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• Time complexity to fill hash table (homework)?

  - by Heathcliff

  This is a homework question, but I think there's something missing from it. It asks: Provide a sequence of m keys to fill a hash table implemented with linear probing, such that the time to fill it is minimum. And then Provide another sequence of m keys, but such that the time fill it is maximum. Repeat these two questions if the hash table implements quadratic probing I can only assume that the hash table has size m, both because it's the only number given and because we have been using that letter to address a hash table size before when describing the load factor. But I can't think of any sequence to do the first without knowing the hash function that hashes the sequence into the table. If it is a bad hash function, such that, for instance, it hashes every entry to the same index, then both the minimum and maximum time to fill it will take O(n) time, regardless of what the sequence looks like. And in the average case, where I assume the hash function is OK, how am I suppossed to know how long it will take for that hash function to fill the table? Aren't these questions linked to the hash function stronger than they are to the sequence that is hashed? As for the second question, I can assume that, regardless of the hash function, a sequence of size m with the same key repeated m-times will provide the maximum time, because it will cause linear probing from the second entry on. I think that will take O(n) time. Is that correct? Thanks

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• Display image background fully for last repeat in a div

  - by Stiggler

  I have a 700x300 background repeating seamlessly under the main content-div. Now I'd like to attach a div at the bottom of the content-div, containing a continuation-to-end of the background image, connecting seamlessly with the background above it. Due to the nature of the pattern, unless the full 300px height of the background image is visible in the last repeat of the content-div's backround, the background in the div below won't seamlessly connect. Basically, I need the content div's height to be a multiple of 300px under all circumstances. What's a good approach to this sort of problem? I've tried resizing the content-div on loading the page, but this only works as long as the content div doesn't contain any resizing, dynamic content, which is not my case: function adjustContentHeight() { // Setting content div's height to nearest upper multiple of column backgrounds height, // forcing it not to be cut-off when repeated. var contentBgHeight = 300; var contentHeight = $("#content").height(); var adjustedHeight = Math.ceil(contentHeight / contentBgHeight); $("#content").height(adjustedHeight * contentBgHeight); } $(document).ready(adjustContentHeight); What I'm looking for there is a way to respond to a div resizing event, but there doesn't seem to be such a thing. Also, please assume I have no access to the JS controlling the resizing of content in the content-div, though this is potentially a way of solving the problem. Another potential solution I was thinking off was to offset the background image in the bottom div by a certain amount depending on the height of the content-div. Again, the missing piece seems to be the ability to respond to a resize event.

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• Assemble an image browser side with JavaScript or Flash?

  - by Kris Walker

  Would it be possible to assemble an image on the browser by 'concatenating' other downloaded images together? The use case is this. The page will display 36 different tiles (small images). The user should be able to arrange those tiles into a 6 x 6 grid and save the resulting grid to disk as an image. The best solution would be to do it all in the browser without Flash. The next best solution would be to allow the user to create the grid in the browser with simple JavaScript drag and drop functionality and then send the coordinates to the server for image processing. The last solution would be to do it all in the browser with Flash. Is it even possible for Flash to create an image and then allow the user to save it from the browser? I am familiar with the Pixastic JavaScript library ( http://www.pixastic.com/ ), but it relies on getting image data to and from a canvas element which is not very well supported. What if I send the tile images to the browser as base64 encoded strings? Could I use JavaScript to create the 6 x 6 grid image? And if so, is there some way of allowing the user to get it onto disk without relying on the canvas element?

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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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• accessing a method from a button within a class?

  - by flo

  #import "GameObject.h" #import "Definitions.h" @implementation GameObject @synthesize owner; @synthesize state; @synthesize mirrored; @synthesize button; @synthesize switcher; - (id) init { if ( self = [super init] ) { [self setOwner: EmptyField]; button = [UIButton buttonWithType:UIButtonTypeCustom]; [self setSwitcher: FALSE]; } return self; } - (UIButton*) display{ button.frame = CGRectMake(0, 0, GO_Width, GO_Height); [button setBackgroundImage:[UIImage imageNamed:BlueStone] forState:UIControlStateNormal]; [button addTarget:self action:@selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside]; return button; } -(void)buttonPressed:(id) sender { //... } } - (void) dealloc { [super dealloc]; } @end Hi! i would like to know if the above is possible somehow within a class (in my case it is called GameObject) or if i HAVE to have the button call a methode in the viewcontroller... the above results with the app crashing. i would call display within a loop on the viewcontroller and id like to change some of the GameObjects instance variables within buttonPressed. Also id like to change some other stuff by calling some other methods from within buttonPressed but i think that will be the lesser of my problems ;) also id like to know how i can pass some variables to the buttonPressed method... cant find it anywhere :( help on this one would be much appreciated ;) thanks flo

