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  • Get the equivalent time between "dynamic" time zones

    - by doctore
    I have a table providers that has three columns (containing more columns but not important in this case): starttime, start time in which you can contact him. endtime, final hour in which you can contact him. region_id, region where the provider resides. In USA: California, Texas, etc. In UK: England, Scotland, etc starttime and endtime are time without timezone columns, but, "indirectly", their value has time zone of the region in which the provider resides. For example: starttime | endtime | region_id (time zone of region) | "real" st | "real" et ----------|----------|---------------------------------|-----------|----------- 03:00:00 | 17:00:00 | 1 (EGT => -1) | 02:00:00 | 16:00:00 Often I need to get the list of suppliers whose time range is within the current server time (taking into account the time zone conversion). The problem is that the time zones aren't "constant", ie, they may change during the summer time. However, this change is very specific to the region and not always carried out at the same time: EGT <= EGST, ART <= ARST, etc. The question is: 1. Is it necessary to use a webservice to update every so often the time zones in the regions? Does anyone know of a web service that can serve? 2. Is there a better approach to solve this problem? Thanks in advance. UPDATE I will give an example to clarify what I'm trying to get. In the table providers I found this records: idproviders | starttime | endtime | region_id ------------|-----------|----------|----------- 1 | 03:00:00 | 17:00:00 | 23 (Texas) 2 | 04:00:00 | 18:00:00 | 23 (Texas) If I execute the query in January, with this information: Server time (UTC offset) = 0 hours Texas providers (UTC offset) = +1 hour Server time = 02:00:00 I should get the following results: idproviders = 1 If I execute the query in June, with this information: Server time (UTC offset) = 0 hours Texas providers (UTC offset) = +2 hours (their local time has not changed, but their time zone has changed) Server time = 02:00:00 I should get the following results: idproviders = 1 and 2

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  • Match subpatterns in any order

    - by Yaroslav
    I have long regexp with two complicated subpatters inside. How i can match that subpatterns in any order? Simplified example: /(apple)?\s?(banana)?\s?(orange)?\s?(kiwi)?/ and i want to match both of apple banana orange kiwi apple orange banana kiwi It is very simplified example. In my case banana and orange is long complicated subpatterns and i don't want to do something like /(apple)?\s?((banana)?\s?(orange)?|(orange)?\s?(banana)?)\s?(kiwi)?/ Is it possible to group subpatterns like chars in character class? UPD Real data as requested: 14:24 26,37 Mb 108.53 01:19:02 06.07 24.39 19:39 46:00 my strings much longer, but it is significant part. Here you can see two lines what i need to match. First has two values: length (14 min 24 sec) and size 26.37 Mb. Second one has three values but in different order: size 108.53 Mb, length 01 h 19 m 02 s and date June, 07 Third one has two size and length Fourth has only length There are couple more variations and i need to parse all values. I have a regexp that pretty close except i can't figure out how to match patterns in different order without writing it twice. (?<size>\d{1,3}\[.,]\d{1,2}\s+(?:Mb)?)?\s? (?<length>(?:(?:01:)?\d{1,2}:\d{2}))?\s* (?<date>\d{2}\.\d{2}))? NOTE: that is only part of big regexp that forks fine already.

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  • What is the preferred way in C++ for converting a builtin type (int) to bool?

