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• Dealing with infinite loops when constructing states for LR(1) parsing

  - by Bruce

  I'm currently constructing LR(1) states from the following grammar. S->AS S->c A->aA A->b where A,S are nonterminals and a,b,c are terminals. This is the construction of I0 I0: S' -> .S, epsilon --------------- S -> .AS, epsilon S -> .c, epsilon --------------- S -> .AS, a S -> .c, c A -> .aA, a A -> .b, b And I1. From S, I1: S' -> S., epsilon //DONE And so on. But when I get to constructing I4... From a, I4: A -> a.A, a ----------- A -> .aA, a A -> .b, b The problem is A - .aA When I attempt to construct the next state from a, I'm going to once again get the exact same content of I4, and this continues infinitely. A similar loop occurs with S -> .AS So, what am I doing wrong? There has to be some detail that I'm missing, but I've browsed my notes and my book and either can't find or just don't understand what's wrong here. Any help?

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• Deploy to web container, bundle web container or embed web container...

  - by Jason

  I am developing an application that needs to be as simple as possible to install for the end user. While the end users will likely be experience Linux users (or sales engineers), they don't really know anything about Tomcat, Jetty, etc, nor do I think they should. So I see 3 ways to deploy our applications. I should also state that this is the first app that I have had to deploy that had a web interface, so I haven't really faced this question before. First is to deploy the application into an existing web container. Since we only deploy to Suse or RedHat this seems easy enough to do. However, we're not big on the idea of multiple apps running in one web container. It makes it harder to take down just one app. The next option is to just bundle Tomcat or Jetty and have the startup/shutdown scripts launch our bundled web container. Or 3rd, embed.. This will probably provide the same user experience as the second option. I'm curious what others do when faced with this problem to make it as fool proof as possible on the end user. I've almost ruled out deploying into an existing web container as we often like to set per application resource limits and CPU affinity, which I believe would affect all apps deployed into a web container/app server and not just a specific application. Thank you.

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• CoreData is saving model without the save: method being called

  - by chris

  I have a list of items with a plus button in the navigation bar that opens up a modal window containing a table of the models attributes, that displays a form when the table items are clicked (pretty standard form style). For some reason if I click the plus button to open the form to create a new model, then immediately click the done button, the person model is saved. The action linked to the done button does nothing but call on a delegate method notifying the personListViewController to close the window. The apple docs do state that the model is not saved after calling the insertNewObjectForEntityName: ... Simply creating a managed object does not cause it to be saved to a persistent store. The managed object context acts as a scratchpad. I am at a lost to why this is happening, but every time I click the done button I have a new blank item in the original tableView. I am using SDK v3.1.3 // PersonListViewController - open modal window - (void)addPerson { // Load the new form PersonNewViewController *newController = [[PersonNewViewController alloc] init]; newController.modalFormDelegate = self; [self presentModalViewController:newController animated:YES]; [newController release]; } // PersonFormViewController - (void)viewDidLoad { [super viewDidLoad]; if ( person == nil ) { MyAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate]; self.person = [NSEntityDescription insertNewObjectForEntityForName:@"Person" inManagedObjectContext:appDelegate.managedObjectContext]; } ... UIBarButtonItem *doneButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(done)]; self.navigationItem.rightBarButtonItem = doneButton; [doneButton release]; } - (IBAction) done { [self.modalFormDelegate didCancel]; } // delegate method in the original listViewController - (void) didCancel { [self dismissModalViewControllerAnimated:YES]; }

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• How to populate a dropdownlist with json data in jquery?

  - by Pandiya Chendur

  I am developing a country state cascading dropdown list... I returned json result based on countryId but i dont know how to populate/fill it in a new dropdown listbox... Here is what i am using, function getstate(countryId) { $.ajax({ type: "POST", url: "Reg_Form.aspx/Getstates", data: "{'countryId':" + (countryId) + "}", contentType: "application/json; charset=utf-8", global: false, async: false, dataType: "json", success: function(jsonObj) { alert(jsonObj.d); } }); return false; } And alert gave this, {"Table" : [{"stateid" : "2","statename" : "Tamilnadu"}, {"stateid" : "3","statename" : "Karnataka"}, {"stateid" : "4","statename" : "Andaman and Nicobar"}, {"stateid" : "5","statename" : "Andhra Pradesh"}, {"stateid" : "6","statename" : "Arunachal Pradesh"}]} And my aspx page has this is, <td> <asp:DropDownList ID="DLCountry" runat="server" CssClass="dropDownListSkin" onchange="return getstate(this.value);"> </asp:DropDownList> </td> <td> <asp:DropDownList ID="DLState" runat="server" CssClass="dropDownListSkin"> </asp:DropDownList> </td> Any suggestion how to fill it DLState dropdown...

