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• VSTO Outlook - Contact iteration is SO SLOW!

  - by DustinDavis

  I'm working on an outlook add-in and I have a dialog window that allows the user to select contacts. I havent been able to find a way to use the outlook contact window so I am looping through the ContactFolder.Items and doing my work that way. The problem is that I have to handle up to 70K contacts. I tried multi-threading and many other things but it is just so slow. It takes 15 seconds to load 30k contacts. I can load and bind 500k POCO objects in milliseconds but when I need to get the contact items from outlook it just takes forever. The problem seems to be when you actually need to get a property from the contactitem it has to fetch it from the database or something. Is there a contact cache I can pull from? I only need Display and Email, nothing else. An ID would be nice but I don't need it. Can someone please tell me a better way of getting contacts from outlook or at least tell me how to open the outlook contact selection window? I was able to find code to open it but it wont let me because I'm showing a modal dialog and it wont open if there is a modal open.

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• How can I measure the time it takes a file to upload to a PHP script?

  - by Gustav Bertram

  I am trying to measure the time a script takes to upload a file to a PHP script, inside the receiving script. Here's a short example: <form action="#" enctype="multipart/form-data" method="post"> Upload: <input type="file" name="datafile" size="40"> <input type="submit" value="Send"> </form> <?php $upload_time = time() - $_SERVER['REQUEST_TIME']; echo $upload_time . " seconds."; I've submitted 4MB, 25MB, 100MB and 1.4GB files. They took anything from a fraction of a second, to almost a minute, yet the script above always yielded 0 seconds. NOTE: I know that this is a duplicate question, but the accepted answer on the other question did not work for me (at least, initially): Detect how long it takes for a file to upload (PHP) I've tried it using PHP 5.3.3 with Apache 2.2.16 on Ubuntu 10.4. UPDATE: I've discovered that both the Apache header and Ajax solutions work. In fact, the solution on the duplicate question also works. The critical element to making these solutions work is to ensure that the following values in the php.ini are sufficiently high: memory_limit = 1000M upload_max_filesize = 1000M post_max_size = 1000M I am accepting the Apache header solution, since it only uses PHP.

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• Facebook-ios-sdk with embedded UIWebView

  - by Benchtop Creative

  I'm working with the new facebook-ios-sdk and have successfully integrated the api into my native app. I am able to authenticate a user and properly setup permissions using a popup dialog with the ios-sdk classes. For a portion of my app I need to use the facebook connection within a UIWebView, using javascript and html to process data within the webview. Given that the user is already logged in and authenticated via the above routine, I would have assumed that the UIWebView would share those credentials, or that there would at least be some way to pass or assign the credentials to the webview. Unfortunately, I found this earlier post which seems to suggest that this scheme doesn't quite work (iOS - being logged-in in a webView after logging in with the SDK). Has anyone else encountered this and/or found a work around? This seems like it would be a fairly straightforward use case given that I'm not trying to launch mobile safari or something like that - it's all within the same native app. It just seems like there must be some sort of easy trick or setting that I'm missing. Maybe somehow setting cookies in the new UIWebView? or something like this?

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• "Address of" (&) an array / address of being ignored be gcc?

  - by dbarbosa

  Hi, I am a teaching assistant of a introductory programming course, and some students made this type of error: char name[20]; scanf("%s",&name); which is not surprising as they are learning... What is surprising is that, besides gcc warning, the code works (at least this part). I have been trying to understand and I wrote the following code: void foo(int *str1, int *str2) { if (str1 == str2) printf("Both pointers are the same\n"); else printf("They are not the same\n"); } int main() { int test[50]; foo(&test, test); if (&test == test) printf("Both pointers are the same\n"); else printf("They are not the same\n"); } Compiling and executing: $ gcc test.c -g test.c: In function ‘main’: test.c:12: warning: passing argument 1 of ‘foo’ from incompatible pointer type test.c:13: warning: comparison of distinct pointer types lacks a cast $ ./a.out Both pointers are the same Both pointers are the same Can anyone explain why they are not different? I suspect it is because I cannot get the address of an array (as I cannot have & &x), but in this case the code should not compile.

