted language that had facilities for doing (read: abusing) so, like jamming a whole script file trough eval in Ruby (bad!). Now I want to abuse something in C! Basically there's three things I could do define a simple script language inside of my program use an existing one, embedding an interpreter use libdl to load *.so modules on runtime I'm fond of the third one and raather avoid the other two options if possible. Maybe I'm a masochist of some sort, but I think it could be both fun and useful for learning purposes. Logically thinking, the obvious "pain-chain" would be (lowest to highest) 2 - 1 - 3, for the simple reason that libdl is dealing with raw code that can (and will) explode in my face more often than not. So this question goes out to you, fellow users of stackoverflow, do you think libdl is up to this task, or even a realistic thought?

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  • c# - sqllite dosnt save data i inserted

    - by samy
    I'm messing around with SQL lite and learning it. I got a table called People, I got some method that connect to the database and do some stuff, like show all the info. Now I'm trying to insert some data and here it get wierd for me. I have this method: private void ExecuteQuery(string txtQuery) { SetConnection(); sql_con.Open(); sql_cmd = sql_con.CreateCommand(); sql_cmd.CommandText = txtQuery; sql_cmd.ExecuteNonQuery(); sql_con.Close(); } and to see all the data I've got this method: private void LoadData() { SetConnection(); sql_con.Open(); sql_cmd = sql_con.CreateCommand(); string CommandText = "SELECT * FROM People"; DB = new SQLiteDataAdapter(CommandText, sql_con); DS.Reset(); DB.Fill(DS); DT = DS.Tables[0]; dataGridView1.DataSource = DT; sql_con.Close(); } When I inset some data and right afther it I call the LoadData(), I can see all the changes I made. After I close the program, and then open it agian and call LoadData(), I don't see the new info that I inserted before. I got some data that I used SQL lite GUI app to insert, and I can see that data every time I call the LoadData() method, but not mine. Do I need to do somthing else to make sure SQL lite saves all the data?

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  • Which design pattern fits - strategy makes sense ?

    - by user554833
    --Bump *One desperate try to get someone's attention I have a simple database table that stores list of users who have subscribed to folders either by email OR to show up on the site (only on the web UI). In the storage table this is controlled by a number(1 - show on site 2- by email). When I am showing in UI I need to show a checkbox next to each of folders for which the user has subscribed (both email & on site). There is a separate table which stores a set of default subscriptions which would apply to each user if user has not expressed his subscription. This is basically a folder ID and a virtual group name. But, Email subscriptions do not count for applying these default groups. So if no "on site" subscription apply default group. Thats the rule. How about a strategy pattern here (Pseudo code) Interface ISubscription public ArrayList GetSubscriptionData(Pass query object) Public class SubscriptionWithDefaultGroup Implement ArrayList GetSubscriptionData(Pass query object) Public class SubscriptionWithoutDefaultGroup Implement ArrayList GetSubscriptionData(Pass query object) Public class SubscriptionOnlyDefaultGroup Implement ArrayList GetSubscriptionData(Pass query object) does this even make sense? I would be more than glad for receive any criticism / help / notes. I am learning. Cheers

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  • how to make custom ROMs for lesser-known Android devices (i.e., WellcoM A69)

    - by gonzobrains
    Hi, I have a WellcoM A69 Android phone I would like to start hacking. I bought it in Thailand (I think WellcoM is a Thai company). However, the docs don't explain how to get a recovery menu or anything like that. I would like to figure out how to make custom ROMs for it, because it doesn't have any Google Experience apps and I also want to change the boot screen. How can I go about doing this? If I can't do this, I want to at least be able to use the device in the Eclipse debugger. I select the debugging option under applications but the device still isn't recognized. Is this something that can be disabled by the manufacturer? In any case, I would like to re-enable it if a custom ROM can allow this. If this cannot be done at all, please at least point me in the direction of where I can start writing/building my own ROMs for the G1? I figured that would be a good starting point for learning. Thanks, Jeff

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  • Is `super` local variable?

