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  • Efficient most common suffix algorithm?

    - by taw
    I have a few GBs worth of strings, and for every prefix I want to find 10 most common suffixes. Is there an efficient algorithm for that? An obvious solution would be: Store sorted list of <string, count> pairs. Identify by binary search extent for prefix we're searching. Find 10 highest counts in this extent. Possibly precompute it for all short prefixes, so it doesn't ever need to look at large portion of data. I'm not sure if that would actually be efficient at all. Is there a better way I overlooked? Answers must be real time, but it can take as much preprocessing as necessary.

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  • How difficult is it for an old-school programmer to pick up an FPGA kit and make something useful wi

    - by JUST MY correct OPINION
    I'm an old, old, old coder. (How old? I've used paper tape in anger.) I've programmed in a lot of languages and under a lot of paradigms (spaghetti, structured, object-oriented, functional and a smattering of logical). I'm getting bored. FPGAs look interesting to me. I have the crazy notion of resurrecting some of the ancient hardware I worked on in the days using FPGAs. I know this can be done because I've seen PDP-10 and PDP-11 implementations in FPGAs. I'd like to do the same for a few machines that are perhaps not as popular as those two, however. While I am an old, old coder, what I am not is an electronics or computer systems engineer. I'll be learning from scratch if I go down this path. My question, therefore, is two-fold: How difficult will it be for this old dinosaur to pick up and learn FPGAs to the point that interesting (not necessarily practical -- more from a hobbyist perspective) projects can be made? What should I start with learning-wise to go down this path? I know where to get FPGA kits, but I haven't found anything like "FPGAs for Complete Dinosaurs" yet anywhere out there.

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  • What Test Environment Setup do Committers Use in the Ruby Community?

    - by viatropos
    Today I am going to get as far as I can setting up my testing environment and workflow. I'm looking for practical advice on how to setup the test environment from you guys who are very passionate and versed in Ruby Testing. By the end of the day (6am PST?) I would like to be able to: Type one 1-command to run test suites for ANY project I find on Github. Run autotest for ANY Github project so I can fork and make TESTABLE contributions. Build gems from the ground up with Autotest and Shoulda. For one reason or another, I hardly ever run tests for projects I clone from Github. The major reason is because unless they're using RSpec and have a Rake task to run the tests, I don't see the common pattern behind it all. I have built 3 or 4 gems writing tests with RSpec, and while I find the DSL fun, it's less than ideal because it just adds another layer/language of methods I have to learn and remember. So I'm going with Shoulda. But this isn't a question about which testing framework to choose. So the questions are: What is your, the SO reader and Github project committer, test environment setup using autotest so that whenever you git clone a gem, you can run the tests and autotest-develop them if desired? What are the guys who are writing the Paperclip Tests and Authlogic Tests doing? What is their setup? Thanks for the insight. Looking for answers that will make me a more effective tester.

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  • Can you make a PHP function recursive without repeating it's name?

    - by alex
    It's always bugged me a recursive function needs to name itself, when a instantiated class can use $this and a static method can use self etc. Is there a similar way to do this in a recursive function without naming it again (just to cut down on maintenance)? Obviously I could use call_user_func or the __FUNCTION__ constant but I would prefer something less ugly. Update Thanks for your answers. I might stick to including the function name for simple functions, and make take the other approaches for anything more complicated.

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  • How can I test whether a csv file is currently open and being written to - the file, not a file hand

    - by Henry
    I've seen a few questions/answers here that deal with this, but none really give me an answer/solution. I've got a Clipper system writing csv files to a Windows directory. I have a perl script running on a Linux server that is reading a mount of that Windows directory and importing the files to a database. Right now we're using flag files to indicate when a csv is no longer being written to; the flag files gets written after the csv is done. I'd really rather just get what I need from the csv itself, but I can't seem to find a way to tell when the file is open and being written to. lsof doesn't seem to answer my need. I've tried using flock and open the file with an exclusive lock, thinking it might throw an error if the file is being modified, but it doesn't. Any thoughts?

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  • What is XcvPort (used in OpenPrinter function)

    - by RiskX
    I'm usin the OpenPrinter function and the first parameter the function gets called "pPrinterName" and that's it's MSDN description: [in] Pointer to a null-terminated string that specifies the name of the printer or print server, the printer object, the XcvMonitor, or the XcvPort. For a printer object use: PrinterName,Job xxxx. For an XcvMonitor, use: ServerName,XcvMonitor MonitorName. For an XcvPort, use: ServerName,XcvPort PortName. Obviously I'm interested in the bold part. What exactly is XcvPort? I know it seems like a question of lazy person but I really couldn't find info abou this concept. If I would like to open a printer on port ABC I should write: "\\MySrever,XcvPort ABC"? Thank you for your answers!