    - by Martin
    When programming with Visual C++, I think every developer is used to see the warning warning C4800: 'BOOL' : forcing value to bool 'true' or 'false' from time to time. The reason obviously is that BOOL is defined as int and directly assigning any of the built-in numerical types to bool is considered a bad idea. So my question is now, given any built-in numerical type (int, short, ...) that is to be interpreted as a boolean value, what is the/your preferred way of actually storing that value into a variable of type bool? Note: While mixing BOOL and bool is probably a bad idea, I think the problem will inevitably pop up whether on Windows or somewhere else, so I think this question is neither Visual-C++ nor Windows specific. Given int nBoolean; I prefer this style: bool b = nBoolean?true:false; The following might be alternatives: bool b = !!nBoolean; bool b = (nBoolean != 0); Is there a generally preferred way? Rationale? I should add: Since I only work with Visual-C++ I cannot really say if this is a VC++ specific question or if the same problem pops up with other compilers. So it would be interesting to specifically hear from g++ or users how they handle the int-bool case. Regarding Standard C++: As David Thornley notes in a comment, the C++ Standard does not require this behavior. In fact it seems to explicitly allow this, so one might consider this a VC++ weirdness. To quote the N3029 draft (which is what I have around atm.): 4.12 Boolean conversions [conv.bool] A prvalue of arithmetic, unscoped enumeration, pointer, or pointer to member type can be converted to a prvalue of type bool. A zero value, null pointer value, or null member pointer value is converted to false; any other value is converted to true. (...)

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  • How to generate lots of redundant ajax elements like checkboxes and pulldowns in Django?

    - by iJames
    Hello folks. I've been getting lots of answers from stackoverflow now that I'm in Django just be searching. Now I hope my question will also create some value for everybody. In choosing Django, I was hoping there was some similar mechanism to the way you can do partials in ROR. This was going to help me in two ways. One was in generating repeating indexed forms or form elements, and also in rendering only a piece of the page on the round trip. I've done a little bit of that by using taconite with a simple URL click but now I'm trying to get more advanced. This will focus on the form issue which boils down to how to iterate over a secondary object. If I have a list of photo instances, each of which has a couple of parameters, let's say a size and a quantity. I want to generate form elements for each photo instance separately. But then I have two lists I want to iterate on at the same time. Context: photos : Photo.objects.all() and forms = {} for photo in photos: forms[photo.id] = PhotoForm() In other words we've got a list of photo objects and a dict of forms based on the photo.id. Here's an abstraction of the template: {% for photo in photos %} {% include "photoview.html" %} {% comment %} So here I want to use the photo.id as an index to get the correct form. So that each photo has its own form. I would want to have a different action and each form field would be unique. Is that possible? How can I iterate on that? Thanks! {% endcomment %} Quantity: {{ oi.quantity }} {{ form.quantity }} Dimensions: {{ oi.size }} {{ form.size }} {% endfor %} What can I do about this simple case. And how can I make it where every control is automatically updating the server instead of using a form at all? Thanks! James

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  • Thoughts about alternatives to barplot-with-error-bars

    - by gd047
    I was thinking of an alternative to the barplot-with-error-bars plot. To get an idea by example, I roughly 'sketched' what I mean using the following code library(plotrix) plot(0:12,type="n",axes=FALSE) gradient.rect(1,0,3,8,col=smoothColors("red",38,"red"),border=NA,gradient="y") gradient.rect(4,0,6,6,col=smoothColors("blue",38,"blue"),border=NA,gradient="y") lines(c(2,2),c(5.5,10.5)) lines(c(2-.5,2+.5),c(10.5,10.5)) lines(c(2-.5,2+.5),c(5.5,5.5)) lines(c(5,5),c(4.5,7.5)) lines(c(5-.5,5+.5),c(7.5,7.5)) lines(c(5-.5,5+.5),c(4.5,4.5)) gradient.rect(7,8,9,10.5,col=smoothColors("red",100,"white"),border=NA,gradient="y") gradient.rect(7,5.5,9,8,col=smoothColors("white",100,"red"),border=NA,gradient="y") lines(c(7,9),c(8,8),lwd=3) gradient.rect(10,6,12,7.5,col=smoothColors("blue",100,"white"),border=NA,gradient="y") gradient.rect(10,4.5,12,6,col=smoothColors("white",100,"blue"),border=NA,gradient="y") lines(c(10,12),c(6,6),lwd=3) The idea was to use bars like the ones in the second pair, instead of those in the first. However, there is something that I would like to change in the colors. Instead of a linear gradient fill, I would like to adjust the color intensity in accordance with the values of the pdf of the mean estimator. Do you think it is possible? A slightly different idea (where gradient fill isn't an issue) was to use one (or 2 back-to-back) bell curve(s) filled with (solid) color, instead of a rectangle. See for example the shape that corresponds to the letter F here. In that case the bell-curve(s) should (ideally) be drawn using something like plot(x, dnorm(x, mean = my.mean, sd = std.error.of.the.mean)) I have no idea though, of a way to draw rotated (and filled with color) bell curves. Of course, all of the above may be freely judged as midnight springtime dreams :-)