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• Is there an efficient algorithm to distribute resources in a way that both avoids conflict and allows bias?

  - by Steve V.

  Background (Skip this if you only care about the algorithm) At the university where I work, one of the biggest hassles in our department is classroom scheduling. For illustration purposes and to lay out the scope of the problem, here's how we do scheduling now: Professors give us a list of the classes they're teaching with the time slots they'd prefer to teach, ranked in order of priority (most desired to least desired). Administration gives us a list of the rooms we may assign along with the times those rooms are available for our department's use. We start assigning professors to rooms trying (at first) to take into account the preferences of the various professors. Inevitably, conflicts arise, professors start asking for changes, and the plan falls to pieces somewhere around professor number 30, at which point we start assigning rooms basically wherever we can fit them in, crumpled pieces of paper are everywhere, and nobody's happy. (If you've ever wondered why your class was at 9.30 in the morning on Thursday but 4 pm every other day, now you know) I have been asked to quietly investigate whether software could do this more optimally. The Actual Question Is there an algorithm to efficiently schedule a set of resources such that the following criteria are met: The algorithm must never assign two professors to the same room at the same time. The task is not complete until every professor has been assigned a room / time. The algorithm need not worry about having too many professors for the amount of time slots available. (We're not that well funded.) As much as is possible the algorithm should respect the scheduling preferences of the individual professors. I feel like I can't be the first one to ask this. Is there a efficient algorithm for this, or is this the sort of problem that can only be brute-forced?

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• Audio Streaming Latency

  - by killianmcc

  I'm writing a UDP local area network video chat system and have got the video and audio streams working. However I'm experiencing a little latency (about half a second) in the audio and was wondering what codecs would provide the least latency. I'm using NAudio (http://naudio.codeplex.com/) which provides me access to the following codecs for streaming; Speex Narrow Band (VBR) Speex Wide Band (16kHz)(VBR) Speex Ultra Wide Band (32kHz)(VBR) DSP Group TrueSpeech (8.5kbps) GSM 6.10 (13kbps) Microsoft ADPCM (32.8kbps) G.711 a-law (64kbps) G.722 16kHz (64kbps) G.711 mu-law (64kbps) PCM 8kHz 16 bit uncompressed (128kbps) I've tried them out and I'm not noticing much difference. Is there any others that I should download and try to reduce latency? I'm only going to be sending voice over the connection but I'm not really worried about quality or background noises too much. UPDATE I'm sending the audio in blocks like so; waveIn = new WaveIn(); waveIn.BufferMilliseconds = 50; waveIn.DeviceNumber = inputDeviceNumber; waveIn.WaveFormat = codec.RecordFormat; waveIn.DataAvailable += waveIn_DataAvailable; void waveIn_DataAvailable(object sender, WaveInEventArgs e) { if (connected) { byte[] encoded = codec.Encode(e.Buffer, 0, e.BytesRecorded); udpSender.Send(encoded, encoded.Length); } }

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• custom sorting or ordering a table without resorting the whole shebang

  - by fuugus

  for ten years we've been using the same custom sorting on our tables, i'm wondering if there is another solution which involves fewer updates, especially since today we'd like to have a replication/publication date and would'nt like to have our replication replicate unnecessary entries. i had a look into nested sets, but it does'nt seem to do the job for us. base table: id | a_sort ---+------- 1 10 2 20 3 30 after inserting insert into table (a_sort) values(15) an entry at the second position. id | a_sort ---+------- 1 10 2 20 3 30 4 15 ordering the table with select * from table order by a_sort and resorting all the a_sort entries, updating at least id=(2,3,4) will of course produce the desired output id | a_sort ---+------- 1 10 4 20 2 30 3 40 the column names, the column count, datatypes, a possible join, possible triggers or the way the resorting is done is/are irrelevant to the problem. also we've found some pretty neat ways to do this task fast. only; how the heck can we reduce the updates in the db to 1 or 2 max. seems like an awfully common problem. the captain obvious in me thougth once "use an a_sort float(53), insert using a fixed value of ordervaluefirstentry+abs(ordervaluefirstentry-ordervaluenextentry)/2".. but this would only allow around 1040 "in between" entries - so never resorting seems a bit problematic ;)