    - by Michael
    // A : Parent @implementation A -(id) init { // change self here then return it } @end A A *a = [[A alloc] init]; a. Just wondering, if self is a local variable or global? If it's local then what is the point of self = [super init] in init? I can successfully define some local variable and use like this, why would I need to assign it to self. -(id) init { id tmp = [super init]; if(tmp != nil) { //do stuff } return tmp; } b. If [super init] returns some other object instance and I have to overwrite self then I will not be able to access A's methods any more, since it will be completely new object? Am I right? c. super and self pointing to the same memory and the major difference between them is method lookup order. Am I right? sorry, don't have Mac to try, learning theory as for now...

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  • Cake returned the time consumed in data lookup in JQuery Alert Box

    - by kwokwai
    Hi all, When I was doing some self-learning on JQuery Ajax in Cakephp, I found out some strange behaviour in the JQuery Alert Box. Here are a few lines of code of the JQuery Ajax I used: $(document).ready(function(){ $(document).change(function(){ var usr = $("#data\\[User\\]\\[name\\]").val(); $.post{"http://www.mywebsite.com/controllers/action/", usr, function(msg){alert(msg);} } }); }); The Alert box shows me a message returned from the Action: Helloworld <!--0.656s--> I am not sure why the number of time consumption was displayed in the Alert box, since it was not in my code as follows: function action($data=null){ $this->autoRender = false; $result2=$this->__avail($data); if($result2==1) {return "OK";} else {return "NOT";} } CakePHP rteurned some extra information in the Alert box. Later I altered a single line of code and tried out this instead, and the time consumption was not displayed on screen then: $(document).ready(function(){ $(document).change(function(){ var usr = $("#data\\[User\\]\\[name\\]").val(); $.post{"http://www.mywebsite.com/controllers/action/", usr, function(msg){$("#username").append('<span>'+msg+</span'>);} } }); });

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  • How can I have a single helper work on different models passed to it?

    - by Angela
    I am probably going to need to refactor in two steps since I'm still developing the project and learning the use-cases as I go along since it is to scratch my own itch. I have three models: Letters, Calls, Emails. They have some similarilty, but I anticipate they also will have some different attributes as you can tell from their description. Ideally I could refactor them as Events, with a type as Letters, Calls, Emails, but didn't know how to extend subclasses. My immediate need is this: I have a helper which checks on the status of whether an email (for example) was sent to a specific contact: def show_email_status(contact, email) @contact_email = ContactEmail.find(:first, :conditions => {:contact_id => contact.id, :email_id => email.id }) if ! @contact_email.nil? return @contact_email.status end end I realized that I, of course, want to know the status for whether a call was made to a contact as well, so I wrote: def show_call_status(contact, call) @contact_call = ContactCall.find(:first, :conditions => {:contact_id => contact.id, :call_id => call.id }) if ! @contact_call.nil? return @contact_call.status end end I would love to be able to just have a single helper show_status where I can say show_status(contact,call) or show_status(contact,email) and it would know whether to look for the object @contact_call or @contact_email. Yes, it would be easier if it were just @contact_event, but I want to do a small refactoring while I get the program up and running, and this would make the ability to do a history for a given contact much easier. Thanks!

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  • Is this the correct way to set up has many with multiple associations?

    - by user323763
    I'm trying to set up a new project for a music site. I'm learning ROR and am a bit confused about how to make join models/tables. Does this look right? I have users, playlists, songs, and comments. Users can have multiple playlists. Users can have multiple comments on their profile. Playlists can have multiple songs. Playlists can have comments. Songs can have comments. class CreateTables < ActiveRecord::Migration def self.up create_table :users do |t| t.string :login t.string :email t.string :firstname t.string :lastname t.timestamps end create_table :playlists do |t| t.string :title t.text :description t.timestamps end create_table :songs do |t| t.string :title t.string :artist t.string :album t.integer :duration t.string :image t.string :source t.timestamps end create_table :comments do |t| t.string :title t.text :body t.timestamps end create_table :users_playlists do |t| t.integer :user_id t.integer :playlist_id t.timestamps end create_table :playlists_songs do |t| t.integer :playlist_id t.integer :song_id t.integer :position t.timestamps end create_table :users_comments do |t| t.integer :user_id t.integer :comment_id t.timestamps end create_table :playlists_comments do |t| t.integer :playlist_id t.integer :comment_id t.timestamps end create_table :songs_comments do |t| t.integer :song_id t.integer :comment_id t.timestamps end end def self.down drop_table :playlists drop_table :comments drop_table :songs_comments drop_table :users_comments drop_table :users_playlists drop_table :users drop_table :playlists drop_table :songs drop_table :playlists end end

