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• Recursive N-way merge/diff algorithm for directory trees?

  - by BobMcGee

  What algorithms or Java libraries are available to do N-way, recursive diff/merge of directories? I need to be able to generate a list of folder trees that have many identical files, and have subdirectories with many similar files. I want to be able to use 2-way merge operations to quickly remove as much redundancy as possible. Goals: Find pairs of directories that have many similar files between them. Generate short list of directory pairs that can be synchronized with 2-way merge to eliminate duplicates Should operate recursively (there may be nested duplicates of higher-level directories) Run time and storage should be O(n log n) in numbers of directories and files Should be able to use an embedded DB or page to disk for processing more files than fit in memory (100,000+). Optional: generate an ancestry and change-set between folders Optional: sort the merge operations by how many duplicates they can elliminate I know how to use hashes to find duplicate files in roughly O(n) space, but I'm at a loss for how to go from this to finding partially overlapping sets between folders and their children. EDIT: some clarification The tricky part is the difference between "exact same" contents (otherwise hashing file hashes would work) and "similar" (which will not). Basically, I want to feed this algorithm at a set of directories and have it return a set of 2-way merge operations I can perform in order to reduce duplicates as much as possible with as few conflicts possible. It's effectively constructing an ancestry tree showing which folders are derived from each other. The end goal is to let me incorporate a bunch of different folders into one common tree. For example, I may have a folder holding programming projects, and then copy some of its contents to another computer to work on it. Then I might back up and intermediate version to flash drive. Except I may have 8 or 10 different versions, with slightly different organizational structures or folder names. I need to be able to merge them one step at a time, so I can chose how to incorporate changes at each step of the way. This is actually more or less what I intend to do with my utility (bring together a bunch of scattered backups from different points in time). I figure if I can do it right I may as well release it as a small open source util. I think the same tricks might be useful for comparing XML trees though.

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• Inference engine to calculate matching set according to internal rules

  - by Zecrates

  I have a set of objects with attributes and a bunch of rules that, when applied to the set of objects, provides a subset of those objects. To make this easier to understand I'll provide a concrete example. My objects are persons and each has three attributes: country of origin, gender and age group (all attributes are discrete). I have a bunch of rules, like "all males from the US", which correspond with subsets of this larger set of objects. I'm looking for either an existing Java "inference engine" or something similar, which will be able to map from the rules to a subset of persons, or advice on how to go about creating my own. I have read up on rule engines, but that term seems to be exclusively used for expert systems that externalize the business rules, and usually doesn't include any advanced form of inferencing. Here are some examples of the more complex scenarios I have to deal with: I need the conjunction of rules. So when presented with both "include all males" and "exclude all US persons in the 10 - 20 age group," I'm only interested in the males outside of the US, and the males within the US that are outside the 10 - 20 age group. Rules may have different priorities (explicitly defined). So a rule saying "exclude all males" will override a rule saying "include all US males." Rules may be conflicting. So I could have both an "include all males" and an "exclude all males" in which case the priorities will have to settle the issue. Rules are symmetric. So "include all males" is equivalent to "exclude all females." Rules (or rather subsets) may have meta rules (explicitly defined) associated with them. These meta rules will have to be applied in any case that the original rule is applied, or if the subset is reached via inferencing. So if a meta rule of "exclude the US" is attached to the rule "include all males", and I provide the engine with the rule "exclude all females," it should be able to inference that the "exclude all females" subset is equivalent to the "include all males" subset and as such apply the "exclude the US" rule additionally. I can in all likelihood live without item 5, but I do need all the other properties mentioned. Both my rules and objects are stored in a database and may be updated at any stage, so I'd need to instantiate the 'inference engine' when needed and destroy it afterward.