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  • resizing images with imagemagick via shell script

    - by jml
    Hi there, I don't really know that much about bash scripts OR imagemagick, but I am attempting to create a script in which you can give some sort of regexp matching pattern for a list of images and then process those into new files that have a given filename prefix. for example given the following dir listing: allfiles01.jpg allfiles02.jpg allfiles03.jpg i would like to call the script like so: ./resisemany.sh allfiles*.jpg 30 newnames*.jpg the end result of this would be that you get a bunch of new files with newnames, the numbers match up, so far what i have is: IMAGELIST=$1 RESIEZFACTOR=$2 NUMIMGS=length($IMAGELIST) for(i=0; i<NUMIMGS; i++) convert $IMAGELIST[i] -filter bessel -resize . RESIZEFACTOR . % myfile.JPG Thanks for any help... The parts that I obviously need help with are 1. how to give a bash script matching criteria that it understands 2. how to use the $2 without having it match the 2nd item in the image list 3. how to get the length of the image list 4. how to create a proper for loop in such a case 5. how to do proper text replacement for a shell command whereby you are appending items as i allude to. jml

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  • Float addition promoted to double?

    - by Andreas Brinck
    I had a small WTF moment this morning. Ths WTF can be summarized with this: float x = 0.2f; float y = 0.1f; float z = x + y; assert(z == x + y); //This assert is triggered! (Atleast with visual studio 2008) The reason seems to be that the expression x + y is promoted to double and compared with the truncated version in z. (If i change z to double the assert isn't triggered). I can see that for precision reasons it would make sense to perform all floating point arithmetics in double precision before converting the result to single precision. I found the following paragraph in the standard (which I guess I sort of already knew, but not in this context): 4.6.1. "An rvalue of type float can be converted to an rvalue of type double. The value is unchanged" My question is, is x + y guaranteed to be promoted to double or is at the compiler's discretion? UPDATE: Since many people has claimed that one shouldn't use == for floating point, I just wanted to state that in the specific case I'm working with, an exact comparison is justified. Floating point comparision is tricky, here's an interesting link on the subject which I think hasn't been mentioned.

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  • Inner join on 2 arrays?

    - by russ
    I'm trying to find a solution to the following (I'm thinking with Linq) to the following: I need to pull down certain files from a larger list of files on an ftp server that have a similar file name. For example, we send an order file to some company for processing then they return a response file that we can download. So, I could send them the files "order_123.txt" and "order_456.txt". After a certain amount of time I need to go look for and download the responses for those files that will be named "order_123.resp" and "order_456.resp". The kicker is that in some cases I can have multiple responses in which case they would create "order_123-1.resp" and "order_123-2.resp" and also the files don't get removed from the server. I know this can be accomplished by looping through the files I know I need responses to then loop through all the files on the server until I find files that match but I'm hoping that I don't have to loop through the files on the server more than once. This example may help clarify: I've sent "order_222.txt" and "order_333.txt" they processed them and the ftp server contains: "order_111-1.resp" "order_001.resp" "order_222-1.resp" "order_222-2.resp" "order_333.resp" I need to download the 3rd, 4th, and 5th file. Thanks.