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  • Scheme Homework Assignment

    - by user1704677
    In a course I am taking we recently had to learn the programming language Scheme. I get all of the basics, which is pretty much all that we have gone though. I'm just having trouble learning to think in the different way that Scheme consists of. I was given an assignment and really do not even know how to start. I have sat here for a few hours trying to figure out how to even get started, but I'm kind of stumped. For the record, I'm not asking for the code to solve this problem, but more of some thoughts to get me on the right track. Anyway, here is the gist of the assignment... We are given a list of ten numbers that represent a voter's votes. The numbers are -1, 0 or 1. Then we are given a list of lists of Candidates, with a name and then ten numbers corresponding to that candidate's votes. These numbers are also -1 0 and 1. So for example. '(0 0 0 -1 -1 1 0 1 0 -1) '(Adams 0 1 -1 0 1 1 0 -1 -1 0 0) We are asked to implement a function called best_candidates that will take in a list of numbers (Voter) and a list of lists of Candidates. Then we have to compare the votes of the voter against the list of each candidate and return a list of names with the most common votes. So far, I've come up with a few things. I'm just confused on how I will check the values and retain the name of the voter? I guess I'm still stuck in thinking C/Java and it's making this very tough. Any suggestions to help get me started?

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  • How to stream authenticated content with MediaPlayer on Android

    - by 102790073222983779908
    I've seen quite a few posts askign this question on SO but there doesn't seem to be a definitive answer (or at least an answer I like!) I've got content protected behind basic auth (username/password) -- I can download it fine using the various HTTP download clases but for the life of me I can't sort out how to tell media player to stream it (and provide the authentication). I saw one post that suggested it wasn't possible since the MediaPlayer is all native code and doesn't things like the Authenticator. There are plenty of examples of how to first download to a cached copy and then play that back but....That sort of sucks (and the files maybe 100's of MB's). I saw at least one proposal to download it in smalish chunks and then start & stop the playback (redirecting to the new file) but that sort of sucks also since there would (I presume) be a stutter (I haven't tried it though) The best idea I have at this point is to start downloading to a cache file and then when it's 'full enough' start up playback while I continue to fill the file.... I hope that this works (but again, haven't tried it). Am I missing something obvious? It's so painful to have all the various pieces almost working and I sort of convinced myself that there had to be a way to natively stream protected content (or have it take a already established & qualified InputStream) but it appears no joy. BTW I'm a Mac/iPhone guy and a newb at Android so I'm still fighting a bit of Java learning.... Excuse me if I'm missing somthing obvious. -john

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  • Determining unknown content-types with the Html5 file api

    - by Jesse
    I'm working through a small file upload script (learning experience) and I noticed that when selecting microsoft office related files (.doc or .docx for example) the file objects do not have a type specified: For .doc files I had expected the type to be "application/msword" and along the same train of thought .docx to be "application/vnd.openxmlformats-officedocument.wordprocessingml.document". In the cases when the type cannot be determined is the correct course of action to look at the file extension and match that to the "expected" content / mime type? Sample script: <div id="fileUpload"> <input type="file" id="fileElem" style="display:none;" onchange="handleFiles(this.files)"/> <a href="#" id="fileSelect">Select some files</a> </div> <script type="text/javascript"> var fileSelect = document.getElementById("fileSelect"), fileElem = document.getElementById("fileElem"); fileSelect.addEventListener("click", function (e) { if (fileElem) { fileElem.click(); } e.preventDefault(); }, false); function handleFiles(files) { console.log(files); } </script>

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  • Vector Usage in MPI(C++)

    - by lsk1985
    I am new to MPI programming,stiil learning , i was successful till creating the Derived data-types by defining the structures . Now i want to include Vector in my structure and want to send the data across the Process. for ex: struct Structure{ //Constructor Structure(): X(nodes),mass(nodes),ac(nodes) { //code to calculate the mass and accelerations } //Destructor Structure() {} //Variables double radius; double volume; vector<double> mass; vector<double> area; //and some other variables //Methods to calculate some physical properties Now using MPI i want to sent the data in the structure across the processes. Is it possible for me to create the MPI_type_struct vectors included and send the data? I tried reading through forums, but i am not able to get the clear picture from the responses given there. Hope i would be able to get a clear idea or approach to send the data PS: i can send the data individually , but its an overhead of sending the data using may MPI_Send/Recieve if we consider the domain very large(say 10000*10000)

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  • How can a B-tree node be represented?