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• iPhone reachability checking

  - by Sneakyness

  I've found several examples of code to do what I want (check for reachability), but none of it seems to be exact enough to be of use to me. I can't figure out why this doesn't want to play nice. I have the reachability.h/m in my project, I'm doing #import <SystemConfiguration/SystemConfiguration.h> And I have the framework added. I also have: #import "Reachability.h" at the top of the .m in which I'm trying to use the reachability. Reachability* reachability = [Reachability sharedReachability]; [reachability setHostName:@"http://www.google.com"]; // set your host name here NetworkStatus remoteHostStatus = [reachability remoteHostStatus]; if(remoteHostStatus == NotReachable) {NSLog(@"no");} else if (remoteHostStatus == ReachableViaWiFiNetwork) {NSLog(@"wifi"); } else if (remoteHostStatus == ReachableViaCarrierDataNetwork) {NSLog(@"cell"); } This is giving me all sorts of problems. What am I doing wrong? I'm an alright coder, I just have a hard time when it comes time to figure out what needs to be put where to enable what I want to do, regardless if I want to know what I want to do or not. (So frustrating) Update: This is what's going on. This is in my viewcontroller, which I have the #import <SystemConfiguration/SystemConfiguration.h> and #import "Reachability.h" set up with. This is my least favorite part of programming by far. FWIW, we never ended up implementing this in our code. The two features that required internet access (entering the sweepstakes, and buying the dvd), were not main features. Nothing else required internet access. Instead of adding more code, we just set the background of both internet views to a notice telling the users they must be connected to the internet to use this feature. It was in theme with the rest of the application's interface, and was done well/tastefully. They said nothing about it during the approval process, however we did get a personal phone call to verify that we were giving away items that actually pertained to the movie. According to their usually vague agreement, you aren't allowed to have sweepstakes otherwise. I would also think this adheres more strictly to their "only use things if you absolutely need them" ideaology as well. Here's the iTunes link to the application, EvoScanner.

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• How do I integrate a new MVC C# Project with an existing Web Forms VB.NET Web Application Project?

  - by Jordan Rieger

  We have a corporate website with a large amount of dynamic business application pages (e.g. Shopping Cart, Helpdesk, Product/Service management, Reporting, etc.) The site was built as an ASP.Net Web Application Project (WAP). Our systems have evolved over the years to use .NET 4.5 and various custom business logic DLLs (written in a mix of C# and VB.NET). However, the site itself is still using VB.NET Web Forms. We now have done a few side projects in MVC 4 using Razor/C#, and we want to use this framework for new pages on the main corporate site going forward. What would be the easiest way to achieve this? I found this nice list of steps to integrate MVC 4 into an existing Web Forms app. The problem is that because our existing app is a VB.NET WAP, it compiles into a single DLL, and .NET allows only one language per DLL. The site is way too big for us to contemplate converting it to C# all at once (yes, I've looked at the conversion tools, and they're good, but even 99% accuracy would leave us a huge amount of cleanup work.) I thought about converting the existing WAP into a Web Site Project (WSP) which does allow mixing languages and then following the steps above, but after a few pages of Google results, I couldn't find any steps for converting a WAP to WSP. (Plenty of sites offer the reverse steps: converting a WSP to a WAP.) Another idea I had was to create a completely separate MVC project, and then somehow squish them together into the same folder structure, where they would share the bin folder but compile to separate DLL's. I have no idea if this is possible, because certain files would collide (e.g. Global.asax, web.config, etc.) Finally, I can imagine a compromise solution where we keep all the MVC stuff in its own separate application under a subfolder of the main solution. We already use our own custom session state solution, so it wouldn't be difficult to pass data between the old site to the new pages. Which of the ideas above do you think makes the most sense for us? Is there another solution that I'm missing?