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  • [jQuery 1.4] move one div over another

    - by Tomasz Zielinski
    I have two div elements that are twins (i.e. their dimensions and contents are identical). I want to move of those div-s over another, so that their corners are at exactly the same coordinates. What I try to do is: var offset = $('div#placeholder').offset(); $('div#overlay').css('position', 'absolute').css('left', offset.left + 'px').css('top', offset.top + 'px') -- but this causes the overlay to be exactly (or almost exactly, taking subpixel accuracy into account) 16px below the placeholder (below, i.e. overlay_top = placeholder_top + 16px). I'm aware that offset() gives position relative to the document, and position: absolute sets position relative to body element, but compensating for body offset() doesn't help much (I'm getting 8px offset, equal to margins): offset.top -= $('body').offset().top; offset.left -= $('body').offset().left; Also, compensating for body margins (in case they were different that offset() didn't help, as they were set to 8px). Does somebody know what I'm doing wrong here? UPDATE: Take a look at here - I'm getting the same result in FireFox 3.6.3 and Opera 10.10.

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  • Storing array as value in associative array

    - by Jagannath
    i have a problem where I need to have an array as value in associative array. Go through the code below. Here I am trying to loop the files in a directory and it is more likely that more than 1 file can have the same ctrno. So, I would like to see what are all the files having the same ctrno. The code below gives error at "$ctrno_hash[$ctrno] = @arr;" in the else condition. The same case would be for if condition as well. Am I following the right approach or could it be done diffently? sub loop_through_files { $file = "@_"; open(INPFILE, "$file") or die $!; #print "$file:$ctrno\n"; while (<INPFILE>) { $line .= $_; } if ($line =~ /$ctrno/ ) { print "found\n"; if ( exists $ctrno_hash[$ctrno]) { local @arr = $ctrno_hash[$ctrno]; push (@arr, $file); $ctrno_hash[$ctrno] = @arr; } else { local @arr; push(@arr, $file); $ctrno_hash[$ctrno] = @arr; } } }

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  • Can I interrupt javascript code and then continue on a keystroke?

    - by Brian Ramsay
    I am porting an old game from C to Javascript. I have run into an issue with display code where I would like to have the main game code call display methods without having to worry about how those status messages are displayed. In the original code, if the message is too long, the program just waits for the player to toggle through the messages with the spacebar and then continues. This doesn't work in javascript, because while I wait for an event, all of the other program code continues. I had thought to use a callback so that further code can execute when the player hits the designated key, but I can't see how that will be viable with a lot of calls to display.update(msg) scattered throughout the code. Can I architect things differently so the event-based, asynchronous model works, or is there some other solution that would allow me to implement a more traditional event loop? Am I making sense? Example: // this is what the original code does, but obviously doesn't work in Javascript display = { update : function(msg) { // if msg is too long // wait for user input // ok, we've got input, continue } }; // this is more javascript-y... display = { update : function(msg, when_finished) { // show part of the message $(document).addEvent('keydown', function(e) { // display the rest of the message when_finished(); }); } }; // but makes for amazingly nasty game code do_something(param, function() { // in case do_something calls display I have to // provide a callback for everything afterwards // this happens next, but what if do_the_next_thing needs to call display? // I have to wait again do_the_next_thing(param, function() { // now I have to do this again, ad infinitum } }

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  • BASH: How to count all the human readable files?

    - by user1687406
    I'm taking an intro course to UNIX and have a homework question that follows: How many files in the previous question are text files? A text file is any file containing human-readable content. (TRICK QUESTION. Run the file command on a file to see whether the file is a text file or a binary data file! If you simply count the number of files with the ".txt" extension you will get no points for this question.) The previous question simply asked how many regular files there were, which was easy to figure out by doing find . -type f | wc -l I'm just having trouble determining what "human readable content" is, since I'm assuming it means anything besides binary/assembly, but I thought that's what -type f displays. Maybe that's what the professor meant by saying "trick question"? This question has a follow up later that also asks "What text files contain the string "csc" in any mix of upper and lower case?". Obviously "text" is referring to more than just .txt files, but I need to figure out the first question to determine this!