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• Modules vs. Classes and their influence on descendants of ActiveRecord::Base

  - by Chris

  Here's a Ruby OO head scratcher for ya, brought about by this Rails scenario: class Product < ActiveRecord::Base has_many(:prices) # define private helper methods end module PrintProduct attr_accessor(:isbn) # override methods in ActiveRecord::Base end class Book < Product include PrintProduct end Product is the base class of all products. Books are kept in the products table via STI. The PrintProduct module brings some common behavior and state to descendants of Product. Book is used inside fields_for blocks in views. This works for me, but I found some odd behavior: After form submission, inside my controller, if I call a method on a book that is defined in PrintProduct, and that method calls a helper method defined in Product, which in turn calls the prices method defined by has_many, I'll get an error complaining that Book#prices is not found. Why is that? Book is a direct descendant of Product! More interesting is the following.. As I developed this hierarchy PrintProduct started to become more of an abstract ActiveRecord::Base, so I thought it prudent to redefine everything as such: class Product < ActiveRecord::Base end class PrintProduct < Product end class Book < PrintProduct end All method definitions, etc. are the same. In this case, however, my web form won't load because the attributes defined by attr_accessor (which are "virtual attributes" referenced by the form but not persisted in the DB) aren't found. I'll get an error saying that there is no method Book#isbn. Why is that?? I can't see a reason why the attr_accessor attributes are not found inside my form's fields_for block when PrintProduct is a class, but they are found when PrintProduct is a Module. Any insight would be appreciated. I'm dying to know why these errors are occurring!

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• Open closed prinicple, problem

  - by Marcus

  Hi, I'm trying to apply OCP to a code snippet I have that in it's current state is really smelly, but I feel I'm not getting all the way to the end. Current code: public abstract class SomeObject {} public class SpecificObject1 : SomeObject {} public class SpecificObject2 : SomeObject {} // Smelly code public class Model { public void Store(SomeObject someObject) { if (someObject is SpecificObject1) {} else if (someObject is SpecificObject2) {} } } That is really ugly, my new approach looks like this: // No so smelly code public class Model { public void Store(SomeObject someObject) { throw new Expception("Not allowed!"); } public void Store(SpecificObject1 someObject) {} public void Store(SpecificObject2 someObject) {} } When a new SomeObject type comes along I must implement how that specific object is stored, this will break OCP cause I need to alter the Model-class. To move the store logic to SomeObject also feels wrong cause then I will violate SRP (?), becuase in this case the SomeObject is almost like a DTO, it's resposibility it not how to know to store itself. If a new implementation to SomeObject comes along who's store implementation is missing I will get a runtime error due to exception in Store method in Model class, it also feels like a code smell. This is because calling code will in the form of IEnumerable<SomeObject> sequence; I will not know the specific types of the sequence objects. I can't seem to grasp the OCP-concept. Anyone has any concrete examples or links that is a bit more than just some Car/Fruit example?

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• WPF - Extend ListView with checkable AND selectable ListViewItems

  - by Marks

  Hi there. I already read many examples on extending ListViews with checkboxes bound with IsSelected. But I want something more. I want a seperation between the checked and selected state, so i get a ListBox that has a single selected item, but can have multiple checked items. Unfortunately ListViewItem does not have a property for checked and I dont see a possibility to get the ListView to work with a custom CheckableListViewItem. Of course i could use a List of objects with a checked property as ItemSource, but I dont think thats a good way to go. Checked or not is a matter of the list or item-container, not of the object listed in it. Beside that I dont want all my classes like user, role, group to have counterparts like checkableUser, checkableRole and checkableGroup. The behaviour i want can be easyly accomblished for the UI with a <DataTemplate x:Key="CheckBoxCell"> <StackPanel Orientation="Horizontal"> <CheckBox /> </StackPanel> </DataTemplate> and a <GridViewColumn CellTemplate="{StaticResource CheckBoxCell}" Width="30"/> But without a binding on the checkbox i cant check if it is checked or not. Is there any way to accomplish something like that? The perfect solution for me would be to have listView1.SelectedItem, listView1.CheckedItems and maybe a listView1.UncheckedItems and of course listView1.CheckItem and listView1.UncheckItem. Thanks for any help.

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• Simple question about the lunarlander example.

  - by Smills

  I am basing my game off the lunarlander example. This is the run loop I am using (very similar to what is used in lunarlander). I am getting considerable performance issues associated with my drawing, even if I draw almost nothing. I noticed the below method. Why is the canvas being created and set to null each cycle? @Override public void run() { while (mRun) { Canvas c = null; try { c = mSurfaceHolder.lockCanvas();//null synchronized (mSurfaceHolder) { updatePhysics(); doDraw(c); } } finally { // do this in a finally so that if an exception is thrown // during the above, we don't leave the Surface in an // inconsistent state if (c != null) { mSurfaceHolder.unlockCanvasAndPost(c); } } } } Most of the times I have read anything about canvases it is more along the lines of: mField = new Bitmap(...dimensions...); Canvas c = new Canvas(mField); My question is: why is Google's example done that way (null canvas), what are the benefits of this, and is there a faster way to do it?

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• Load In and Animate content

  - by crozer

  Hello, I have a little issue concerning an animation-effect which loads a certain div into the body of the site. Let me be more precise: I have a div with the id 'contact': <div id="contact">content</div> The jquery code loads the contents within that div, when I press the link with the id 'ajax_contact': <a href="#" id="ajax_contact">link</a>. The code is working perfectly. However, I want #contact to be HIDDEN when the site loads, i.e. the default state must be non-visible. Only when the user clicks the link #ajax_contact, the div must appear. Please have a look at the jquery code: $(document).ready(function() { var hash = window.location.hash.substr(1); var href = $('#ajax_contact').each(function(){ var href = $(this).attr('href'); if(hash==href.substr(0,href.length-5)){ var toLoad = hash+'.html #contact'; $('#contact').load(toLoad) } }); $('#ajax_contact').click(function(){ var toLoad = $(this).attr('href')+' #contact'; $('#contact').hide('fast',loadContent); $('#load').remove(); $('body').append('<span id="load">LOADING...</span>'); $('#load').fadeIn('normal'); window.location.hash = $(this).attr('href').substr(0,$(this).attr('href').length-5); function loadContent() { $('#contact').load(toLoad,'',showNewContent()) } function showNewContent() { $('#contact').show('normal',hideLoader()); } function hideLoader() { $('#load').fadeOut('normal'); } return false; }); }); I am not sure whether I must change something inside the HTML, but I believe the key is inside the jquery-code. I also tried giving the #contact a CSS style of visible:none, yet this loops and makes the jquery impossible to load the #contact in. I hope I've explained myself well; thank you very much in advance. Chris