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• Middleware with generic communication media layer

  - by Tom

  Greetings all, I'm trying to implement middleware (driver) for an embedded device with generic communication media layer. Not sure what is the best way to do it so I'm seeking an advice from more experienced stackoverflow users:). Basically we've got devices around the country communicating with our servers (or a pda/laptop in used in field). Usual form of communication is over TCP/IP, but could be also using usb, RF dongle, IR, etc. The plan is to have object corresponding with each of these devices, handling the proprietary protocol on one side and requests/responses from other internal systems on the other. The thing is how create something generic in between the media and the handling objects. I had a play around with the TCP dispatcher using boost.asio but trying to create something generic seems like a nightmare :). Anybody tried to do something like that? What is the best way how to do it? Example: Device connects to our Linux server. New middleware instance is created (on the server) which announces itself to one of the running services (details are not important). The service is responsible for making sure that device's time is synchronized. So it asks the middleware what is the device's time, driver translates it to device language (protocol) and sends the message, device responses and driver again translates it for the service. This might seem as a bit overkill for such a simple request but imagine there are more complex requests which the driver must translate, also there are several versions of the device which use different protocol, etc. but would use the same time sync service. The goal is to abstract the devices through the drivers to be able to use the same service to communicate with them. Another example: we find out that the remote communications with the device are down. So we send somebody out with PDA, he connects to the device using USB cable. Starts up the application which has the same functionality as the timesync service. Again middleware instance is created (on the PDA) to translate communication between application and the device this time only using USB/serial media not TCP/IP as in previous example. I hope it makes more sense now :) Cheers, Tom

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• What is a good platform for building a game framework targetting both web and native languages?

  - by fuzzyTew

  I would like to develop (or find, if one is already in development) a framework with support for accelerated graphics and sound built on a system flexible enough to compile to the following: native ppc/x86/x86_64/arm binaries or a language which compiles to them javascript actionscript bytecode or a language which compiles to it (actionscript 3, haxe) optionally java I imagine, for example, creating an API where I can open windows and make OpenGL-like calls and the framework maps this in a relatively efficient manner to either WebGL with a canvas object, 3d graphics in Flash, OpenGL ES 2 with EGL, or desktop OpenGL in an X11, Windows, or Cocoa window. I have so far looked into these avenues: Building the game library in haXe Pros: Targets exist for php, javascript, actionscript bytecode, c++ High level, object oriented language Cons: No support for finally{} blocks or destructors, making resource cleanup difficult C++ target does not allow room for producing highly optimized libraries -- the foreign function interface requires all primitive types be boxed in a wrapper object, as if writing bindings for a scripting language; these feel unideal for real-time graphics and audio, especially exporting low-level functions. Doesn't seem quite yet mature Using the C preprocessor to create a translator, writing programs entirely with macros Pros: CPP is widespread and simple to use Cons: This is an arduous task and probably the wrong tool for the job CPP implementations differ widely in support for features (e.g. xcode cpp has no variadic macros despite claiming C99 compliance) There is little-to-no room for optimization in this route Using llvm's support for multiple backends to target c/c++ to web languages Pros: Can code in c/c++ LLVM is a very mature highly optimizing compiler performing e.g. global inlining Targets exist for actionscript (alchemy) and javascript (emscripten) Cons: Actionscript target is closed source, unmaintained, and buggy. Javascript targets do not use features of HTML5 for appropriate optimization (e.g. linear memory with typed arrays) and are immature An LLVM target must convert from low-level bytecode, so high-level constructs are lost and bloated unreadable code is created from translating individual instructions, which may be more difficult for an unprepared JIT to optimize. "jump" instructions cause problems for languages with no "goto" statements. Using libclang to write a translator from C/C++ to web languages Pros: A beautiful parsing library providing easy access to the code structure Can code in C/C++ Has sponsored developer effort from Apple Cons: Incomplete; current feature set targets IDEs. Basic operators are unexposed and must be manually parsed from the returned AST element to be identified. Translating code prior to compilation may forgo optimizations assumed in c/c++ such as inlining. Creating new code generators for clang to translate into web languages Pros: Can code in C/C++ as libclang Cons: There is no API; code structure is unstable A much larger job than using libclang; the innards of clang are complex Building the game library in Common Lisp Pros: Flexible, ancient, well-developed language Extensive introspection should ease writing translators Translators exist for at least javascript Cons: Unfamiliar language No standardized library functions, widely varying implementations Which of these avenues should I pursue? Do you know of any others, or any systems that might be useful? Does a general project like this exist somewhere already? Thank you for any input.