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• Usage of setInfoClass() on DirectoryIterator vs on RecursiveDirectoryIterator

  - by Gordon

  I've ran into an inconsistent behavior when using setInfoClass to set a custom SplFileInfo class to a DirectoryIterator versus setting it to a RecursiveIterator. The method description states: Use this method to set a custom class which will be used when getFileInfo and getPathInfo are called. The class name passed to this method must be derived from SplFileInfo. Consider this custom SplFileInfo class A extends SplFileInfo { public function test() { printf("I am of class %s\n", __CLASS__); } } and my iterators $iterator = new DirectoryIterator('.'); and $iterator = new RecursiveDirectoryIterator('.'); Now I'd expect those two to behave the same when I do $iterator->setInfoClass('A'); foreach($iterator as $file) { $file->test(); } and output 'I am of A' for each $file encountered and in fact, the RecursiveDirectoryIterator will do that. But the DirectoryIterator will raise Fatal error: Call to undefined method DirectoryIterator::test() so apparently the InfoClass does not get applied when iterating over the files. At least not directly, because when I change the code in the foreach loop to $file->getPathInfo()->test(); it will work for the DirectoryIterator. But then the RecursiveDirectoryIterator will raise Fatal error: Call to undefined method SplFileInfo::test() Like I said, I'd expect those two to behave the same, but apparently getFileInfo and getPathInfo don't get called in the DirectoryIterator, which I consider a bug. So if there is any Iterator experts out there, please help me understand this. Thanks.

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• What is better for a student programming in C++ to learn for writing GUI: C# vs QT?

  - by flashnik

  I'm a teacher(instructor) of CS in the university. The course is based on Cormen and Knuth and students program algorithms in C++. But sometimes it is good to show how an algorithm works or just a result of task through GUI. Also in my opinion it's very imporant to be able to write full programs. They will have courses concerning GUI but a three years, later, in fact, before graduatuion. I think that they should be able to write simple GUI applications earlier. So I want to teach them it. How do you think, what is more useful for them to learn: programming GUI with QT or writing GUI in C# and calling unmanaged C++ library? Update. For developing C++ applications students use MS Visual studio, so C# is already installed. But QT AFAIK also can be integrated into VS. I have following pros of C# (some were suggested there in answers): The need to make an additional layer. It's more work, but it forces you explicitly specify contract between GUI and processing data. The border between GUI and algorithms becomes very clear. It's more popular among employers. At least, in Russia where we live. It's rather common to write performance-critical algorithms in C++ and PInvoke them from well-looking C# application/ASP.Net website. Maybe it is not so widespread in the rest of the world but in Russia Windows is very popular, especially in companies and corporations due to some reasons, so most of b2b applications are Windows applications. Rapid development. It's much quicker to code in .Net then in C++ due to many reasons. And the con is that it's a new language with own specific for students. And the mess with invoking calls to library.

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• Should I learn two (or more) programming languages in parallel?