    - by chronodekar
    We're learning B-trees in class and have been asked to implement them in code. The teacher has left choice of programming language to us and I want to try and do it in C#. My problem is that the following structure is illegal in C#, unsafe struct BtreeNode { int key_num; // The number of keys in a node int[] key; // Array of keys bool leaf; // Is it a leaf node or not? BtreeNode*[] c; // Pointers to next nodes } Specifically, one is not allowed to create a pointer to point to the structure itself. Is there some work-around or alternate approach I could use? I'm fairly certain that there MUST be a way to do this within the managed code, but I can't figure it out. EDIT: Eric's answer pointed me in the right direction. Here's what I ended up using, class BtreeNode { public List<BtreeNode> children; // The child nodes public static int MinDeg; // The Minimum Degree of the tree public bool IsLeaf { get; set; } // Is the current node a leaf or not? public List<int> key; // The list of keys ... }

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  • Qtimer not timing out QT, C++

    - by realz
    Hi, I am learning C++ and using QT. I have a small program in which I am trying to update the text of the PushButton every second. The label being current time. I have a timer that should time out every second, but seems like it never does. here's the code. Header File #ifndef _HELLOFORM_H #define _HELLOFORM_H #include "ui_HelloForm.h" class HelloForm : public QDialog { public: HelloForm(); virtual ~HelloForm(); public slots: void textChanged(const QString& text); void updateCaption(); private: Ui::HelloForm widget; }; #endif /* _HELLOFORM_H */ CPP file #include "HelloForm.h" #include <QTimer> #include <QtGui/QPushButton> #include <QTime> HelloForm::HelloForm(){ widget.setupUi(this); widget.pushButton->setText(QTime::currentTime().toString()); widget.pushButton->setFont(QFont( "Times", 9, QFont::Bold ) ); QTimer *timer = new QTimer(this); connect(timer, SIGNAL(timeout()), SLOT(updateCaption())); timer->start(1000); connect(widget.pushButton, SIGNAL(clicked()), qApp, SLOT(quit()) ); connect(widget.nameEdit, SIGNAL(textChanged(const QString&)), this, SLOT(textChanged(const QString&))); } HelloForm::~HelloForm() { } void HelloForm::textChanged(const QString& text) { if (0 < text.trimmed().length()) { widget.helloEdit->setText("Hello " + text.trimmed() + "!"); } else { widget.helloEdit->clear(); } } void HelloForm::updateCaption() { QString myVar; myVar = QTime::currentTime().toString(); widget.pushButton->setText(myVar); } Any help will be greatly appreciated... The PushButton's text never changes...

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  • Multi-model form problem

    - by raphael_turtle
    (I'm just learning rails so....) I have a photo model and a gallery model, habtm associations and a join table. I'm making a photo gallery. The gallery page has a title field and description field. User creates gallery title, then goes to the photo page and checkboxes each image they want in that gallery. I get the error "undefined method `to_i' for ["1", {"title"="1"}]:Array" when trying to save/update a photo with a gallery title(with the checkbox) <% form_for @photo, :html => {:multipart => true } do |f| %> <%= f.error_messages %> <p> <%= f.label :title %> <%= f.text_field :title %> </p> <p> <%= f.label :description %> <%= f.text_area :description %> </p> <p> <%= f.label :image %> <%= f.file_field :image %> </p> <% for gallery in @photo.galleries %> <% fields_for "painting[gallery_attributes][]", gallery do |g| %> <div> <%= g.check_box :title %> <%= gallery.title %> </div> <% end %> <% end %> <p><%= submit_tag 'Update' %></p> <% end %> How much of this is horribly wrong? Can someone point me in the right direction?, I can't find any tutorials relating to this for 2.3 and above.