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  • Silverlight 3 data-binding child property doesn't update

    - by sonofpirate
    I have a Silverlight control that has my root ViewModel object as it's data source. The ViewModel exposes a list of Cards as well as a SelectedCard property which is bound to a drop-down list at the top of the view. I then have a form of sorts at the bottom that displays the properties of the SelectedCard. My XAML appears as (reduced for simplicity): <StackPanel Orientation="Vertical"> <ComboBox DisplayMemberPath="Name" ItemsSource="{Binding Path=Cards}" SelectedItem="{Binding Path=SelectedCard, Mode=TwoWay}" /> <TextBlock Text="{Binding Path=SelectedCard.Name}" /> <ListBox DisplayMemberPath="Name" ItemsSource="{Binding Path=SelectedCard.PendingTransactions}" /> </StackPanel> I would expect the TextBlock and ListBox to update whenever I select a new item in the ComboBox, but this is not the case. I'm sure it has to do with the fact that the TextBlock and ListBox are actually bound to properties of the SelectedCard so it is listening for property change notifications for the properties on that object. But, I would have thought that data-binding would be smart enough to recognize that the parent object in the binding expression had changed and update the entire binding. It bears noting that the PendingTransactions property (bound to the ListBox) is lazy-loaded. So, the first time I select an item in the ComboBox, I do make the async call and load the list and the UI updates to display the information corresponding to the selected item. However, when I reselect an item, the UI doesn't change! For example, if my original list contains three cards, I select the first card by default. Data-binding does attempt to access the PendingTransactions property on that Card object and updates the ListBox correctly. If I select the second card in the list, the same thing happens and I get the list of PendingTransactions for that card displayed. But, if I select the first card again, nothing changes in my UI! Setting a breakpoint, I am able to confirm that the SelectedCard property is being updated correctly. How can I make this work???

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  • PHP: What is an efficient way to parse a text file containing very long lines?

    - by Shaun
    I'm working on a parser in php which is designed to extract MySQL records out of a text file. A particular line might begin with a string corresponding to which table the records (rows) need to be inserted into, followed by the records themselves. The records are delimited by a backslash and the fields (columns) are separated by commas. For the sake of simplicity, let's assume that we have a table representing people in our database, with fields being First Name, Last Name, and Occupation. Thus, one line of the file might be as follows [People] = "\Han,Solo,Smuggler\Luke,Skywalker,Jedi..." Where the ellipses (...) could be additional people. One straightforward approach might be to use fgets() to extract a line from the file, and use preg_match() to extract the table name, records, and fields from that line. However, let's suppose that we have an awful lot of Star Wars characters to track. So many, in fact, that this line ends up being 200,000+ characters/bytes long. In such a case, taking the above approach to extract the database information seems a bit inefficient. You have to first read hundreds of thousands of characters into memory, then read back over those same characters to find regex matches. Is there a way, similar to the Java String next(String pattern) method of the Scanner class constructed using a file, that allows you to match patterns in-line while scanning through the file? The idea is that you don't have to scan through the same text twice (to read it from the file into a string, and then to match patterns) or store the text redundantly in memory (in both the file line string and the matched patterns). Would this even yield a significant increase in performance? It's hard to tell exactly what PHP or Java are doing behind the scenes.

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  • PHP GD imagecreatefromstring discards transparency

    - by meustrus
    I've been trying to get transparency to work with my application (which dynamically resizes images before storing them) and I think I've finally narrowed down the problem after much misdirection about imagealphablending and imagesavealpha. The source image is never loaded with proper transparency! // With this line, the output image has no transparency (where it should be // transparent, colors bleed out randomly or it's completely black, depending // on the image) $img = imagecreatefromstring($fileData); // With this line, it works as expected. $img = imagecreatefrompng($fileName); // Blah blah blah, lots of image resize code into $img2 goes here; I finally // tried just outputting $img instead. header('Content-Type: image/png'); imagealphablending($img, FALSE); imagesavealpha($img, TRUE); imagepng($img); imagedestroy($img); It would be some serious architectural difficulty to load the image from a file; this code is being used with a JSON API that gets queried from an iPhone app, and it's easier in this case (and more consistent) to upload images as base64-encoded strings in the POST data. Do I absolutely need to somehow store the image as a file (just so that PHP can load it into memory again)? Is there maybe a way to create a Stream from $fileData that can be passed to imagecreatefrompng?