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• DataReader already open when using LINQ

  - by Jamie Dixon

  I've got a static class containing a static field which makes reference to a wrapper object of a DataContext. The DataContext is basically generated by Visual Studio when we created a dbml file & contains methods for each of the stored procedures we have in the DB. Our class basically has a bunch of static methods that fire off each of these stored proc methods & then returns an array based on a LINQ query. Example: public static TwoFieldBarData[] GetAgesReportData(string pct) { return DataContext .BreakdownOfUsersByAge(Constants.USER_MEDICAL_PROFILE_KEY, pct) .Select(x => new TwoFieldBarData(x.DisplayName, x.LeftValue, x.RightValue, x.TotalCount)) .ToArray(); } Every now and then, we get the following error: There is already an open DataReader associated with this Command which must be closed firs This is happening intermittently and I'm curious as to what is going on. My guess is that when there's some lag between one method executing and the next one firing, it's locking up the DataContext and throwing the error. Could this be a case for wrapping each of the DataContext LINQ calls in a lock(){} to obtain exclusivity to that type and ensure other requests are queued?

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• WM_NOTIFY and superclass chaining issue in Win32

  - by DasMonkeyman

  For reference I'm using the window superclass method outlined in this article. The specific issue occurs if I want to handle WM_NOTIFY messages (i.e. for custom drawing) from the base control in the superclass I either need to reflect them back from the parent window or set my own window as the parent (passed inside CREATESTRUCT for WM_(NC)CREATE to the base class). This method works fine if I have a single superclass. If I superclass my superclass then I run into a problem. Now 3 WindowProcs are operating in the same HWND, and when I reflect WM_NOTIFY messages (or have them sent to myself from the parent trick above) they always go to the outermost (most derived) WindowProc. I have no way to tell if they're messages intended for the inner superclass (base messages are supposed to go to the first superclass) or messages intended for the outer superclass (messages from the inner superclass are intended for the outer superclass). These messages are indistinguishable because they all come from the same HWND with the same control ID. Is there any way to resolve this without creating a new window to encapsulate each level of inheritance? Sorry about the wall of text. It's a difficult concept to explain. Here's a diagram. single superclass: SuperA::WindowProc() - Base::WindowProc()---\ ^--------WM_NOTIFY(Base)--------/ superclass of a superclass: SuperB::WindowProc() - SuperA::WindowProc() - Base::WindowProc()---\ ^--------WM_NOTIFY(Base)--------+-----------------------/ ^--------WM_NOTIFY(A)-----------/ The WM_NOTIFY messages in the second case all come from the same HWND and control ID, so I cannot distinguish between the messages intended for SuperA (from Base) and messages intended for SuperB (from SuperA). Any ideas?

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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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• jQuery event "looping"

  - by Deryck

  Hi I´m trying to code a tooltip (Yes I know, I have my reasons to avoid plugins in this case) in jQuery. Whe I show the tooltip and leave the mouse in the same place the show and hide repeats forever. It´s like the element triggers the hover event again and again and again. I try unbind for the event but it does not work neither. $("td.with-tooltip").mouseover( function() { var offset = $(this).offset(); var baseX = offset.left; var baseY = offset.top; var inputWidth = $(this).width(); var baseX = baseX + 50; var baseY = baseY - $(".desc").height(); $(".desc div").html($(this).attr("title")); $(".desc").css({"position":"absolute", "left": baseX, "top": baseY }).fadeIn(); $(this).unbind("mouseover"); }).mouseleave( function() { $(".desc").fadeOut(); }); What can I do? thanks.