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  • Why do date manipulation in Java with milliseconds?

    - by staticsan
    I was recently faced with the problem of calculating the number of days from two dates in Java (without using joda, I'm afraid). Searching on the 'net shows most answers to this question say to get the milliseconds of the two days and convert that to days, which I found appalling. However, a scant few show a different approach: use a temporary variable to count how many times it takes adding 1 day to the first date to get to the second. This leaves the conversions to the code that does it best: the library. Why do so many people advocate the first? In another project, I had previously encountered numerous subtle date calculation problems involving time-zones, daylight-saving and once even leap years using seconds to do date comparisions and calculations. All these went away when all the comparison and calculation code was rewitten to use the language libraries. (This was in PHP, though, where the libraries are structured quite differently to Java.) So I'm understandably reluctant to use this "common wisdom" in the world of Java about comparing dates.

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  • find a duplicate entry in an array in constant space and O(n) time [closed]

    - by Anubhav Agarwal
    Possible Duplicate: Algorithm to find a duplicate entry in constant space and O(n) time Given an array of N integer such that only one integer is repeated. Find the repeated integer in O(n) time and constant space. There is no range for the value of integers or the value of N For example given an array of 6 integers as 23 45 67 87 23 47. The answer is 23 (I hope this covers ambiguous and vague part) I searched on the net but was unable to find any such question in which range of integers was not fixed. Also here is an example that answers a similar question to mine but here he created a hash table with the highest integer value in C++.But the cpp does not allow such to create an array with 2^64 element(on a 64-bit computer).

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  • What grid distributed computing frameworks are currently favoured for trading systems

    - by Rich
    There seems to a quite a few grid computing frameworks out there, but which ones are actually being used to any great extent by the investment banks for purposes of low latency distributing calculation? I'd be interested to hear answers covering both windows,Linux and cross platform. Also, what RPC mechanisms seem to be favoured most? I've heard that for reason of low latency and speed, the calculations themselves are quite often written in C++/C as calculations running on VMs are several orders of magnitude slower than native code. Does this seem to be a common scenario in practice? e.g distributed .NET grid framework running calculations written in native c++/c?

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  • How to generate Makefiles with Cmake to create tarballs of project?

    - by Rizo
    I like to keep my Makefiles flexible and multifunctional. One of the tasks I usually add to make command is tar, for example the following instruction does the job: tar: tar -cvf $(PROGNAME).tar $(SRCS) Makefile My question is: How can CMake be used to generate personalized commands like tar? I would like to see some code samples. For the full functionality it would be useful to create project's components and be able to use them as parameters. (Exempli gratia: archive only header files or some specific library). Thanks in advance for your answers!

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  • Copy a function in memory and execute it

    - by Elinghton
    Hi everybody, I would like to know how in C in can copy the content of a function into memroy and the execute it? I'm trying to do something like this: typedef void(*FUN)(int *); char * myNewFunc; char *allocExecutablePages (int pages) { template = (char *) valloc (getpagesize () * pages); if (mprotect (template, getpagesize (), PROT_READ|PROT_EXEC|PROT_WRITE) == -1) { perror ("mprotect"); } } void f1 (int *v) { *v = 10; } // allocate enough spcae but how much ?? myNewFunc = allocExecutablePages(...) /* Copy f1 somewere else * (how? assume that i know the size of f1 having done a (nm -S foo.o)) */ ((FUN)template)(&val); printf("%i",val); Thanks for your answers

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  • MySql "comments" parameter as descriptor?

    - by Nick
    So, I'm trying to learn a lot at once, and this place is really helpful! I'm making a little running log website for myself and maybe a few other people, and I have it so that the user can add workouts for each day. With each workout, I have a variety of information the user can fill out for the workout, such as running distance, time, quality of run, course, etc... I store this in a MySql database as a table with fields titled "distance", "time", "runquality", etc... Now, these field titles don't match up with what I want displayed on the running log, so I was thinking of using the "Comments" attribute for a field to store its human-readable title--thus the field "runquality" would have "Quality of run" as its comment, and then I would pull the comment with a SQL query and display it instead of the field name. Is this a good theoretical/practical way of going about it? And what sort of SQL would I use to pull the comment for the field anyway? Secondly, suppose I want to add the ability for the user to create their own workout descriptors. So say a user wants to add a "temperature" descriptor for their workout. Should I create a script that adds fields to my workout table, or should I create a separate table listing only workout descriptors and somehow link the descriptor table with the "contents" table? I haven't learned any theory about database design or anything so any help is appreciated!