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  • How to store data in mysql, to get the fastest performance?

    - by Oden
    Hey, I'm thinking about it, witch of the following two query types would give me the fastest performance for a user messaging module inside my site: The first one i thought about is a multi table setup, witch has a connection table, and a main table. The connection table holds the connection between accounts, and the messaging table. In this case a query would look like following, to get some data of the author, and the messages he has sent: SELECT m.*, a.username FROM messages AS m LEFT JOIN connection_table ON (message_id = m.id) LEFT JOIN accounts AS a ON (account_id = a.id) WHERE m.id = '32341' Inserting into it is a little bit more "complicated". My other idea, and in my thought the better solution of this problem is that i store the data i would use in a connection table in the same table where is store the data of the mail. Sounds like i would get lots of duplicated entries, but no, because i have a field witch has text type and holds user ids like this: *24*32*249* If I want to query them, i use the mysql LIKE method. Deleting is an other problem, but for this i have one more field where i store who has deleted the post. Sad about that i don't know how to join this. So what would you recommend? Are there other ways?

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  • UITableViewIndex Grows to Incorrect Bounds Unexpectedly

    - by chadburggraf
    I have a standard UITableView + UISearchDisplayController + UITableViewIndex setup. Everything works like a champ. Except, under very specific conditions, the index grows too long to display on the screen. Specifically, after ending a search and re-displaying the unfiltered, indexed table, the index sometimes grows too long. More specifically, this doesn't happen if I search then cancel. It only happens if I search, then push a view controller from the search table, then pop that view controller back to the still-searching table, then cancel the search, then re-search and then cancel that final search. After the end of the final search the index is too long. In portrait, the table view is reporting a height of 416 and the index a height of 404 under normal conditions. If I log from searchDisplayControllerDidEndSearch when the index is sized incorrectly, it is reporting a height of 620. I've tried everything from setLayout on the table and the index to manually re-sizing the frame. Nothing works (the manual re-size causes the correct height to be logged, but it doesn't change the display on screen). I was about to try re-sizing after a delay in case the cancel animation was interfering, but then I realized what an absurd situation I'm in and thought seeking help might be wise...

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  • How does static code run with multiple threads?

    - by Krisc
    I was reading http://stackoverflow.com/questions/1511798/threading-from-within-a-class-with-static-and-non-static-methods and I am in a similar situation. I have a static method that pulls data from a resource and creates some runtime objects based on the data. static class Worker{ public static MyObject DoWork(string filename){ MyObject mo = new MyObject(); // ... does some work return mo; } } The method takes awhile (in this case it is reading 5-10mb files) and returns an object. I want to take this method and use it in a multiple thread situation so I can read multiple files at once. Design issues / guidelines aside, how would multiple threads access this code? Let's say I have something like this... class ThreadedWorker { public void Run() { Thread t = new Thread(OnRun); t.Start(); } void OnRun() { MyObject mo = Worker.DoWork("somefilename"); mo.WriteToConsole(); } } Does the static method run for each thread, allowing for parallel execution?

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  • Agile language for 2d game prototypes?

    - by instanceofTom
    Occasionally ( read: when my fiancé allows ) I like to prototype different game or game-like ideas I have. Usually I use Java or C# (not xna yet) because they are the languages I have the most practice with. However I would like to learn something more suited to agile development; a language in which it would be easier to knock out quick prototypes. At my job I have recently been working with looser (weak/dynamically typed) languages, specifically python and groovy, and I think something similar would fit what I am looking for. So, my question is: What languages (and framework/engine) would be good for rapidly developing prototypes of 2d game concepts? A few notes: I don't need blazing fast bitcrunching performance. In this case I would strongly prefer ease of development over performance. I'd like to use a language with a healthy community, which to me means a fair amount of maintained 3rd party, libraries. I'd like the language to be cross-platform friendly, I work on a variety of different operating systems and would like something that is portable with minimum effort. I can't imagine myself using a language with out decent options for debugging and editor syntax highlighting support. Note: If you are aware of a Java or C# library/framework that you think streamlines producing game prototypes I open to learning something new for those languages too

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  • C++: is it safe to work with std::vectors as if they were arrays?