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• NSOutlineView not redrawing

  - by Septih

  Hello, I have an NSOutlineView with checkboxes. I have the checkbox state bound to a node item with the key shouldBeCopied. In the node item I have the getters and setters like so: -(BOOL)shouldBeCopied { if([[self parent] shouldBeCopied]) return YES; return shouldBeCopied; } -(void)setShouldBeCopied:(BOOL)value { shouldBeCopied = value; if(value && [[self children] count] > 0) [[self delegate] reloadData]; } The idea here is that if the parent is checked, so should the children. The problem I'm having is that when I check the parent, it does not update that view of the children if they are already expanded. I can understand that it should not be updated by the bindings because i'm not actually changing the value. But should reloadData not cause the bindings to re-get the value, thus calling -shouldBeCopied for the children? I have tried a few other things such as -setNeedsDisplay and -reloadItem:nil reloadChildren:YES but none work. I've noticed that the display gets refreshed when I swap to xcode and then back again and that's all I want, so how do I get it to behave that way?

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• Conversion failed when converting datetime from character string

  - by salvationishere

  I am developing a C# VS 2008 / SQL Server 2005 Express website application. I have tried some of the fixes for this problem but my call stack differs from others. And these fixes did not fix my problem. What steps can I take to troubleshoot this? Here is my error: System.Data.SqlClient.SqlException was caught Message="Conversion failed when converting datetime from character string." Source=".Net SqlClient Data Provider" ErrorCode=-2146232060 LineNumber=10 Number=241 Procedure="AppendDataCT" Server="\\\\.\\pipe\\772EF469-84F1-43\\tsql\\query" State=1 StackTrace: at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString) at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result) at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(DbAsyncResult result, String methodName, Boolean sendToPipe) at System.Data.SqlClient.SqlCommand.ExecuteNonQuery() at ADONET_namespace.ADONET_methods.AppendDataCT(DataTable dt, Dictionary`2 dic) in c:\Documents and Settings\Admin\My Documents\Visual Studio 2008\WebSites\Jerry\App_Code\ADONET methods.cs:line 102 And here is the related code. When I debugged this code, "dic" only looped through the 3 column names, but did not look into row values which are stored in "dt", the Data Table. public static string AppendDataCT(DataTable dt, Dictionary<string, string> dic) { if (dic.Count != 3) throw new ArgumentOutOfRangeException("dic can only have 3 parameters"); string connString = ConfigurationManager.ConnectionStrings["AW3_string"].ConnectionString; string errorMsg; try { using (SqlConnection conn2 = new SqlConnection(connString)) { using (SqlCommand cmd = conn2.CreateCommand()) { cmd.CommandText = "dbo.AppendDataCT"; cmd.CommandType = CommandType.StoredProcedure; cmd.Connection = conn2; foreach (string s in dic.Keys) { SqlParameter p = cmd.Parameters.AddWithValue(s, dic[s]); p.SqlDbType = SqlDbType.VarChar; } conn2.Open(); cmd.ExecuteNonQuery(); conn2.Close(); errorMsg = "The Person.ContactType table was successfully updated!"; } } }

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• Should we retire the term "Context"?

  - by MrGumbe

  I'm not sure if there is a more abused term in the world of programming than "Context." A word that has a very clear meaning in the English language has somehow morphed into a hot mess in software development, where the definition where the connotation can be completely different based on what library you happen to be developing in. Tomcat uses the word context to mean the configuration of a web application. Java applets, on the other hand, use an AppletContext to define attributes of the browser and HTML tag that launched it, but the BeanContext is defined as a container. ASP.NET uses the HttpContext object as a grab bag of state - containing information about the current request / response, session, user, server, and application objects. Context Oriented Programming defines the term as "Any information which is computationally accessible may form part of the context upon which behavioral variations depend," which I translate as "anything in the world." The innards of the Windows OS uses the CONTEXT structure to define properties about the hardware environment. The .NET installation classes, however, use the InstallContext property to represent the command line arguments entered to the installation class. The above doesn't even touch how all of us non-framework developers have used the term. I've seen plenty of developers fall into the subconscious trap of "I can't think of anything else to call this class, so I'll name it 'WidgetContext.'" Do you all agree that before naming our class a "Context," we may want to first consider some more descriptive terms? "Environment", "Configuraton", and "ExecutionState" come readily to mind.

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• Could someone explain gtk2hs drag and drop to me, the listDND.hs demo just isn't doing it for me?