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• Algorithm for finding symmetries of a tree

  - by Paxinum

  I have n sectors, enumerated 0 to n-1 counterclockwise. The boundaries between these sectors are infinite branches (n of them). The sectors live in the complex plane, and for n even, sector 0 and n/2 are bisected by the real axis, and the sectors are evenly spaced. These branches meet at certain points, called junctions. Each junction is adjacent to a subset of the sectors (at least 3 of them). Specifying the junctions, (in pre-fix order, lets say, starting from junction adjacent to sector 0 and 1), and the distance between the junctions, uniquely describes the tree. Now, given such a representation, how can I see if it is symmetric wrt the real axis? For example, n=6, the tree (0,1,5)(1,2,4,5)(2,3,4) have three junctions on the real line, so it is symmetric wrt the real axis. If the distances between (015) and (1245) is equal to distance from (1245) to (234), this is also symmetric wrt the imaginary axis. The tree (0,1,5)(1,2,5)(2,4,5)(2,3,4) have 4 junctions, and this is never symmetric wrt either imaginary or real axis, but it has 180 degrees rotation symmetry if the distance between the first two and the last two junctions in the representation are equal. Edit: This is actually for my research. I have posted the question at mathoverflow as well, but my days in competition programming tells me that this is more like an IOI task. Code in mathematica would be excellent, but java, python, or any other language readable by a human suffices. Here are some examples (pretend the double edges are single and we have a tree) http://www2.math.su.se/~per/files.php?file=contr_ex_1.pdf http://www2.math.su.se/~per/files.php?file=contr_ex_2.pdf http://www2.math.su.se/~per/files.php?file=contr_ex_5.pdf Example 1 is described as (0,1,4)(1,2,4)(2,3,4)(0,4,5) with distances (2,1,3). Example 2 is described as (0,1,4)(1,2,4)(2,3,4)(0,4,5) with distances (2,1,1). Example 5 is described as (0,1,4,5)(1,2,3,4) with distances (2). So, given the description/representation, I want to find some algorithm to decide if it is symmetric wrt real, imaginary, and rotation 180 degrees. The last example have 180 degree symmetry. (These symmetries corresponds to special kinds of potential in the Schroedinger equation, which has nice properties in quantum mechanics.)

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• How to do a search from a list with non-prefix keywords[Solved]

  - by aNui

  The Problem is Solved. Thanks for every answers. First of all, sorry if my english or my post got any mistakes. I am programming a program to search the name from the list and I need to find them even if the keyword is not in front of the names (that's what I mean non-prefix) e.g. if I my list is the music instruments and I type "guit" to the search textbox. It should find the names "Guitar, Guitarrón, Acoustic Guitar, Bass Guitar, ..." or something like this Longdo Dictionary's search suggestion. here is my simple and stupid algorithm (that's all I can do) const int SEARCHROWLIMIT = 30; private string[] DoSearch(string Input, string[] ListToSearch) { List<string> FoundNames = new List<string>(); int max = 0; bool over = false; for (int k = 0; !over; k++) { foreach (string item in ListToSearch) { max = (max > item.Length) ? max : item.Length; if (k > item.Length) continue; if (k >= max) { over = true; break; } if (!Input.Equals("Search") && item.Substring(k, item.Length - k).StartsWith(Input, StringComparison.OrdinalIgnoreCase)) { bool exist = false; int i = 0; while (!exist && i < FoundNames.Count) { if (item.Equals(FoundNames[i])) { exist = true; break; } i++; } if (!exist && FoundNames.Count < SEARCHROWLIMIT) FoundNames.Add(item); else if (FoundNames.Count >= SEARCHROWLIMIT) over = true; } } } return FoundNames.ToArray(); } I think this algorithm is too slow for a large number of names and after several trial-and-error, I decided to add SEARCHROWLIMIT to breaks the operation And I also think there're some readymade methods that can do that. And another problem is I need to search music instruments by a category like strings, percussions, ... and by the country of origins. So I need to search them with filter by type and country. please help me. P.S. Me and my friends are just student from Thailand and developing the project to compete in Microsoft Imagine Cup 2010 and please become fan on our facebook page [KRATIB][3]. And we're so sorry we don't have much information in English but you can talk to us in English.