  - by c_maker

  I found entries on this site about learning a new programming language, however, I have not come across anything that talks about the advantages and disadvantages of learning two languages at the same time. Let's say my goal is to learn two new languages in a year. I understand that the definition of learning a new language is different for everyone and you can probably never know everything about a language. I believe in most cases the following things are enough to include the language in your resume and say that you are proficient in it (list is not in any particular order): Know its syntax so you can write a simple program in it Compare its underlying concepts with concepts of other languages Know best practices Know what libraries are available Know in what situations to use it Understand the flow of a more complex program At least know most of what you do not know I would probably look for a good book and pick an open source project for both of these languages to start with. My questions: Is it best to spend 5 months learning language#1 then 5 months learning language#2, or should you mix the two. Mixing them I mean you work on them in parallel. Should you pick two languages that are similar or different? Are there any advantages/disadvantages of let's say learning Lisp in tandem with Ruby? Is it a good idea to pick two languages with similar syntax or would it be too confusing? Please tell me what your experiences are regarding this. Does it make a difference if you are a beginner or a senior programmer?

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• SQL - Query range between two dates (NON-VBA)

  - by Mohgeroth

  I see various topics on this around stack overflow but none that fit the contect of MS-Access... Given a starting date and an ending date, is there a way through SQL to return records for each given month within the time frame? EG: Between #1/1/2010# and #12/31/2010# results #1/4/2010# #1/11/2010# ..... #12/27/2010# Restrictions MS-Access 2003 :No Case/Loops inside the SQL (IIF statements are good) This is a view only, NO VBA will be used since the data will not be tampered with. Disconnected recordset is my last option. I would prefer to find out theres some way to call your customized functions in the SQL to help return these values... some class stored on a global scope while you iterate through this date range maybe... Is this possible? I see many no's, but if there was a way to pass a value into a function I could find a way to make this work. Sad that I don't have a way to simulate a stored procedure without using a d/c recordset, at least that I know of... any experts out there know a way?

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• CI + Joomla 1.5

  - by DMin

  Hi, This is something that I just cooked up with Joomla and CodeIgniter(CI). I Wrote my database intensive application in CodeIgniter and frontend is Joomla. I'm using Jumi(Joomla Extention) so I can include the CI files inside joomla to basically insert the content generated by CI into Joomla articles. Problem is, you can't include CI files directly using JUMI from joomla because CI tends to route the pages so instead of seeing your joomla page with the CI content, you be redirected to the CI page itself. I did a little work around for this : Made an additional page that just basically does cURL to the CI page - gets the data and echos it out. From jumi, I include this cURL page instead. Couple of questions: I've seen at least a few posts that CI + Joomla is difficult to do(link). 1) Do you see any glaring security issues or possible performance issues? 2) Do you know of a better way to implement this? 3) What do you think of this? Do you think this is a good way to do this? There is one component out there that plugs CI with Joomla but it requires you to have a fresh CI install. It allows only one controller & the download link is down as well.

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• Why can a public class not inherit from a less visible one?

  - by Dan Tao

  I apologize if this question has been asked before. I've searched SO somewhat and wasn't able to find it. I'm just curious what the rationale behind this design was/is. Obviously I understand that private/internal members of a base type cannot, nor should they, be exposed through a derived public type. But it seems to my naive thinking that the "hidden" parts could easily remain hidden while some base functionality is still shared and a new interface is exposed publicly. I'm thinking of something along these lines: Assembly X internal class InternalClass { protected virtual void DoSomethingProtected() { // Let's say this method provides some useful functionality. // Its visibility is quite limited (only to derived types in // the same assembly), but at least it's there. } } public class PublicClass : InternalClass { public void DoSomethingPublic() { // Now let's say this method is useful enough that this type // should be public. What's keeping us from leveraging the // base functionality laid out in InternalClass's implementation, // without exposing anything that shouldn't be exposed? } } Assembly Y public class OtherPublicClass : PublicClass { // It seems (again, to my naive mind) that this could work. This class // simply wouldn't be able to "see" any of the methods of InternalClass // from AssemblyX directly. But it could still access the public and // protected members of PublicClass that weren't inherited from // InternalClass. Does this make sense? What am I missing? }

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• How to find out style of NSUserNotification during run-time? Or force close an alert?