  - by Tom Carstens

  As the title says, I just don't get DND (or rather I understand the concept and I understand the order of callbacks, I just don't understand how to setup DND for actual usage.) I'd like to say that I've done DND stuff before in C, but considering I never really got that working... So I'm trying (and mostly succeeding, save DND) to write a text editor (using gtksourceview, because it has built in code highlighting.) Reasons are below if you want them. Anyways, there's not really a good DND demo or tutorial available for gtk2hs (listDND.hs just doesn't translate well in my head.) So what I'm asking is for code that demonstrates simple DND on a window widget (for example.) Ideally, it should accept drops from other windows (such as Thunar) and print out the information in string form. I think I can take it from there... Reasons: I'm running a fairly light weight setup, dwm and a few gtk+2 programs. I really don't want to have to pull in gtk+3 to get the current gedit from the repos (Arch Linux.) Currently, I'm using geany for all of my text editing needs, however, geany is a bit heavy for editing config files. Further, geany doesn't care for my terminal of choice (st;) so I don't even get the benefit of using it as an IDE. Meaning I'd like a lightweight text editor with syntax highlighting. I could configure emacs or vim or something, but that seems to me to be more of a hack then a proper solution. Thus my project was born. It's mostly working (aside from DND, all that's left is proper multi-tab support.) Admittedly, I could probably work this out if I wrote it in C, but there isn't that much state in a text editor so Haskell's been working fine with almost no need for mutable variables.

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• How to work with CTE. There is some error related to anchor.

  - by Shantanu Gupta

  I am creating a hierarchy representaion of a column. But an error occurs Details are Msg 240, Level 16, State 1, Line 1 Types don't match between the anchor and the recursive part in column "DISPLAY" of recursive query "CTE". I know there is some typecasting error. But I dont know how to remove error. Please just dont only sort out my error. I need explanation why this error is coming. When this error occurs. I am trying to sort table on the basis of sort col that i m introducing. I want to add '-' at every level and want to sort accordingly. Please help WITH CTE (PK_CATEGORY_ID, [DESCRIPTION], FK_CATEGORY_ID, DISPLAY, SORT, DEPTH) AS ( SELECT PK_CATEGORY_ID, [DESCRIPTION], FK_CATEGORY_ID, '-' AS DISPLAY, '--' AS SORT, 0 AS DEPTH FROM dbo.L_CATEGORY_TYPE WHERE FK_CATEGORY_ID IS NULL UNION ALL SELECT T.PK_CATEGORY_ID, T.[DESCRIPTION], T.FK_CATEGORY_ID, CAST(DISPLAY+T.[DESCRIPTION] AS VARCHAR(1000)), '--' AS SORT, C.DEPTH +1 FROM dbo.L_CATEGORY_TYPE T JOIN CTE C ON C.PK_CATEGORY_ID = T.FK_CATEGORY_ID --SELECT T.PK_CATEGORY_ID, C.SORT+T.[DESCRIPTION], T.FK_CATEGORY_ID --, CAST('--' + C.SORT AS VARCHAR(1000)) AS SORT, CAST(DEPTH +1 AS INT) AS DEPTH --FROM dbo.L_CATEGORY_TYPE T JOIN CTE C ON C.FK_CATEGORY_ID = T.PK_CATEGORY_ID ) SELECT PK_CATEGORY_ID, [DESCRIPTION], FK_CATEGORY_ID, DISPLAY, SORT, DEPTH FROM CTE ORDER BY SORT

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• Import CSV to class structure as the user defines

  - by Assimilater

  I have a contact manager program and I would like to offer the feature to import csv files. The problem is that different data sources order the fields in different ways. I thought of programming an interface for the user to tell it the field order and how to handle exceptions. Here is an example line in one of many possible field orders: "ID#","Name","Rank","Address1","Address2","City","State","Country","Zip","Phone#","Email","Join Date","Sponsor ID","Sponsor Name" "Z1234","Call, Anson","STU","1234 E. 6578 S.","","Somecity","TX","United States","012345","000-000-0000","[email protected]","5/24/2010","z12343","Quantum Independence" Notice that in one data field "Name" there is a comma to separate last name and first name and in another there is not. My plan is to have a line for each field (ie ID, Name, City etc.) and a statement "import to" and list box with options like: Don't Import, BusinessJoin Date, First Name, Zip and the program recognizes those as properties of an object... I'd also like the user to be able to record preset field orders so they can re-use them for csv files from the same download source. Then I also need it to check if a record all ready exists (is there a record for Anson Call all ready?) and allow the user to tell it what to do if there is a record (ie mailing address may have changes, so if that field is filled overwrite it, or this mailing address is invalid, leave the current data untouched for this person, overwrite the rest). While I'm capable of coding this...i'm not very excited about it and I'm wondering if there's a tool or set of tools out there to all ready perform most of this functionality... I hope this makes sense...