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• compiling a program to run in DOS mode

  - by dygi

  I write a simple program, to run in DOS mode. Everything works under emulated console in Win XP / Vista / Seven, but not in DOS. The error says: this program caonnot be run in DOS mode. I wonder is that a problem with compiler flags or something bigger. For programming i use Code::Blocks v 8.02 with such settings for compilation: -Wall -W -pedantic -pedantic-errors in Project \ Build options \ Compiler settings I've tried a clean DOS mode, booting from cd, and also setting up DOS in Virtual Machine. The same error appears. Should i turn on some more compiler flags ? Some specific 386 / 486 optimizations ? UPDATE Ok, i've downloaded, installed and configured DJGPP. Even resolved some problems with libs and includes. Still have two questions. 1) i can't compile a code, which calls _strdate and _strtime, i've double checked the includes, as MSDN says it needs time.h, but still error says: _strdate was not declared in this scope, i even tried to add std::_strdate, but then i have 4, not 2 errors sazing the same 2) the 2nd code is about gotoxy, it looks like that: #include <windows.h> void gotoxy(int x, int y) { COORD position; position.X = x; position.Y = y; SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), position); } error says there is no windows.h, so i've put it in place, but then there are many more errors saying some is missing from windows.h, I SUPPOSE it won't work because this functions is strictly for windows right ? is there any way to write similar gotoxy for DOS ? UPDATE2 1) solved using time(); instead of _strdate(); and _strtime(); here's the code time_t rawtime; struct tm * timeinfo; char buffer [20]; time ( &rawtime ); timeinfo = localtime ( &rawtime ); strftime (buffer,80,"%Y.%m.%d %H:%M:%S\0",timeinfo); string myTime(buffer); It now compiles under DJGPP. UPDATE3 Still need to solve a code using gotoxy - replaced it with some other code that compiles (under DJGPP). Thank You all for help. Just learnt some new things about compiling (flags, old IDE's like DJGPP, OpenWatcom) and refreshed memories setting DOS to work :--)

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• What facets have I missed for creating a 3 person guerilla dev team?

  - by Penguinix

  Sorry for the Windows developers out there, this solution is for Macs only. This set of applications accounts for: Usability Testing, Screen Capture (Video and Still), Version Control, Task Lists, Bug Tracking, a Developer IDE, a Web Server, A Blog, Shared Doc Editing on the Web, Team and individual Chat, Email, Databases and Continuous Integration. This does assume your team members provide their own machines, and one person has a spare old computer to be the Source Repository and Web Server. All for under $200 bucks. Usability Silverback Licenses = 3 x $49.95 "Spontaneous, unobtrusive usability testing software for designers and developers." Source Control Server and Clients (multiple options) Subversion = Free Subversion is an open source version control system. Versions (Currently in Beta) = Free Versions provides a pleasant work with Subversion on your Mac. Diffly = Free "Diffly is a tool for exploring Subversion working copies. It shows all files with changes and, clicking on a file, shows a highlighted view of the changes for that file. When you are ready to commit Diffly makes it easy to select the files you want to check-in and assemble a useful commit message." Bug/Feature/Defect Tracking (multiple options) Bugzilla = Free Bugzilla is a "Defect Tracking System" or "Bug-Tracking System". Defect Tracking Systems allow individual or groups of developers to keep track of outstanding bugs in their product effectively. Most commercial defect-tracking software vendors charge enormous licensing fees. Trac = Free Trac is an enhanced wiki and issue tracking system for software development projects. Database Server & Clients MySQL = Free CocoaMySQL = Free Web Server Apache = Free Development and Build Tools XCode = Free CruiseControl = Free CruiseControl is a framework for a continuous build process. It includes, but is not limited to, plugins for email notification, Ant, and various source control tools. A web interface is provided to view the details of the current and previous builds. Collaboration Tools Writeboard = Free Ta-da List = Free Campfire Chat for 4 users = Free WordPress = Free "WordPress is a state-of-the-art publishing platform with a focus on aesthetics, web standards, and usability. WordPress is both free and priceless at the same time." Gmail = Free "Gmail is a new kind of webmail, built on the idea that email can be more intuitive, efficient, and useful." Screen Capture (Video / Still) Jing = Free "The concept of Jing is the always-ready program that instantly captures and shares images and video…from your computer to anywhere." Lots of great responses: TeamCity [Yo|||] Skype [Eric DeLabar] FogBugz [chakrit] IChatAV and Screen Sharing (built-in to OS) [amrox] Google Docs [amrox]