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• wrapping user controls in a transaction

  - by Hans Gruber

  I'm working on heavily dynamic and configurable CMS system. Therefore, many pages are composed of a dynamically loaded set of user controls. To enable loose coupling between containers (pages) and children (user controls), all user controls are responsible for their own persistence. Each User Control is wired up to its data/service layer dependencies via IoC. They also implement an IPersistable interface, which allows the container .aspx page to issue a Save command to its children without knowledge of the number or exact nature of these user controls. Note: what follows is only pseudo-code: public class MyUserControl : IPersistable, IValidatable { public void Save() { throw new NotImplementedException(); } public bool IsValid() { throw new NotImplementedException(); } } public partial class MyPage { public void btnSave_Click(object sender, EventArgs e) { foreach (IValidatable control in Controls) { if (!control.IsValid) { throw new Exception("error"); } } foreach (IPersistable control in Controls) { if (!control.Save) { throw new Exception("error"); } } } } I'm thinking of using declarative transactions from the System.EnterpriseService namespace to wrap the btnSave_Click in a transaction in case of an exception, but I'm not sure how this might be achieved or any pitfalls to such an approach.

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• How can i use a commandlinetool (ie. sox) via subprocess.Popen with mod_wsgi?

  - by marue

  I have a custom django filefield that makes use of sox, a commandline audiotool. This works pretty well as long as i use the django development server. But as soon as i switch to the production server, using apache2 and mod_wsgi, mod_wsgi catches every output to stdout. This makes it impossible to use the commandline tool to evaluate the file, for example use it to check if the uploaded file really is an audio file like this: filetype=subprocess.Popen([sox,'--i','-t','%s'%self.path], shell=False,\ stdout=subprocess.PIPE, stderr=subprocess.PIPE) (filetype,error)=filetype.communicate() if error: raise EnvironmentError((1,'AudioFile error while determining audioformat: %s'%error)) Is there a way to workaround for this? edit the error i get is "missing filename". I am using mod_wsgi 2.5, standard with ubuntu 8.04. edit2 What exactly happens, when i call subprocess.Popen from within django in mod_wsgi? Shouldn't subprocess stdin/stdout be independent from django stdin/stdout? In that case mod_wsgi should not affect programms called via subprocess... I'm really confused right now, because the file i am trying to access is a temporary file, created via a filenamevariable that i pass to the file creation and the subprocess command. That file is being written to /tmp, where the rights are 777, so it can't be a rights issue. And the error message is not "file does not exist", but "missing filename", which suggests i am not passing a filename as parameter to the commandlinetool.

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• Divide and conquer of large objects for GC performance

  - by Aperion

  At my work we're discussing different approaches to cleaning up a large amount of managed ~50-100MB memory.There are two approaches on the table (read: two senior devs can't agree) and not having the experience the rest of the team is unsure of what approach is more desirable, performance or maintainability. The data being collected is many small items, ~30000 which in turn contains other items, all objects are managed. There is a lot of references between these objects including event handlers but not to outside objects. We'll call this large group of objects and references as a single entity called a blob. Approach #1: Make sure all references to objects in the blob are severed and let the GC handle the blob and all the connections. Approach #2: Implement IDisposable on these objects then call dispose on these objects and set references to Nothing and remove handlers. The theory behind the second approach is since the large longer lived objects take longer to cleanup in the GC. So, by cutting the large objects into smaller bite size morsels the garbage collector will processes them faster, thus a performance gain. So I think the basic question is this: Does breaking apart large groups of interconnected objects optimize data for garbage collection or is better to keep them together and rely on the garbage collection algorithms to processes the data for you? I feel this is a case of pre-optimization, but I do not know enough of the GC to know what does help or hinder it.

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• Korn shell wraparound

  - by allenratcliff

  Okay, I'm sure this is simple but it is driving me nuts. I recently went to work on a program where I've had to step back in time a bit and use Redhat 9. When I'm typing on the command line from a standard xterm running Korn shell, when I reach the end of the line the screen slides to the right (cutting off the left side of my command) instead of wrapping the text around to a new line. This makes things difficult for me because I can't easily copy and paste from the previous command straight from the command line. I have to look at the history and paste the command from there. In case you're wondering, I do a lot of command-line awk scripts that cause the line to get quite long. Is there a way to force the command line to wrap instead of shifting visibility to the right side of the command I'm typing? I've poured through man page options with no luck. I'm running XFree86 4.2.99.903(174) and KSH 5.2.14. Thanks.