  - by Dmitri Shuralyov

  According to "OS X Mountain Lion Release Notes" (https://developer.apple.com/library/mac/#releasenotes/Cocoa/Foundation.html), "The user has ultimate control over what notifications are displayed, and the style (banner, alert, etc). There is no mechanism to override the user preferences." Even though all I want to do is "downgrade" from alert style to banner style... Fine. But can I at least find out whether a notification is of alert or banner style inside the didActivateNotification method? The reason I want to do that is to respond differently according to notification.activationType. When the alert is a banner (which is what I want), clicking its contents is the only possible action, and this both triggers didActivateNotification method and closes the notification banner. When the user chooses alert-style notifications, clicking the alert contents also generates didActivateNotification with the same value of notification.activationType, but it stays on screen instead of going away (it only goes away when the Action button is pressed). I don't want my app to trigger an action repeatedly for the same alert notification, in case the user clicks the content area of an alert notification. An alternative solution would be to force the alert notification bubble to dismiss when the user clicks its contents. Is this possible?

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• Android Plugin for Eclipse problem

  - by tbneff

  I am using a laptop with Windows 7 Home Prem x64. I have installed Java JDK1.6.0_18 and Eclipse Gallileo. I have downloaded and installed the latest version of Android SDK with several Platforms loaded and a AVD defined. I can install the Android Eclipse plugin from the remote site stated in the instructions. The plugin installation performs without any errors and I can verify that the plugins are indeed installed. My problem begins when I go to Windows - Preferences, there is no Android section to configure. And when I go to File - New - Project, there is no Android Project to choose. I have uninstalled the plugin and reinstalled at least 10 times, trying different things and still no luck. I originally had the 64 bit version of the JDK installed, but removed it and installed the 32 bit version. Has anyone heard of this type of problem? Is it because I am using Windows 7? Thanks for any help. tbneff

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• Querying using table-valued parameter

  - by antmx

  I need help please with writing a sproc, it takes a table-valued parameter @Locations, whose Type is defined as follows: CREATE TYPE [dbo].[tvpLocation] AS TABLE( [CountryId] [int] NULL, [ResortName] [nvarchar](100) NULL, [Ordinal] [int] NOT NULL, PRIMARY KEY CLUSTERED ( [Ordinal] ASC )WITH (IGNORE_DUP_KEY = OFF) ) @Locations will contain at least 1 row. Each row WILL have a non-null CountryId, and MAY have a non-null ResortName. Each row will have a unique Ordinal, the first being 0. The combinations of CountryId and ResortName in @Locations will be unique. The sproc needs to search against the following table structure. The image can be seen better by right-clicking it and View Image, or similar depending on your browser. Now this is where I'm stuck, the sproc should be able to find Tours where: The Tour's 1st TourHotel (Ordinal 0) has the same CountryId (and ResortName if specified) of the 1st row of @Locations (Ordinal 0). And also if @Locations has 1 row, the Tour must have additional TourHotels, ALL of which must be in the remaining CountryIds (and ResortNames if specified) of these remaining @Locations rows. Edit This is the code I finally used, based on Anthony Faull's suggestion. Thank you so much Anthony: select distinct T.Id from tblTour T join tblTourHotel TH on TH.TourId = T.Id join tblHotel H ON H.Id = TH.HotelId JOIN @Locations L ON ( ( L.Ordinal = 0 AND TH.Ordinal = 0 ) OR ( L.Ordinal > 0 AND TH.Ordinal > 0 ) ) AND L.CountryId = H.CountryId AND ( L.ResortName = H.ResortName OR L.ResortName IS NULL ) cross apply( select COUNT(TH2.Id) AS [Count] FROM tblTourHotel TH2 where TH2.TourId = TH.TourId ) TourHotelCount where TourHotelCount.[Count] = @LocationCount group by T.Id, T.TourRef, T.Description, T.DepartureDate, T.NumNights, T.DepartureAirportId, T.DestinationAirportId, T.AirlineId, T.FEPrice having COUNT(distinct TH.Id) = @LocationCount