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• What's the standard algorithm for syncing two lists of objects?

  - by Oliver Giesen

  I'm pretty sure this must be in some kind of text book (or more likely in all of them) but I seem to be using the wrong keywords to search for it... :( A common task I'm facing while programming is that I am dealing with lists of objects from different sources which I need to keep in sync somehow. Typically there's some sort of "master list" e.g. returned by some external API and then a list of objects I create myself each of which corresponds to an object in the master list. Sometimes the nature of the external API will not allow me to do a live sync: For instance the external list might not implement notifications about items being added or removed or it might notify me but not give me a reference to the actual item that was added or removed. Furthermore, refreshing the external list might return a completely new set of instances even though they still represent the same information so simply storing references to the external objects might also not always be feasible. Another characteristic of the problem is that both lists cannot be sorted in any meaningful way. You should also assume that initializing new objects in the "slave list" is expensive, i.e. simply clearing and rebuilding it from scratch is not an option. So how would I typically tackle this? What's the name of the algorithm I should google for? In the past I have implemented this in various ways (see below for an example) but it always felt like there should be a cleaner and more efficient way. Here's an example approach: Iterate over the master list Look up each item in the "slave list" Add items that do not yet exist Somehow keep track of items that already exist in both lists (e.g. by tagging them or keeping yet another list) When done iterate once more over the slave list Remove all objects that have not been tagged (see 4.) Update Thanks for all your responses so far! I will need some time to look at the links. Maybe one more thing worthy of note: In many of the situations where I needed this the implementation of the "master list" is completely hidden from me. In the most extreme cases the only access I might have to the master list might be a COM-interface that exposes nothing but GetFirst-, GetNext-style methods. I'm mentioning this because of the suggestions to either sort the list or to subclass it both of which is unfortunately not practical in these cases unless I copy the elements into a list of my own and I don't think that would be very efficient. I also might not have made it clear enough that the elements in the two lists are of different types, i.e. not assignment-compatible: Especially, the elements in the master list might be available as interface references only.

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• Passing Objects between different files

  - by user309779

  Typically, if I want to pass an object to an instance of something I would do it like so... Listing 1 File 1: public class SomeClass { // Some Properties public SomeClass() { public int ID { get { return mID; } set { mID = value; } } public string Name { set { mName = value; } get { return mName; } } } } public class SomeOtherClass { // Method 1 private void Method1(int one, int two) { SomeClass USER; // Create an instance Squid RsP = new Squid(); RsP.sqdReadUserConf(USER); // Able to pass 'USER' to class method in different file. } } In this example, I was not able to use the above approach. Probably because the above example passes an object between classes. Whereas, below, things are defined in a single class. I had to use some extra steps (trial & error) to get things to work. I am not sure what I did here or what its called. Is it good programming practice? Or is there is an easier way to do this (like above). Listing 2 File 1: private void SomeClass1 { [snip] TCOpt_fM.AutoUpdate = optAutoUpdate.Checked; TCOpt_fM.WhiteList = optWhiteList.Checked; TCOpt_fM.BlackList = optBlackList.Checked; [snip] private TCOpt TCOpt_fM; TCOpt_fM.SaveOptions(TCOpt_fM); } File 2: public class TCOpt: { public TCOpt OPTIONS; [snip] private bool mAutoUpdate = true; private bool mWhiteList = true; private bool mBlackList = true; [snip] public bool AutoUpdate { get { return mAutoUpdate; } set { mAutoUpdate = value; } } public bool WhiteList { get { return mWhiteList; } set { mWhiteList = value; } } public bool BlackList { get { return mBlackList; } set { mBlackList = value; } } [snip] public bool SaveOptions(TCOpt OPTIONS) { [snip] Some things being written out to a file here [snip] Squid soSwGP = new Squid(); soSgP.sqdWriteGlobalConf(OPTIONS); } } File 3: public class SomeClass2 { public bool sqdWriteGlobalConf(TCOpt OPTIONS) { Console.WriteLine(OPTIONS.WhiteSites); // Nothing prints here Console.WriteLine(OPTIONS.BlackSites); // Or here } } Thanks in advance, XO