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• How to receive Email in JEE application

  - by Hank

  Obviously it's not so difficult to send out emails from a JEE application via JavaMail. What I am interested in is the best pattern to receive emails (notification bounces, mostly)? I am not interested in IMAP/POP3-based approaches (polling the inbox) - my application shall react to inbound emails. One approach I could think of would be Keep existing MTA (postfix on linux in my case) - ops team already knows how to configure / operate it For every mail that arrives, spawn a Java app that receives the data and sends it off via JMS. I could do this via an entry in /etc/aliases like myuser: "|/path/to/javahelper" with javahelper calling the Java app, passing STDIN along. MDB (part of JEE application) receives JMS message, parses it, detects bounce message and acts accordingly. Another approach could be Open a listening network socket on port 25 on the JEE application container. Associate a SessionBean with the socket. Bean is part of JEE application and can parse/detect bounces/handle the messages directly. Keep existing MTA as inbound relay, do all its security/spam filtering, but forward emails to myuser (that pass the filter) to the JEE application container, port 25. The first approach I have done before (albeit in a different language/setup). From a performance and (perceived) cleanliness point of view, I think the second approach is better, but it would require me to provide a proper SMTP transport implementation. Also, I don't know if it's at all possible to connect a network socket with a bean... What is your recommendation? Do you have details about the second approach?

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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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• Form (or Formset?) to handle multiple table rows in Django

  - by Ben

  Hi, I'm working on my first Django application. In short, what it needs to do is to display a list of film titles, and allow users to give a rating (out of 10) to each film. I've been able to use the {{ form }} and {{ formset }} syntax in a template to produce a form which lets you rate one film at a time, which corresponds to one row in a MySQL table, but how do I produce a form that iterates over all the movie titles in the database and produces a form that lets you rate lots of them at once? At first, I thought this was what formsets were for, but I can't see any way to automatically iterate over the contents of a database table to produce items to go in the form, if you see what I mean. Currently, my views.py has this code: def survey(request): ScoreFormSet = formset_factory(ScoreForm) if request.method == 'POST': formset = ScoreFormSet(request.POST, request.FILES) if formset.is_valid(): return HttpResponseRedirect('/') else: formset = ScoreFormSet() return render_to_response('cf/survey.html', { 'formset':formset, }) And my survey.html has this: <form action="/survey/" method="POST"> <table> {{ formset }} </table> <input type = "submit" value = "Submit"> </form> Oh, and the definition of ScoreForm and Score from models.py are: class Score(models.Model): movie = models.ForeignKey(Movie) score = models.IntegerField() user = models.ForeignKey(User) class ScoreForm(ModelForm): class Meta: model = Score So, in case the above is not clear, what I'm aiming to produce is a form which has one row per movie, and each row shows a title, and has a box to allow the user to enter their score. If anyone can point me at the right sort of approach to this, I'd be most grateful. Thanks, Ben

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• Mmap and structure

  - by blid..pl

  I'm working some code including communication between processes, using semaphores. I made structure like this: typedef struct container { sem_t resource, mutex; int counter; } container; and use in that way (in main app and the same in subordinate processes) container *memory; shm_unlink("MYSHM"); //just in case fd = shm_open("MYSHM", O_RDWR|O_CREAT|O_EXCL, 0); if(fd == -1) { printf("Error"); exit(EXIT_FAILURE); } memory = mmap(NULL, sizeof(container), PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); ftruncate(fd, sizeof(container)); Everything is fine when I use one of the sem_ functions, but when I try to do something like memory->counter = 5; It doesn't work. Probably I got something wrong with pointers, but I tried almost everything and nothing seems to work. Maybe there's a better way to share variables, structures etc between processes ? Unfortunately I'm not allowed to use boost or something similiar, the code is for educational purposes and I'm intentend to keep as simple as it's possible.