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• OpenCV compare two images and get different pixels

  - by Richard Knop

  For some reason the code bellow is not working. I have two 640*480 images which are very similar but not the same (at least few hundred/thousand pixels should be different). This is how I am comparing them and counting different pixels: unsigned char* row; unsigned char* row2; int count = 0; // this happens in a loop // fIplImageHeader is current image // lastFIplImageHeader is image from previous iteration if ( NULL != lastFIplImageHeader->imageData ) { for( int y = 0; y < fIplImageHeader->height; y++ ) { row = &CV_IMAGE_ELEM( fIplImageHeader, unsigned char, y, 0 ); row2 = &CV_IMAGE_ELEM( lastFIplImageHeader, unsigned char, y, 0 ); for( int x = 0; x < fIplImageHeader->width*fIplImageHeader->nChannels; x += fIplImageHeader->nChannels ) { if (row[x] == row2[x]) // the pixel in the first channel (usually G) { count++; } if (row[x+1] == row2[x+1]) // ... second channel (usually B) { count++; } if (row[x+2] == row2[x+2]) // ... third channel (usually R) { count++; } } } } Now at the end I get number 3626 which would seem alright. But, I tried opening one of the images in MS Paint and drawing thick red lines all over it which should increase the number of different pixels substantially. I got the same number again: 3626. Obviously I am doing something wrong here. I am comparing these images in a loop. This line is before the loop: IplImage* lastFIplImageHeader = cvCreateImageHeader(cvSize(640, 480), 8, 3); Then inside the loop I load images like this: IplImage* fIplImageHeader = cvLoadImage( filePath.c_str() ); // here I compare the pixels (the first code snippet) lastFIplImageHeader->imageData = fIplImageHeader->imageData; So lastFIplImageHeader is storing the image from the previous iteration and fIplImageHeader is storing the current image.

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• Collision Detection (Ground & Slopes) in 2D Platform Game using Pygame Rects

  - by RedCap

  Hi, First off, I am not after any instructions on logic for collision detection; I get it. What I am trying to work out is the least complicated way to do this with Pygame using Sprites & Rects. I want to be able to check collisions for the Player against ground, walls & slopes. In theory it is quite straight forward, but I'm having difficulty because it seems like you cannot do this with one Rect. One Rect is simple enough to get you collisions in the X plane against walls. The same Rect could be used also be used in the Y plane against solids, but not with slopes - since with the collision routines in Pygame it checks the whole Rect (or mask), rather than perhaps just the bottom middle of the Rect. It seems in addition you need to have a number of "sprites" to check collisions with, that are 1x1 pixel in various places around the Player. What's the easiest way to do this, without having a bunch of 3, 4, or more separate "collision pixels" to check against slopes? Geoff

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• Is Storing Cookies in a Database Safe?

  - by viatropos

  If I use mechanize, I can, for instance, create a new google analytics profile for a website. I do this by programmatically filling out the login form and storing the cookies in the database. Then, for at least until the cookie expires, I can access my analytics admin panel without having to enter my username and password again. Assuming you can't create a new analytics profile any other way (with OpenAuth or any of that, I don't think it works for actually creating a new Google Analytics profile, the Analytics API is for viewing the data, but I need to create an new analytics profile), is storing the cookie in the database a bad thing? If I do store the cookie in the database, it makes it super easy to programatically login to Google Analytics without the user ever having to go to the browser (maybe the app has functionality that says "user, you can schedule a hook that creates a new anaytics profile for each new domain you create, just enter your credentials once and we'll keep you logged in and safe"). Otherwise I have to keep transferring around emails and passwords which seems worse. So is storing cookies in the database safe?

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• C# - Is it possible to start my project with a class instead of a form?