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• Implementing a scrabble trainer (cheater)

  - by bstullkid

  Hello, I've recently been playing alot of online scrabble so I decided to make a program that quickly searches through a dictionary of 200,000+ words with an input of up to any 26 letters. My first attempt was fail as it took a while when you input 8 or more letters (just a basic look through dictionary and cancel out a letter if its found kind of thing), so I made a tree like structure containing only an array of 26 of the same structure and a flag to indicate the end of a word, doing that It can output all possible words in under a second even with an input of 26 characters. But it seems that when I input 12 or more letters with some of the same characters repeated i get duplicates; can anyone see why I would be getting duplicates with this code? (ill post my program at the bottom) Also, the next step once the duplicates are weeded out is to actually be able to input the letters on the game board and then have it calculate the best word you can make on a given board. I am having trouble trying to figure out a good algorithm that can analyze a scrabble board and an input of letters and output a result; the possible words that could be made I have no problem with but actually checking a board efficiently (ie can this word fit here, or here etc... without creating a non dictionary word in the process on some other string of letters) Anyone have a idea for an approach at that? (given a scrabble board, and an input of 7 letters, find all possible valid words or word sets that you can make) lol crap i forgot to email myself the code from my other computer thats in another state... ill post it on monday when I get back there! btw the dictionary im using is sowpods (http://www.calvin.edu/~rpruim/scrabble/ospd3.txt)

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• How Many States Does an Activity Have?

  - by Android Eve

  The Activity lifecycle section in the Application Fundamentals tutorial states that there are 3 states: An activity has essentially three states: (1. active/running 2. paused 3. stopped) But then as I continued reading the actual Activity class documentation, the Activity Lifecycle section states that there are 4 state: An activity has essentially four states: (1. active/running 2. paused 3. stopped 4. "dropped"?) Both sources (on the same website) agree about the first 3, but the 4th one is only mentioned in the class documentation and is unnamed. So, are there really 4 states or only 3? If there are 4, what is the name of the 4th one? Please help me understand this discrepancy. Also, highlighted colored blocks in this beautiful and very informative flowchart don't seem to correspond to the states. Where, in the flowchart, would you mark the 3 or 4 states?

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• close file with fopen() but file still in use

  - by Marco

  Hi all, I've got a problem with deleting/overwriting a file using my program which is also being used(read) by my program. The problem seems to be that because of the fact my program is reading data from the file (output.txt) it puts the file in a 'in use' state which makes it impossible to delete or overwrite the file. I don't understand why the file stays 'in use' because I close the file after use with fclose(); this is my code: bool bBool = true while(bBool){ //Run myprogram.exe tot generate (a new) output.txt //Create file pointer and open file FILE* pInputFile = NULL; pInputFile = fopen("output.txt", "r"); // //then I do some reading using fscanf() // //And when I'm done reading I close the file using fclose() fclose(pInputFile); //The next step is deleting the output.txt if( remove( "output.txt" ) == -1 ){ //ERROR }else{ //Succesfull } } I use fclose() to close the file but the file remains in use by my program until my program is totally shut down. What is the solution to free the file so it can be deleted/overwrited? In reality my code isn't a loop without an end ; ) Thanks in advance! Marco

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• Converting "A* Search" code from C++ to Java [on hold]