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• Go - Using a map for its set properties with user defined types

  - by Seth Hoenig

  I'm trying to use the built-in map type as a set for a type of my own (Point, in this case). The problem is, when I assign a Point to the map, and then later create a new, but equal point and use it as a key, the map behaves as though that key is not in the map. Is this not possible to do? // maptest.go package main import "fmt" func main() { set := make(map[*Point]bool) printSet(set) set[NewPoint(0, 0)] = true printSet(set) set[NewPoint(0, 2)] = true printSet(set) _, ok := set[NewPoint(3, 3)] // not in map if !ok { fmt.Print("correct error code for non existent element\n") } else { fmt.Print("incorrect error code for non existent element\n") } c, ok := set[NewPoint(0, 2)] // another one just like it already in map if ok { fmt.Print("correct error code for existent element\n") // should get this } else { fmt.Print("incorrect error code for existent element\n") // get this } fmt.Printf("c: %t\n", c) } func printSet(stuff map[*Point]bool) { fmt.Print("Set:\n") for k, v := range stuff { fmt.Printf("%s: %t\n", k, v) } } type Point struct { row int col int } func NewPoint(r, c int) *Point { return &Point{r, c} } func (p *Point) String() string { return fmt.Sprintf("{%d, %d}", p.row, p.col) } func (p *Point) Eq(o *Point) bool { return p.row == o.row && p.col == o.col }

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• Using Tcl DSL in Python

  - by Sridhar Ratnakumar

  I have a bunch of Python functions. Let's call them foo, bar and baz. They accept variable number of string arguments and does other sophisticated things (like accessing the network). I want the "user" (let's assume he is only familiar with Tcl) to write scripts in Tcl using those functions. Here's an example (taken from Macports) that user can come up with: post-configure { if {[variant_isset universal]} { set conflags "" foreach arch ${configure.universal_archs} { if {${arch} == "i386"} {append conflags "x86 "} else { if {${arch} == "ppc64"} {append conflags "ppc_64 "} else { append conflags ${arch} " " } } } set profiles [exec find ${worksrcpath} -name "*.pro"] foreach profile ${profiles} { reinplace -E "s|^(CONFIG\[ \\t].*)|\\1 ${conflags}|" ${profile} # Cures an isolated case system "cd ${worksrcpath}/designer && \ ${qt_dir}/bin/qmake -spec ${qt_dir}/mkspecs/macx-g++ -macx \ -o Makefile python.pro" } } } Here, variant_issset, reinplace are so on (other than Tcl builtins) are implemented as Python functions. if, foreach, set, etc.. are normal Tcl constructs. post-configure is a Python function that accepts, well, a Tcl code block that can later be executed (which in turns would obviously end up calling the above mentioned Python "functions"). Is this possible to do in Python? If so, how? from Tkinter import *; root= Tk(); root.tk.eval('puts [array get tcl_platform]') is the only integration I know of, which is obviously very limited (not to mention the fact that it starts up X11 server on mac).

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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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• URL equals and checking Internet access

  - by James P.

  On http://java.sun.com/j2se/1.5.0/docs/api/java/net/URL.html it states that: Compares this URL for equality with another object. If the given object is not a URL then this method immediately returns false. Two URL objects are equal if they have the same protocol, reference equivalent hosts, have the same port number on the host, and the same file and fragment of the file. Two hosts are considered equivalent if both host names can be resolved into the same IP addresses; else if either host name can't be resolved, the host names must be equal without regard to case; or both host names equal to null. Since hosts comparison requires name resolution, this operation is a blocking operation. Note: The defined behavior for equals is known to be inconsistent with virtual hosting in HTTP. According to this, equals will only work if name resolution is possible. Since I can't be sure that a computer has internet access at a given time, should I just use Strings to store addresses instead? Also, how do I go about testing if access is available when requested?

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• Very slow guards in my monadic random implementation (haskell)