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  • OOP + MVC advice on Member Controller

    - by dan727
    Hi, I am trying to follow good practices as much as possible while I'm learning using OOP in an MVC structure, so i'm turning to you guys for a bit of advice on something which is bothering me a little here. I am writing a site where I will have a number of different forms for members to fill in (mainly data about themselves), so i've decided to set up a Member controller where all of the forms relating to the member are represented as individual methods. This includes login/logout methods, as well as editing profile data etc. In addition to these methods, i also have a method to generate the member's control panel widget, which is a constant on every page on the site while the member is logged in. The only thing is, all of the other methods in this controller all have the same dependencies and form templates, so it would be great to generate all this in the constructor, but as the control_panel method does not have the same dependencies etc, I cannot use the constructor for this purpose, and instead I have to redeclare the dependencies and same template snippets in each method. This obviously isn't ideal and doesn't follow DRY principle, but I'm wondering what I should do with the control_panel method, as it is related to the member and that's why I put it in that controller in the first place. Am I just over-complicating things here and does it make sense to just move the control_panel method into a simple helper class? Here are the basic methods of the controller: class Member_Controller extends Website_Controller { public function __construct() { parent::__construct(); if (request::is_ajax()) { $this->auto_render = FALSE; // disable auto render } } public static function control_panel() { //load control panel view $panel = new View('user/control_panel'); return $panel; } public function login() { } public function register() { } public function profile() { } public function household() { } public function edit_profile() { } public function logout() { } }

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  • Choose 'better' or more familiar technologies for a new project?

    - by John
    I am looking to start work on a brand-new project, something I've been thinking about for a while as my first independent sellable project. It's broadly speaking a web-based service application, and my first choice, server-language is quite easy... I know Java pretty well from working on Java web-apps in the past. However my experience doing web-apps involved JSP, Servlets and JSTL... I know the ideas behind newer technologies like Hibernate/Spring but have never used them. So we wrote our own DAOs, handled AJAX by writing special mini-JSP pages that generated XML/JSON pages, etc. I'm not hugely into the idea that Spring/Hibernate are the 'only' or 'right' way to do any Java web-project, but they are widely used. On the other hand, not only would trying to learn these increase initial development time, but I'd be using my learning attempts to build a production system. I remember one of Joel's early articles said (I'll paraphrase since I can't find it) "regardless what's cool, always use the technologies that the lead developer (or dev team?) knows best" I wondered what people thought about that? ps: should this be CW?

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  • How to approach socket programming between C# -> Java (Android)

    - by Alex
    I've recently knocked up a server/client app for Windows & Android that allows one to send a file from Windows to an android phone over a socket connection. It works great for a single file but trying to send multiple files over in a single stream is causing me problems. I've also realised that aside from the binary data, I will need to send messages over the socket to indicate error states and other application messages. I have little experience with network programming and and wondering what is the best way forward. Basically the C# server side of the app just goes into a listening state and uses Socket.SendFile to transmit the file. On Android I use the standard Java Socket.getInputStream() to receive the file. That works great for a single file transfer, but how should I handle multiple files and error/messaging information? Do I need to use a different socket for each file? Should I be using a higher level framework to handle this or can I send everything over the single socket? Any other suggestions for frameworks or learning materials?

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  • How can I be a Guru? Is it possible? [closed]

    - by Kev
    Before 1999, I heard about computer. But, I don't know what it look like. TV? Maybe! Before 2001, I only saw it in book. It looks like a TV. Before 2005, I touched it in reality. It still looks like a TV + Black Box. In 2005, I entered university. I had a cource about Mathematica.I loved programming since then. In 2006, I owned a computer. I was coding C every day. if...else..., for..., while..., switch... entered my life. Since 2007, I have learned Data Structures, Algorithms...Then, C#, Java, Python, HTML/CSS/JavaScript, F#... A lot of languages. I'm still learning new lang. Unfortunately, I only know syntax! I'm always a novice(??)! I know some guru start programming at age of 8 or 12. I admire these gurus who are compiler writers, language designers, architecture designers, Linux hackers... Is it possible to become a guru like me. If possible, how? what should I do now? Any advice? Thank you very much.