  - by mr5

  Updated! I get this code from this site It's A* Search Algorithm(finding shortest path with heuristics) I modify most of variable names and some if conditions from the original version to satisfy my syntactic taste. It works in C++ (as I can't see any trouble with it) but fails in Java version. Java Code: String findPath(int startX, int startY, int finishX, int finishY) { @SuppressWarnings("unchecked") LinkedList<Node>[] nodeList = (LinkedList<Node>[]) new LinkedList<?>[2]; nodeList[0] = new LinkedList<Node>(); nodeList[1] = new LinkedList<Node>(); Node n0; Node m0; int nlIndex = 0; // queueList index // reset the node maps for(int y = 0;y < ROW_COUNT; ++y) { for(int x = 0;x < COL_COUNT; ++x) { close_nodes_map[y][x] = 0; open_nodes_map[y][x] = 0; } } // create the start node and push into list of open nodes n0 = new Node( startX, startY, 0, 0 ); n0.updatePriority( finishX, finishY ); nodeList[nlIndex].push( n0 ); open_nodes_map[startY][startX] = n0.getPriority(); // mark it on the open nodes map // A* search while( !nodeList[nlIndex].isEmpty() ) { LinkedList<Node> pq = nodeList[nlIndex]; // get the current node w/ the highest priority // from the list of open nodes n0 = new Node( pq.peek().getX(), pq.peek().getY(), pq.peek().getIterCount(), pq.peek().getPriority()); int x = n0.getX(); int y = n0.getY(); nodeList[nlIndex].pop(); // remove the node from the open list open_nodes_map[y][x] = 0; // mark it on the closed nodes map close_nodes_map[y][x] = 1; // quit searching when the goal state is reached //if((*n0).estimate(finishX, finishY) == 0) if( x == finishX && y == finishY ) { // generate the path from finish to start // by following the directions String path = ""; while( !( x == startX && y == startY) ) { int j = dir_map[y][x]; int c = '0' + ( j + Node.DIRECTION_COUNT / 2 ) % Node.DIRECTION_COUNT; path = (char)c + path; x += DIR_X[j]; y += DIR_Y[j]; } return path; } // generate moves (child nodes) in all possible directions for(int i = 0; i < Node.DIRECTION_COUNT; ++i) { int xdx = x + DIR_X[i]; int ydy = y + DIR_Y[i]; // boundary check if (!(xdx >= 0 && xdx < COL_COUNT && ydy >= 0 && ydy < ROW_COUNT)) continue; if ( ( gridMap.getData( ydy, xdx ) == GridMap.WALKABLE || gridMap.getData( ydy, xdx ) == GridMap.FINISH) && close_nodes_map[ydy][xdx] != 1 ) { // generate a child node m0 = new Node( xdx, ydy, n0.getIterCount(), n0.getPriority() ); m0.nextLevel( i ); m0.updatePriority( finishX, finishY ); // if it is not in the open list then add into that if( open_nodes_map[ydy][xdx] == 0 ) { open_nodes_map[ydy][xdx] = m0.getPriority(); nodeList[nlIndex].push( m0 ); // mark its parent node direction dir_map[ydy][xdx] = ( i + Node.DIRECTION_COUNT / 2 ) % Node.DIRECTION_COUNT; } else if( open_nodes_map[ydy][xdx] > m0.getPriority() ) { // update the priority info open_nodes_map[ydy][xdx] = m0.getPriority(); // update the parent direction info dir_map[ydy][xdx] = ( i + Node.DIRECTION_COUNT / 2 ) % Node.DIRECTION_COUNT; // replace the node // by emptying one queueList to the other one // except the node to be replaced will be ignored // and the new node will be pushed in instead while( !(nodeList[nlIndex].peek().getX() == xdx && nodeList[nlIndex].peek().getY() == ydy ) ) { nodeList[1 - nlIndex].push( nodeList[nlIndex].pop() ); } nodeList[nlIndex].pop(); // remove the wanted node // empty the larger size queueList to the smaller one if( nodeList[nlIndex].size() > nodeList[ 1 - nlIndex ].size() ) nlIndex = 1 - nlIndex; while( !nodeList[nlIndex].isEmpty() ) { nodeList[1 - nlIndex].push( nodeList[nlIndex].pop() ); } nlIndex = 1 - nlIndex; nodeList[nlIndex].push( m0 ); // add the better node instead } } } } return ""; // no route found } Output1: Legends . = PATH ? = START X = FINISH 3,2,1 = OBSTACLES (Misleading path) Output2: Changing these lines: n0 = new Node( a, b, c, d ); m0 = new Node( e, f, g, h ); to n0.set( a, b, c, d ); m0.set( e, f, g, h ); I get (I'm really confused) C++ Code: std::string A_Star::findPath(int startX, int startY, int finishX, int finishY) { typedef std::queue<Node> List_Container; List_Container nodeList[2]; // list of open (not-yet-tried) nodes Node n0; Node m0; int pqIndex = 0; // nodeList index // reset the node maps for(int y = 0;y < ROW_COUNT; ++y) { for(int x = 0;x < COL_COUNT; ++x) { close_nodes_map[y][x] = 0; open_nodes_map[y][x] = 0; } } // create the start node and push into list of open nodes n0 = Node( startX, startY, 0, 0 ); n0.updatePriority( finishX, finishY ); nodeList[pqIndex].push( n0 ); open_nodes_map[startY][startX] = n0.getPriority(); // mark it on the open nodes map // A* search while( !nodeList[pqIndex].empty() ) { List_Container &pq = nodeList[pqIndex]; // get the current node w/ the highest priority // from the list of open nodes n0 = Node( pq.front().getX(), pq.front().getY(), pq.front().getIterCount(), pq.front().getPriority()); int x = n0.getX(); int y = n0.getY(); nodeList[pqIndex].pop(); // remove the node from the open list open_nodes_map[y][x] = 0; // mark it on the closed nodes map close_nodes_map[y][x] = 1; // quit searching when the goal state is reached //if((*n0).estimate(finishX, finishY) == 0) if( x == finishX && y == finishY ) { // generate the path from finish to start // by following the directions std::string path = ""; while( !( x == startX && y == startY) ) { int j = dir_map[y][x]; char c = '0' + ( j + DIRECTION_COUNT / 2 ) % DIRECTION_COUNT; path = c + path; x += DIR_X[j]; y += DIR_Y[j]; } return path; } // generate moves (child nodes) in all possible directions for(int i = 0; i < DIRECTION_COUNT; ++i) { int xdx = x + DIR_X[i]; int ydy = y + DIR_Y[i]; // boundary check if (!( xdx >= 0 && xdx < COL_COUNT && ydy >= 0 && ydy < ROW_COUNT)) continue; if ( ( pGrid->getData(ydy,xdx) == WALKABLE || pGrid->getData(ydy, xdx) == FINISH) && close_nodes_map[ydy][xdx] != 1 ) { // generate a child node m0 = Node( xdx, ydy, n0.getIterCount(), n0.getPriority() ); m0.nextLevel( i ); m0.updatePriority( finishX, finishY ); // if it is not in the open list then add into that if( open_nodes_map[ydy][xdx] == 0 ) { open_nodes_map[ydy][xdx] = m0.getPriority(); nodeList[pqIndex].push( m0 ); // mark its parent node direction dir_map[ydy][xdx] = ( i + DIRECTION_COUNT / 2 ) % DIRECTION_COUNT; } else if( open_nodes_map[ydy][xdx] > m0.getPriority() ) { // update the priority info open_nodes_map[ydy][xdx] = m0.getPriority(); // update the parent direction info dir_map[ydy][xdx] = ( i + DIRECTION_COUNT / 2 ) % DIRECTION_COUNT; // replace the node // by emptying one nodeList to the other one // except the node to be replaced will be ignored // and the new node will be pushed in instead while ( !( nodeList[pqIndex].front().getX() == xdx && nodeList[pqIndex].front().getY() == ydy ) ) { nodeList[1 - pqIndex].push( nodeList[pqIndex].front() ); nodeList[pqIndex].pop(); } nodeList[pqIndex].pop(); // remove the wanted node // empty the larger size nodeList to the smaller one if( nodeList[pqIndex].size() > nodeList[ 1 - pqIndex ].size() ) pqIndex = 1 - pqIndex; while( !nodeList[pqIndex].empty() ) { nodeList[1-pqIndex].push(nodeList[pqIndex].front()); nodeList[pqIndex].pop(); } pqIndex = 1 - pqIndex; nodeList[pqIndex].push( m0 ); // add the better node instead } } } } return ""; // no route found } Output: Legends . = PATH ? = START X = FINISH 3,2,1 = OBSTACLES (Just right) From what I read about Java's documentation, I came up with the conclusion: C++'s std::queue<T>::front() == Java's LinkedList<T>.peek() Java's LinkedList<T>.pop() == C++'s std::queue<T>::front() + std::queue<T>::pop() What might I be missing in my Java version? In what way does it became different algorithmically from the C++ version?