  - by danpriduha

  Hi! I was tried to write one random number generator implementation, based on number class. I also add there Monad and MonadPlus instance. What mean "MonadPlus" and why I add this instance? Because of I want to use guards like here: -- test.hs -- import RandomMonad import Control.Monad import System.Random x = Rand (randomR (1 ::Integer, 3)) ::Rand StdGen Integer y = do a <-x guard (a /=2) guard (a /=1) return a here comes RandomMonad.hs file contents: -- RandomMonad.hs -- module RandomMonad where import Control.Monad import System.Random import Data.List data RandomGen g => Rand g a = Rand (g ->(a,g)) | RandZero instance (Show g, RandomGen g) => Monad (Rand g) where return x = Rand (\g ->(x,g)) (RandZero)>>= _ = RandZero (Rand argTransformer)>>=(parametricRandom) = Rand funTransformer where funTransformer g | isZero x = funTransformer g1 | otherwise = (getRandom x g1,getGen x g1) where x = parametricRandom val (val,g1) = argTransformer g isZero RandZero = True isZero _ = False instance (Show g, RandomGen g) => MonadPlus (Rand g) where mzero = RandZero RandZero `mplus` x = x x `mplus` RandZero = x x `mplus` y = x getRandom :: RandomGen g => Rand g a ->g ->a getRandom (Rand f) g = (fst (f g)) getGen :: RandomGen g => Rand g a ->g -> g getGen (Rand f) g = snd (f g) when I run ghci interpreter, and give following command getRandom y (mkStdGen 2000000000) I can see memory overflow on my computer (1G). It's not expected, and if I delete one guard, it works very fast. Why in this case it works too slow? What I do wrong?

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• Applications result affected by another running application.

  - by Jamie Keeling

  This is a follow on from my previous question although this is about something else. I've been having a problem where for some reason my message that I pass from one process to another only displays the first letter, in this case "M". My application is based on a MSDN sample so to make sure I hadn't missed something I create a separate solution, added the MSDN sample (without any changes for my needs) and unsurprisingly it works fine. Now for the weird bit, when I run the MSDN sample running (as in debugging) and have my own application running, the text prints out fine without any problems. The second I run my on its own without the original MSDN sample being open, and it fails to work and only shows an "M". I've looked in the debugger and don't seem to notice anything suspicious (it's a slightly dated picture, I've fixed the data type inconsistency). Can anyone provide a solution for this? I've never encountered anything like this before. To look at my source code it's easier to just look at the link I posted at the top of the question, there's no point in me posting it twice. Thank you for any help.

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• Adroid's DateFormat replacement - missing the format() with FieldPosition

  - by user331244

  Hi, I need to split a date string into pieces and I'm doing it using the public final StringBuffer format (Object object, StringBuffer buffer, FieldPosition field) from the java.text.DateFormat class. However, the implementation of this function is really slow, hence Android has an own implementation in android.text.format.DateFormat. BUT, in my case, I want to extract the different pieces of the date string (year, minute and so on). Since I need to be locale independent, I can not use SimpleDateFormat and custom strings. I do it as follows: Calendar c = ... // find out what field to extract int field = getField(); // Create a date string Field calendarField = DateFormat.Field.ofCalendarField(field); FieldPosition fieldPosition = new FieldPosition(calendarField); StringBuffer label = new StringBuffer(); label = getDateFormat().format(c.getTime(), label, fieldPosition); // Find the piece that we are looking for int beginIndex = fieldPosition.getBeginIndex(); int endIndex = fieldPosition.getEndIndex(); String asString = label.substring(beginIndex, endIndex); For some reason, the format() overload with the FieldPosition argument is not included in the android platform. Any ideas of how to do this in another way? Is there any easy way to tokenize the pattern string? Any other ideas?

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• C Programing - Return libcurl http response to string to the calling function

  - by empty set

  I have a homework and i need somehow to compare two http responses. I am writing it on C (dumb decision) and i use libcurl to make things easier. I am calling the function that uses libcurl to http request and response from another function and i want to return the http response to it. Anyway, the code below doesn't work, any ideas? #include <stdio.h> #include <curl/curl.h> #include <string.h> size_t write_data(void *ptr, size_t size, size_t nmemb, void *stream) { size_t written; written = fwrite(ptr, size, nmemb, stream); return written; } char *handle_url(void) { CURL *curl; char *fp; CURLcode res; char *url = "http://www.yahoo.com"; curl = curl_easy_init(); if (curl) { curl_easy_setopt(curl, CURLOPT_URL, url); curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data); curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp); res = curl_easy_perform(curl); if(res != CURLE_OK) fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res)); curl_easy_cleanup(curl); //printf("\n%s", fp); } return fp; } This solution C libcurl get output into a string works, but not in my case because i want to return this string to the calling function.

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