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  • Calling a constructor from method within the same class

    - by Nathan
    I'm new to java and I'm learning about creating object classes. One of my homework assignment requires that I call the constructor at least once within a method of the same object class. I'm getting an error that says The method DoubleMatrix(double[][]) is undefined for the type DoubleMatrix Here's my constructor: public DoubleMatrix(double[][] tempArray) { // Declaration int flag = 0; int cnt; // Statement // check to see if doubArray isn't null and has more than 0 rows if(tempArray == null || tempArray.length < 0) { flag++; } // check to see if each row has the same length if(flag == 0) { for(cnt = 0; cnt <= tempArray.length - 1 || flag != 1; cnt++) { if(tempArray[cnt + 1].length != tempArray[0].length) { flag++; } } } else if(flag == 1) { makeDoubMatrix(1, 1);// call makeDoubMatrix method } }// end constructor 2 Here's the method where I try and call the constructor: public double[][] addMatrix(double[][] tempDoub) { // Declaration double[][] newMatrix; int rCnt, cCnt; //Statement // checking to see if both are of same dimension if(doubMatrix.length == tempDoub.length && doubMatrix[0].length == tempDoub[0].length) { newMatrix = new double[doubMatrix.length][doubMatrix[0].length]; // for loop to add matrix to a new one for(rCnt = 0; rCnt <= doubMatrix.length; rCnt++) { for(cCnt = 0; cCnt <= doubMatrix.length; cCnt++) { newMatrix[rCnt][cCnt] = doubMatrix[rCnt][cCnt] + tempDoub[rCnt][cCnt]; } } } else { newMatrix = new double[0][0]; DoubleMatrix(newMatrix) } return newMatrix; }// end addMatrix method Can someone point me to the right direction and explain why I'm getting an error?

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  • C function prototype: void f(). Is it recommended?

    - by ycalleecharan
    Hi, I'm learning C and I saw in a book that a function prototype has the form void f() and in the function declaration or in the calling function, the f function takes arguments. Thus In the function declaration we have something like void f(long double y[], long double A) and in the calling function is f(y, A). The function is doing operations on the array y i.e. when the function is called, some elements in the array y are changing. A is just a constant numerical value that doesn't change. I have two questions: If defining the function prototype at the top in the program as void f() a good practice? Or is it better to put it as void f(long double y[], long double A) as in the function declaration? The called function f is changing elements in the array y. Is void the right return type? The program is working fine as such with the void as described. Or should I change all my "voids" to "long double". I'm working with long double as I need as much precision as possible though on my machine both double and long double gives me 15 precision digits. Thanks a lot

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  • How do I compare 2 fields and return the lowest value of each record?

    - by BigRob
    I'm slowly learning access to make a database of products and suppliers for my parents' business. What i've got is a table of products indexed by our product reference and 2 more tables for 2 different suppliers that contains the suppliers product reference and price that links with our reference. I've made a query that performs a left outer join such that it returns a table of our products with each supplier's reference and price, i.e: Ref | Product Name | Supplier 1 Ref | Supplier 1 Price | Supplier 2 Ref | Supplier 2 Price Here's the query I used: SELECT Catalog.Ref, Catalog.[Product Name], Catalog.Price, [D Products].[Supplier Ref], [D Products].Cost, [GS Products].[Supplier Ref], [GS Products].Cost FROM ([Catalog] LEFT JOIN [D Products] ON Catalog.Ref = [D Products].Ref) LEFT JOIN [GS Products] ON Catalog.Ref = [GS Products].Ref; Not all products are available from both suppliers, hence the outer join. What I want to do (with a query?) is to take the table produced by the query above and simply show the product reference, cheapest supplier reference and cheapest supplier price, i.e: Ref | Cheapest Suppplier Ref | Cheapest Supplier Price Unfortunately my SQL knowledge isn't quite good enough to figure this out, but if anyone can help i'd really appreciate it. Thanks, Rob

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  • Java PropertyChangeListener

    - by Laphroaig
    Hi, i'm trying to figure out how to listen a property change on another class. this is my code: class with the property to listen: public class ClassWithProperty { private PropertyChangeSupport changes = new PropertyChangeSupport(this); private int usersOnline; public int getUsersOnline() { return usersOnline; } public ClassWithProperty() { usersOnline = 0; while (usersOnline<10) { changes.firePropertyChange("usersOnline", usersOnline, usersOnline++); } } public void addPropertyChangeListener( PropertyChangeListener l) { changes.addPropertyChangeListener(l); } public void removePropertyChangeListener( PropertyChangeListener l) { changes.removePropertyChangeListener(l); } } class where i need to know when the property change: public class Main { private static ClassWithProperty test; public static void main(String[] args) { test = new ClassWithProperty(); test.addPropertyChangeListener(listen()); } private static PropertyChangeListener listen() { System.out.println(test.getUsersOnline()); return null; } } I have the event fired only the last time (usersOnline=10). Sorry if it can be a stupid question, i'm learning now java and can't find a solution.