    - by peoro
    I need to have a fixed-size array of elements and to call on them functions that require to know about how they're placed in memory, in particular: functions like glVertexPointer, that needs to know where the vertices are, how distant they are one from the other and so on. In my case vertices would be members of the elements to store. to get the index of an element within this array, I'd prefer to avoid having an index field within my elements, but would rather play with pointers arithmetic (ie: index of Element *x will be x - & array[0]) -- btw, this sounds dirty to me: is it good practice or should I do something else? Is it safe to use std::vector for this? Something makes me think that an std::array would be more appropriate but: Constructor and destructor for my structure will be rarely called: I don't mind about such overhead. I'm going to set the std::vector capacity to size I need (the size that would use for an std::array, thus won't take any overhead due to sporadic reallocation. I don't mind a little space overhead for std::vector's internal structure. I could use the ability to resize the vector (or better: to have a size chosen during setup), and I think there's no way to do this with std::array, since its size is a template parameter (that's too bad: I could do that even with an old C-like array, just dynamically allocating it on the heap). If std::vector is fine for my purpose I'd like to know into details if it will have some runtime overhead with respect to std::array (or to a plain C array): I know that it'll call the default constructor for any element once I increase its size (but I guess this won't cost anything if my data has got an empty default constructor?), same for destructor. Anything else?

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  • Postgre database ignoring created index ?!

    - by drasto
    I have an Postgre database and a table called my_table. There are 4 columns in that table (id, column1, column2, column3). The id column is primary key, there are no other constrains or indexes on columns. The table has about 200000 rows. I want to print out all rows which has value of column column2 equal(case insensitive) to 'value12'. I use this: SELECT * FROM my_table WHERE column2 = lower('value12') here is the execution plan for this statement(result of set enable_seqscan=on; EXPLAIN SELECT * FROM my_table WHERE column2 = lower('value12')): Seq Scan on my_table (cost=0.00..4676.00 rows=10000 width=55) Filter: ((column2)::text = 'value12'::text) I consider this to be to slow so I create an index on column column2 for better prerformance of searches: CREATE INDEX my_index ON my_table (lower(column2)) Now I ran the same select: SELECT * FROM my_table WHERE column2 = lower('value12') and I expect it to be much faster because it can use index. However it is not faster, it is as slow as before. So I check the execution plan and it is the same as before(see above). So it still uses sequential scen and it ignores the index! Where is the problem ?

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  • Strategy for locale sensitive sort with pagination

    - by Thom Birkeland
    Hi, I work on an application that is deployed on the web. Part of the app is search functions where the result is presented in a sorted list. The application targets users in several countries using different locales (= sorting rules). I need to find a solution for sorting correctly for all users. I currently sort with ORDER BY in my SQL query, so the sorting is done according to the locale (or LC_LOCATE) set for the database. These rules are incorrect for those users with a locale different than the one set for the database. Also, to further complicate the issue, I use pagination in the application, so when I query the database I ask for rows 1 - 15, 16 - 30, etc. depending on the page I need. However, since the sorting is wrong, each page contains entries that are incorrectly sorted. In a worst case scenario, the entire result set for a given page could be out of order, depending on the locale/sorting rules of the current user. If I were to sort in (server side) code, I need to retrieve all rows from the database and then sort. This results in a tremendous performance hit given the amount of data. Thus I would like to avoid this. Does anyone have a strategy (or even technical solution) for attacking this problem that will result in correctly sorted lists without having to take the performance hit of loading all data? Tech details: The database is PostgreSQL 8.3, the application an EJB3 app using EJB QL for data query, running on JBoss 4.5.