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  • Doubt about constructor in JAVA

    - by Harry Joy
    I have few doubts regarding constructor in java Can a constructor be private? If yes then in which condition? Constructor is a method or not? If constructor does not return anything then why we are getting a new Object every time we call it. Whats the default access modifier of a constructor if we did not specify. Thanks & Regards Edit---------- Answer for 1 & 3 are very clear. But still doubt about 2&4 as i'm getting different answers for them.

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  • Performance of: if (OBJECT_INSTANCE is TYPE)

    - by Axonn
    I am working both in C# and ActionScript 3. Both language are type-aware, so you can do verifications such as: if (some_object_instance is SomeClassName_ThatIs_SomeType) I'm doing these kind of verifications in a few places. Might be a dumb question, but I will ask it anyway, and I want answers from both camps, C# and ActionScript: What goes on behind the scenes? Is it Reflection? If is, isn't this a long verification which might degrade performance if done in thousands of loops? And by "degrade performance" I mean, is it more intensive than say if (Math.sqrt(8) > Math.sin(10))

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  • What is the worst real-world macros/pre-processor abuse you've ever come across?

    - by Trevor Boyd Smith
    What is the worst real-world macros/pre-processor abuse you've ever come across (please no contrived IOCCC answers *haha*)? Please add a short snippet or story if it is really entertaining. The goal is to teach something instead of always telling people "never use macros". p.s.: I've used macros before... but usually I get rid of them eventually when I have a "real" solution (even if the real solution is inlined so it becomes similar to a macro). Bonus: Give an example where the macro was really was better than a not-macro solution. Related question: When are C++ macros beneficial?

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  • Learn Prolog Now! DCG Practice Example

    - by Timothy
    I have been progressing through Learn Prolog Now! as self-study and am now learning about Definite Clause Grammars. I am having some difficulty with one of the Practical Session's tasks. The task reads: The formal language anb2mc2mdn consists of all strings of the following form: an unbroken block of as followed by an unbroken block of bs followed by an unbroken block of cs followed by an unbroken block of ds, such that the a and d blocks are exactly the same length, and the c and d blocks are also exactly the same length and furthermore consist of an even number of cs and ds respectively. For example, ε, abbccd, and aaabbbbccccddd all belong to anb2mc2mdn. Write a DCG that generates this language. I am able to write rules that generate andn, b2mc2m, and even anb2m and c2mndn... but I can't seem to join all these rules into anb2mc2mdn. The following are my rules that can generate andn and b2mc2m. s1 --> []. s1 --> a,s1,d. a --> [a]. d --> [d]. s2 --> []. s2 --> c,c,s2,d,d. c --> [c]. d --> [d]. Is anb2mc2mdn really a CFG, and is it possible to write a DCG using only what was taught in the lesson (no additional arguments or code, etc)? If so, can anyone offer me some guidance how I can join these so that I can solve the given task?

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  • API For Flex Apps To Interact

    - by dimo414
    I have a large flex application (the app) running on one server, and many small flex applications (widgets) running on another server, which are to be included in the app so that visually the user see's one continuous application. Due to proprietary third party software, this structure cannot be changed. I am looking for some way to allow the app and the widgets to communicate, allowing the app to make changes to the widgets and the the widgets to notify the app when events are triggered, so that user interaction is fluid and continuous. There are a few related questions which indicate it's possible to do this by setting up event triggers and listeners. I am wondering if there is any standardized way to do this (the answers aren't very clear) or if anyone has developed a library or API to make this easier.

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  • ssrs 2008 programmatically add tables rows

    - by davethecoder
    Above is how my report looks, the part in yellow in hidden, and is only shown when the user clicks the + icon on the [name]. the result is basically the percentage difference from the Past [X] - [TERM] i.e there is a dropdown with, [weeks, months, days, hours] and a textbox of qty. so choosing qty = 4 and term = weeks will delivery a result set spread over 4 weeks based on the parent result sets date range and name ID I wish to populate here the number of rows, dependant on the value set by the user and the data will be from a dataset. Is it possible to dynamically add more sub rows ( like on row data bound ) if my first row is ID 123 [name], is it possible to send this value [123] to a dataset in order that all subrows are only relevant to the name with ID of 123? this is my first bash at SSRS so please no half cut answers, that just lead to more questions about the answer given :-) if this makes sense. Thanks

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  • iphone web app: open directions in external maps application

    - by munchybunch
    I've seen the answers for opening the Maps app in a native iPhone app, but is there any way to do this in a web app? I've tried changing window.location to http://maps.google.com/maps?q=cupertino for example, to no avail. I've tried using a simple anchor tag linked to http://maps.google.com/maps?q=cupertino, also to no avail. Has anyone gotten this to work before? I'm working on a map-heavy application, and I'd like to provide users with directions at the end. I figured it would be easiest to simply open it up in the Map application. Note: I'm currently testing with just the simulator, could that lead to problems? My iPhone is down for the count at the moment.