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• What OpenGL functions are not GPU accelerated?

  - by Xavier Ho

  I was shocked when I read this (from the OpenGL wiki): glTranslate, glRotate, glScale Are these hardware accelerated? No, there are no known GPUs that execute this. The driver computes the matrix on the CPU and uploads it to the GPU. All the other matrix operations are done on the CPU as well : glPushMatrix, glPopMatrix, glLoadIdentity, glFrustum, glOrtho. This is the reason why these functions are considered deprecated in GL 3.0. You should have your own math library, build your own matrix, upload your matrix to the shader. For a very, very long time I thought most of the OpenGL functions use the GPU to do computation. I'm not sure if this is a common misconception, but after a while of thinking, this makes sense. Old OpenGL functions (2.x and older) are really not suitable for real-world applications, due to too many state switches. This makes me realise that, possibly, many OpenGL functions do not use the GPU at all. So, the question is: Which OpenGL function calls don't use the GPU? I believe knowing the answer to the above question would help me become a better programmer with OpenGL. Please do share some of your insights.

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• Chicken and egg problem (restore database) when trying to write unit test against SQl Server 2008.

  - by Hamish Grubijan

  Ok, they are not unit tests but end-to-end tests. The setup is somewhat involved. Unit tests will use C#, ODBC connection. Every unit tests will try to clean up after itself, but every 20 tests or so (once per C# class) we would need to do a full database restore. I do not think I can do it over an ODBC connection, according to this document: http://www.sql-server-performance.com/articles/dba/Obtain_Exclusive_Access_to_Restore_SQL_Server_p1.aspx Msg 6104, Level 16, State 1, Line 1 Cannot use KILL to kill your own process. However, I would like to, so that 199 tests do not go amok because of a bad clean-up. Is there another way? Perhaps I can open a different "connection" such as use COM automation or something of that sort, and then kill all database connections from there? If so, how can I do that? Also, will the clients be able to re-connect automatically after a restore, or would I have to dismantle everything once every 20 tests or so? If you find this question confusing, please let me know what your questions are. Thanks!

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• The correct usage of nested #pragma omp for directives

  - by GoldenLee

  The following code runs like a charm before OpenMP parallelization was applied. In fact, the following code was in a state of endless loop! I'm sure that's result from my incorrect use to the OpenMP directives. Would you please show me the correct way? Thank you very much. #pragma omp parallel for for (int nY = nYTop; nY <= nYBottom; nY++) { for (int nX = nXLeft; nX <= nXRight; nX++) { // Use look-up table for performance dLon = theApp.m_LonLatLUT.LonGrid()[nY][nX] + m_FavoriteSVISSRParams.m_dNadirLon; dLat = theApp.m_LonLatLUT.LatGrid()[nY][nX]; // If you don't want to use longitude/latitude look-up table, uncomment the following line //NOMGeoLocate.XYToGEO(dLon, dLat, nX, nY); if (dLon > 180 || dLat > 180) { continue; } if (Navigation.GeoToXY(dX, dY, dLon, dLat, 0) > 0) { continue; } // Skip void data scanline dY = dY - nScanlineOffset; // Compute coefficients as well as its four neighboring points' values nX1 = int(dX); nX2 = nX1 + 1; nY1 = int(dY); nY2 = nY1 + 1; dCx = dX - nX1; dCy = dY - nY1; dP1 = pIRChannelData->operator [](nY1)[nX1]; dP2 = pIRChannelData->operator [](nY1)[nX2]; dP3 = pIRChannelData->operator [](nY2)[nX1]; dP4 = pIRChannelData->operator [](nY2)[nX2]; // Bilinear interpolation usNomDataBlock[nY][nX] = (unsigned short)BilinearInterpolation(dCx, dCy, dP1, dP2, dP3, dP4); } }

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• Loop to check all 14 days in the pay period