  - by Irro

  I want my project to be started through an class instead of a form, is there any way to do this? Or to be more precise is there any good way to make sure that the first class, except Program, that is started isn't a form-class. I tried to change to my class in Program.main() but it looks like Application.run() needs a ApplicationContext. I guess that I could change the Program-class to start another class and let that class start the form with Application.run() but I think that it will cause a lot of problem since I don't want the same form to be started first each time and Application.run() have to be used at least once and at most once. So I think it will be hard to keep track of if Application.run() has been used or not. Another question that might be even more important; Is this a good way to do things in .net? The reason I want to do so is because I want to create some sort of MVC project where the class I want to start with is the controller and all forms I'll use will be views.

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• C++ gdb GUI

  - by HappyDude

  Briefly: Does anyone know of a GUI for gdb that brings it on par or close to the feature set you get in the more recent version of Visual C++? In detail: As someone who has spent a lot of time programming in Windows, one of the larger stumbling blocks I've found whenever I have to code C++ in Linux is that debugging anything using commandline gdb takes me several times longer than it does in Visual Studio, and it does not seem to be getting better with practice. Some things are just easier or faster to express graphically. Specifically, I'm looking for a GUI that: Handles all the basics like stepping over & into code, watch variables and breakpoints Understands and can display the contents of complex & nested C++ data types Doesn't get confused by and preferably can intelligently step through templated code and data structures while displaying relevant information such as the parameter types Can handle threaded applications and switch between different threads to step through or view the state of Can handle attaching to an already-started process or reading a core dump, in addition to starting the program up in gdb If such a program does not exist, then I'd like to hear about experiences people have had with programs that meet at least some of the bullet points. Does anyone have any recommendations? Edit: Listing out the possibilities is great, and I'll take what I can get, but it would be even more helpful if you could include in your responses: (a) Whether or not you've actually used this GUI and if so, what positive/negative feedback you have about it. (b) If you know, which of the above-mentioned features are/aren't supported Lists are easy to come by, sites like this are great because you can get an idea of people's personal experiences with applications.

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• MySQL: optimization of table (indexing, foreign key) with no primary keys

  - by Haradzieniec

  Each member has 0 or more orders. Each order contains at least 1 item. memberid - varchar, not integer - that's OK (please do not mention that's not very good, I can't change it). So, thera 3 tables: members, orders and order_items. Orders and order_items are below: CREATE TABLE `orders` ( `orderid` INT(11) UNSIGNED NOT NULL AUTO_INCREMENT, `memberid` VARCHAR( 20 ), `Time` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP , `info` VARCHAR( 3200 ) NULL , PRIMARY KEY (orderid) , FOREIGN KEY (memberid) REFERENCES members(memberid) ) ENGINE = InnoDB; CREATE TABLE `order_items` ( `orderid` INT(11) UNSIGNED NOT NULL, `item_number_in_cart` tinyint(1) NOT NULL , --- 5 items in cart= 5 rows `price` DECIMAL (6,2) NOT NULL, FOREIGN KEY (orderid) REFERENCES orders(orderid) ) ENGINE = InnoDB; So, order_items table looks like: orderid - item_number_in_cart - price: ... 1000456 - 1 - 24.99 1000456 - 2 - 39.99 1000456 - 3 - 4.99 1000456 - 4 - 17.97 1000457 - 1 - 20.00 1000458 - 1 - 99.99 1000459 - 1 - 2.99 1000459 - 2 - 69.99 1000460 - 1 - 4.99 ... As you see, order_items table has no primary keys (and I think there is no sense to create an auto_increment id for this table, because once we want to extract data, we always extract it as WHERE orderid='1000456' order by item_number_in_card asc - the whole block, id woudn't be helpful in queries). Once data is inserted into order_items, it's not UPDATEd, just SELECTed. The questions are: I think it's a good idea to put index on item_number_in_cart. Could anybody please confirm that? Is there anything else I have to do with order_items to increase the performance, or that looks pretty good? I could miss something because I'm a newbie. Thank you in advance.