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  • MSBuild syntax for deleting files/directories and reporting what was deleted

    - by Maslow
    Vs2010 .net 4.0 targeted project if that affects the answers at all. I want to delete the bin and obj directories and output a message for the path of what was deleted. <Target Name="CleanOutputs" Condition="'$(MvcBuildViews)'=='true'"> <Message Text="Cleaning Outputs" Importance="high"/> <RemoveDir Directories="$(OutputPath);obj" RemovedDirectories="@(removed)" /> <Message Text="Removed: %(removed.FullPath)" Importance="high"/> <Message Text=" "/> <!--<RemoveDir Directories="obj" />--> <MakeDir Condition="!Exists('$(OutputPath)')" Directories="$(OutputPath)" /> </Target> Is what I have, but the Removed: message never shows.

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  • How can I change standart input/output of another program?

    - by Azad Salahli
    I have a console application written in c++. It simply reads an integer from standard input(keyboard) and writes another integer to standard output(screen). Now I want to give some tests to that program and check its answers using another program. In another words, I want to write electron judge for that program. I want that program(which I want to test) to read from file and write to file without changing source code. How can I do that. I tried assigning input&output to files before executing c++ program, but it did not worked. assign(input,'temp.in'); reset(input); assign(output,'temp.out'); rewrite(output); exec('domino.exe'); close(input); close(output);

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  • Displaying a collection of objects in a .Net grid on a smartphone without data binding.

    - by Xav
    I know there's No DataGridView in the CF, but I've got a collection of in-memory objects that I want to display in a grid on a phone. Options I have thought of: Stick all the objects into a SQL-CE database and use a bound datagrid. This'll mean pulling my classes apart and separating the data from the functionality, which may or may not be a bad thing, but seems a little overkill. Write my own dataset and binding code so that I can bind my collection of objects to a bound datagrid. No idea how practical or possible this is, but seems like it's either do-able or impossible and I'm hoping someone here knows which! Find a third-party unbound grid control. The only one I've seen mentioned is OpenNetCF, which I'm downloading as I type. Are there others? Are any of them any good? Do something very nasty with dynamically loading labels and textboxes into a scrolling region on the form. REALLY don't want to go there. I'm not much experienced with data-bound controls other than occasionally making use of the very vanilla functionality in WinForms or ASP.Net, and that quite a long time ago, so if any of the above are silly, please be gentle. Thanks Xav

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  • start page with questions about interested tags?

    - by Stefan K.
    I'm new to stackoverflow and I'm looking for a question list, like the one on top, which just contains questions about interested tags. For example I'm interested in Java, but I have no clue about Python and questions about python clutters my questions page. I don't have answers concerning any python problem. I think it's too exhausting to enter my interested tags in the search combined with [xxx] OR. Is there a usable way to do this? By the way, what for are interested tags used right now? I added some in my profile but didn't see a benefit.

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  • Data Warehouse: One Database or many?

    - by drrollins
    At my new company, they keep all data associated with the data warehouse, including import, staging, audit, dimension and fact tables, together in the same physical database. I've been a database developer for a number of years now and this consolidation of function and form seems counter to everything I know. It seems to make security, backup/restore and performance management issues more manually intensive. Is this something that is done in the industry? Are there substantial reasons for doing or not doing it? The platform is Netezza. The size is in terabytes, hundreds of millions of rows. What I'm looking to get from answers to this question is a solid understanding of how right or wrong this path is. From your experience, what are the issues I should be focused on arguing if this is a path that will cause trouble for us down the road. If it is no big deal, then I'd like to know that as well.

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  • Help with concept - filters and number of items

    - by dreamer
    Please check http://www.alibaba.com/catalogs/cid/702/Laptops.html they have nice filter here with number of items for each. Note one detail - they have locations here. Same thing on olx.com - location and number of items for each category. Now imagine I have tables: [products] (Id, Name, CategoryId, LocationId) [Categories] (Id,Name) [Location] (Id, Name) My question how can I do the same, cause count things even with caching looks expensive? And they give results pretty fast... Please advice with possible ways to do that in ASP.NET, C#, MVC, MS SQL, but avoice simple answers like "count and change" Thank you in advance.

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