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  • What does it mean to say "Instance variables are not over-rided" in java?

    - by Ankit
    I am aware of the concept called field hiding in java. But still I am having a confusion in relation to instance variable being not over-ridden. According to my present knowledge, overriding a method of super-class means that the JVM will call the sub-class's over-ridden method though the super-class's method is available to the sub-class. And I read the similar thing for field hiding via the link:- Hiding Fields So, in any case we are over-ridding the instance if we change the values of the inherited instance variable in the sub-class. I am confused please help. I am using the following super-class:- public class Animal{ File picture; String food; int hunger; int width, height; int xcoord, ycoord; public void makeNoise(){ ......... } public void eat(){ ............. } public void sleep(){ .......... } public void roam(){ ............. } } It has sub-classes like Tiger, cat, dog,hippo etc. The sub-classes over-ride the makeNoise(), eat and roam() method. But each sub-class also uses a different set of values for instance variables. So as per my confusion, I am kind-of overriding all the instance variables and 3 methods of the super-class Animal; and I still have the super-class instance variables available to the sub-class with the use of the super keyword.

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  • How to access elements in a complex list?

    - by Martin
    Hi, it's me and the lists again. I have a nice list, which looks like this: tmp = NULL t = NULL tmp$resultitem$count = "1057230" tmp$resultitem$status = "Ok" tmp$resultitem$menu = "PubMed" tmp$resultitem$dbname = "pubmed" t$resultitem$count = "305215" t$resultitem$status = "Ok" t$resultitem$menu = "PMC" t$resultitem$dbname = "pmc" tmp = c(tmp, t) t = NULL t$resultitem$count = "1" t$resultitem$status = "Ok" t$resultitem$menu = "Journals" t$resultitem$dbname = "journals" tmp = c(tmp, t) Which produces: str(tmp) List of 3 $ resultitem:List of 4 ..$ count : chr "1057230" ..$ status: chr "Ok" ..$ menu : chr "PubMed" ..$ dbname: chr "pubmed" $ resultitem:List of 4 ..$ count : chr "305215" ..$ status: chr "Ok" ..$ menu : chr "PMC" ..$ dbname: chr "pmc" $ resultitem:List of 4 ..$ count : chr "1" ..$ status: chr "Ok" ..$ menu : chr "Journals" ..$ dbname: chr "journals" Now I want to search through the elements of each "resultitem". I want to know the "dbname" for every database, that has less then 10 "count" (example). In this case it is very easy, as this list only has 3 elements, but the real list is a little bit longer. This could be simply done with a for loop. But is there a way to do this with some other function of R (like rapply)? My problem with those apply functions is, that they only look at one element. If I do a grep to get all "dbname" elements, I can not get the count of each element. rapply(tmp, function(x) paste("Content: ", x))[grep("dbname", names(rapply(tmp, c)))] Does someone has a better idea than a for loop? Thanx, Martin

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  • Reverse Two Consecutive Lines

    - by thebourneid
    I have this part of a code for editing cue sheets and I don't know how to reverse two consecutive lines if found: /^TITLE.*?"$/ /^PERFORMER.*?"$/ to reverse to /^PERFORMER.*?"$/ /^TITLE.*?"$/ What would it be the solution in my case? use strict; use warnings; use File::Find; use Tie::File; my $dir_target = 'test'; find(\&c, $dir_target); sub c { /\.cue$/ or return; my $fn = $File::Find::name; tie my @lines, 'Tie::File', $fn or die "could not tie file: $!"; for (my $i = 0; $i < @lines; $i++) { if ($lines[$i] =~ /^REM (DATE|GENRE|REPLAYGAIN).*?$/) { splice(@lines, $i, 3); } if ($lines[$i] =~ /^\s+REPLAYGAIN.*?$/) { splice(@lines, $i, 1); } } untie @lines; }

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