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• Optimizing near-duplicate value search

  - by GApple

  I'm trying to find near duplicate values in a set of fields in order to allow an administrator to clean them up. There are two criteria that I am matching on One string is wholly contained within the other, and is at least 1/4 of its length The strings have an edit distance less than 5% of the total length of the two strings The Pseudo-PHP code: foreach($values as $value){ foreach($values as $match){ if( ( $value['length'] < $match['length'] && $value['length'] * 4 > $match['length'] && stripos($match['value'], $value['value']) !== false ) || ( $match['length'] < $value['length'] && $match['length'] * 4 > $value['length'] && stripos($value['value'], $match['value']) !== false ) || ( abs($value['length'] - $match['length']) * 20 < ($value['length'] + $match['length']) && 0 < ($match['changes'] = levenshtein($value['value'], $match['value'])) && $match['changes'] * 20 <= ($value['length'] + $match['length']) ) ){ $matches[] = &$match; } } } I've tried to reduce calls to the comparatively expensive stripos and levenshtein functions where possible, which has reduced the execution time quite a bit. However, as an O(n^2) operation this just doesn't scale to the larger sets of values and it seems that a significant amount of the processing time is spent simply iterating through the arrays. Some properties of a few sets of values being operated on Total | Strings | # of matches per string | | Strings | With Matches | Average | Median | Max | Time (s) | --------+--------------+---------+--------+------+----------+ 844 | 413 | 1.8 | 1 | 58 | 140 | 593 | 156 | 1.2 | 1 | 5 | 62 | 272 | 168 | 3.2 | 2 | 26 | 10 | 157 | 47 | 1.5 | 1 | 4 | 3.2 | 106 | 48 | 1.8 | 1 | 8 | 1.3 | 62 | 47 | 2.9 | 2 | 16 | 0.4 | Are there any other things I can do to reduce the time to check criteria, and more importantly are there any ways for me to reduce the number of criteria checks required (for example, by pre-processing the input values), since there is such low selectivity?

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• Grab two parts of a single, short string

  - by TankorSmash

  I'm looking to fill a python dict with TAG:definition pairs, and I'm using RegExr http://gskinner.com/RegExr/ to write the regex My first step is to parse a line, from http://www.id3.org/id3v2.3.0, or http://pastebin.com/VJEBGauL and pull out the ID3 tag and the associated definition. For example the first line: 4.20 AENC [#sec4.20 Audio encryption] would look like this myDict = {'AENC' : 'Audio encryption'} To grab the tag name, I've got it looking for at least 3 spaces, then 4 characters, then 4 spaces: {3}[a-zA-Z0-9]{4} {4} That part is easy enough. The second part, the definition, is not working out for me. So far, I've got (?<=(\[#.+?)) A Which should find, but not include the [# as well as an indeterminded set of characters until it finds: _A, but it's failing. If I remove .+? and replace _A with s it works out alright. What is going wrong? *The underscores represent spaces, which don't show up on SO. How do I grab the definition, ie,(Audio encryption) of the ID3v2 tag from the line, using RegEx?

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• ServiceLoader double iterator issues

  - by buge

  Is this a known issue? I had trouble finding any search results. When iterating over a ServiceLoader while an iteration already is in progress, the first iteration will be aborted. For example, assuming there are at least two implementations of Foo, the following code will fail with an AssertionError: ServiceLoader<Foo> loader = ServiceLoader.load(Foo.class); Iterator<Foo> iter1 = loader.iterator(); iter1.next(); Iterator<Foo> iter2 = loader.iterator(); while (iter2.hasNext()) { iter2.next(); } assert iter1.hasNext(); This only seems to occur, if the second iterator really terminates. The code will succeed in this variation for example: ServiceLoader<Foo> loader = ServiceLoader.load(Foo.class); Iterator<Foo> iter1 = loader.iterator(); iter1.next(); Iterator<Foo> iter2 = loader.iterator(); iter2.next(); assert iter1.hasNext(); Is this a bug or a feature? :p Is there a ticket for this already anywhere?

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