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  • Is this function thread-safe?

    - by kiddo
    Hello all,I am learning multi-threading and for the sake of understanding I have wriiten a small function using multithreading...it works fine.But I just want to know if that thread is safe to use,did I followed the correct rule. void CThreadingEx4Dlg::OnBnClickedOk() { //in thread1 100 elements are copied to myShiftArray(which is a CStringArray) thread1 = AfxBeginThread((AFX_THREADPROC)MyThreadFunction1,this); WaitForSingleObject(thread1->m_hThread,INFINITE); //thread2 waits for thread1 to finish because thread2 is going to make use of myShiftArray(in which thread1 processes it first) thread2 = AfxBeginThread((AFX_THREADPROC)MyThreadFunction2,this); thread3 = AfxBeginThread((AFX_THREADPROC)MyThreadFunction3,this); } UINT MyThreadFunction1(LPARAM lparam) { CThreadingEx4Dlg* pthis = (CThreadingEx4Dlg*)lparam; pthis->MyFunction(0,100); return 0; } UINT MyThreadFunction2(LPARAM lparam) { CThreadingEx4Dlg* pthis = (CThreadingEx4Dlg*)lparam; pthis->MyCommonFunction(0,20); return 0; } UINT MyThreadFunction3(LPARAM lparam) { CThreadingEx4Dlg* pthis = (CThreadingEx4Dlg*)lparam; WaitForSingleObject(pthis->thread3->m_hThread,INFINITE); //here thread3 waits for thread 2 to finish so that thread can continue pthis->MyCommonFunction(21,40); return 0; } void CThreadingEx4Dlg::MyFunction(int minCount,int maxCount) { for(int i=minCount;i<maxCount;i++) { //assume myArray is a CStringArray and it has 100 elemnts added to it. //myShiftArray is a CStringArray -public to the class CString temp; temp = myArray.GetAt(i); myShiftArray.Add(temp); } } void CThreadingEx4Dlg::MyCommonFunction(int min,int max) { for(int i = min;i < max;i++) { CSingleLock myLock(&myCS,TRUE); CString temp; temp = myShiftArray.GetAt(i); //threadArray is CStringArray-public to the class threadArray.Add(temp); } myEvent.PulseEvent(); }

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  • Can a pc with a 1.2 ghz dual core run VS 2013? [on hold]

    - by moo2
    Edit: This question is about a tool used for programming, Microsoft Visual Studio 2013. I already read the minimum requirements for VS 2013 before I posted or I wouldn't have asked the question. I searched on the web for an answer for a few hours before posting. Why should I go out and spend $400 on a laptop if I can spend less than $100 and use it to learn how to program? In the context of the question it is clear I was not asking for advice on what laptop to buy and it was also clear I was not asking for someone to walk me through the system requirements of VS 2013. This is a vast community and I was wondering if someone in this vast community would have experience in dealing with my question. In other words has anyone ever tried anything like it? If I had an old computer sitting around I would have tested it. At the moment all I have is a friend's Chromebook I'm borrowing. End Edit. I know the requirements for Microsoft Visual Studio 2013 state 1.6 ghz processor. I'm looking at getting a laptop for school and I found one that is old but cheap and would work for college. The Dell D430 I'm looking at getting has a 1.2ghz Core 2 Duo CPU, 80GB HD, 2GB RAM, and Windows 7 Home Premium. It's refurbished. I can get it for less than most phone's cost and from a Microsoft Authorized Refurbisher. I know it's not a skyrim rig but it's lightweight and can handle being a college laptop and doing word processing. Would Visual Studio 2013 run at all? If it is slower I'm not concerned. I just want to know if it would work and compile my assignments and run them? I'd be using this laptop for doing assignments and learning programming languages not for coding the next social media sensation.

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