  - by Rachel Ann Arndt

  Name: Calc_Anniversary Input: Pay_Date, Hire_Date, Termination_Date Output: "Y" if is the anniversary of the employee's Hire_Date, "N" if it is not, and "T" if he has been terminated before his anniversary. Description: Create local variables to hold the month and day of the employee's Date_of_Hire, Termination_Date, and of the processing date using the TO_CHAR function. First check to see if he was terminated before his anniversary. The anniversary could be on any day during the pay period, so there will be a loop to check all 14 days in the pay period to see if one was his anniversary. CREATE OR replace FUNCTION Calc_anniversary( incoming_anniversary_date IN VARCHAR2) RETURN BOOLEAN IS hiredate VARCHAR2(20); terminationdate VARCHAR(20); employeeid VARCHAR2(38); paydate NUMBER := 0; BEGIN SELECT Count(arndt_raw_time_sheet_data.pay_date) INTO paydate FROM arndt_raw_time_sheet_data WHERE paydate = incoming_anniversary_date; WHILE paydate <= 14 LOOP SELECT To_char(employee_id, '999'), To_char(hire_date, 'DD-MON'), To_char(termination_date, 'DD-MON') INTO employeeid, hiredate, terminationdate FROM employees, time_sheet WHERE employees.employee_id = time_sheet.employee_id AND paydate = pay_date; IF terminationdate > hiredate THEN RETURN 'T'; ELSE IF To_char(SYSDATE, 'DD-MON') = To_char(hiredate, 'DD-MON')THEN RETURN 'Y'; ELSE RETURN 'N'; END IF; END IF; paydate := paydate + 1; END LOOP; END; Tables I am using CREATE TABLE Employees ( EMPLOYEE_ID INTEGER, FIRST_NAME VARCHAR2(15), LAST_NAME VARCHAR2(25), ADDRESS_LINE_ONE VARCHAR2(35), ADDRESS_LINE_TWO VARCHAR2(35), CITY VARCHAR2(28), STATE CHAR(2), ZIP_CODE CHAR(10), COUNTY VARCHAR2(10), EMAIL VARCHAR2(16), PHONE_NUMBER VARCHAR2(12), SOCIAL_SECURITY_NUMBER VARCHAR2(11), HIRE_DATE DATE, TERMINATION_DATE DATE, DATE_OF_BIRTH DATE, SPOUSE_ID INTEGER, MARITAL_STATUS CHAR(1), ALLOWANCES INTEGER, PERSONAL_TIME_OFF FLOAT, CONSTRAINT pk_employee_id PRIMARY KEY (EMPLOYEE_ID), CONSTRAINT fk_spouse_id FOREIGN KEY (SPOUSE_ID) REFERENCES EMPLOYEES (EMPLOYEE_ID)) / CREATE TABLE Arndt_Raw_Time_Sheet_data ( EMPLOYEE_ID INTEGER, PAY_DATE DATE, HOURS_WORKED FLOAT, SALES_AMOUNT FLOAT, CONSTRAINT pk_employee_id_pay_date_time PRIMARY KEY (EMPLOYEE_ID, PAY_DATE), CONSTRAINT fk_employee_id_time FOREIGN KEY (EMPLOYEE_ID) REFERENCES EMPLOYEES (EMployee_ID)); error FUNCTION Calc_Anniversary compiled Warning: execution completed with warning

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• C# XNA: What can cause SpriteBatch.End() to throw a NRE?

  - by Rosarch

  I don't understand what I'm doing wrong here: public void Draw(GameTime gameTime) // in ScreenManager { SpriteBatch.Begin(SpriteBlendMode.AlphaBlend); for (int i = 0; i < Screens.Count; i++) { if (Screens[i].State == Screen.ScreenState.HIDDEN) continue; Screens[i].Draw(gameTime); } SpriteBatch.End(); // null ref exception } SpriteBatch itself is not null. Some more context: public class MasterEngine : Microsoft.Xna.Framework.Game { public MasterEngine() { graphicsDeviceManager = new GraphicsDeviceManager(this); Components.Add(new GamerServicesComponent(this)); // ... spriteBatch = new SpriteBatch(graphicsDeviceManager.GraphicsDevice); screenManager = new ScreenManager(assets, gameEngine, graphicsDeviceManager.GraphicsDevice, spriteBatch); } //... protected override void Draw(GameTime gameTime) { screenManager.Draw(gameTime); // calls the problematic method base.Draw(gameTime); } } Am I failing to initialize something properly? UPDATE: As an experiment, I tried this to the constructor of MasterEngine: spriteBatch = new SpriteBatch(graphicsDeviceManager.GraphicsDevice); spriteBatch.Begin(); spriteBatch.DrawString(assets.GetAsset<SpriteFont>("calibri"), "ftw", new Vector2(), Color.White); spriteBatch.End(); This does not cause a NRE. hmm.... UPDATE 2: This does cause an NRE: protected override void Draw(GameTime gameTime) { spriteBatch.Begin(); spriteBatch.End(); // boned here //screenManager.Draw(gameTime); base.Draw(gameTime); }

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• iphone viewWillAppear not firing

  - by chzk

  I've read numerous posts about people having problems with viewWillAppear when you do not create your view heirarchy JUST right. My problem is I can't figure out what that means. If I create a RootViewController and call addSubView on that controller, I would expect the added view(s) to be wired up for viewWillAppear events. Does anyone have an example of a complex programmatic view heirarchy that successfully recieves viewWillAppear events at every level? Apple Docs state: Warning: If the view belonging to a view controller is added to a view hierarchy directly, the view controller will not receive this message. If you insert or add a view to the view hierarchy, and it has a view controller, you should send the associated view controller this message directly. Failing to send the view controller this message will prevent any associated animation from being displayed. The problem is that they don't describe how to do this. What the hell does "directly" mean. How do you "indirectly" add a view. I am fairly new to Cocoa and iPhone so it would be nice if there were useful examples from Apple besides the basic Hello World crap. Any help is greatly appreciated...

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