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• Would a Centralized Blogging Service Work?

  - by viatropos

  If there's a better place to ask this, please let me know. Every time I build a new website/blog/shopping-cart/etc., I keep trying to do the following: Extract out common functionality into reusable code (Rubygems and jQuery plugins mostly) If possible, convert that gem into a small service so I never have to deal with a database for the objects involved (by service, I mean something lean and mean, usually built with the Sinatra Web Framework with a few core models. My assumption is, if I can remove dependencies on local databases, that will make it easier and more scalable in the long run (scalable in terms of reusability and manageability, not necessarily database/performance). I'm not sure if that's a good or bad assumption yet. What do you think? I've made this assumption because of the following reason: Most serious database/model functionality has been built on the internet somewhere. Just to name a few: Social Network API: Facebook Messaging API: Twitter Mailing API: Google Event API: Eventbrite Shopping API: Shopify Comment API: Disqus Form API: Wufoo Image API: Picasa Video API: Youtube ... Each of those things are fairly complicated to build from scratch and to make as optimized, simple, and easy to use as those companies have. So if I build an app that shows pictures (picasa) on an Event page (eventbrite), and you can see who joined the event (facebook events), and send them emails (google apps api), and have them fill out monthly surveys (wufoo), and watch a video when they're done (youtube), all integrated into a custom, easy to use website, and I can do that without ever creating a local database, is that a good thing? I ask because there's two things missing from the puzzle that keep forcing me to create that local database: Post API RESTful/Pretty Url API While there's plenty of Blogging systems and APIs for them, there is no one place where you can just write content and have it part of some massive thing. For every app, I have to use code for creating pretty/restful urls, and that saves posts. But it seems like that should be a service! Question is, is that the main point of a website? Will everyone always need "their own blog"? Why not just have a profile and write lots of content on an established platform like StackOverflow or Facebook?

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• Can I call make runtime decided method calls in Java?

  - by Catalin Marin

  I know there is an invoke function that does the stuff, I am overall interested in the "correctness" of using such a behavior. My issue is this: I have a Service Object witch contains methods which I consider services. What I want to do is alter the behavior of those services without later intrusion. For example: class MyService { public ServiceResponse ServeMeDonuts() { do stuff... return new ServiceResponse(); } after 2 months I find out that I need to offer the same service to a new client app and I also need to do certain extra stuff like setting a flag, or make or updating certain data, or encode the response differently. What I can do is pop it up and throw down some IFs. In my opinion this is not good as it means interaction with tested code and may result in un wanted behaviour for the previous service clients. So I come and add something to my registry telling the system that the "NewClient" has a different behavior. So I'll do something like this: public interface Behavior { public void preExecute(); public void postExecute(); } public class BehaviorOfMyService implements Behavior{ String method; String clientType; public void BehaviorOfMyService(String method,String clientType) { this.method = method; this.clientType = clientType; } public void preExecute() { Method preCall = this.getClass().getMethod("pre" + this.method + this.clientType); if(preCall != null) { return preCall.invoke(); } return false; } ...same for postExecute(); public void preServeMeDonutsNewClient() { do the stuff... } } when the system will do something like this if(registrySaysThereIs different behavior set for this ServiceObject) { Class toBeCalled = Class.forName("BehaviorOf" + usedServiceObjectName); Object instance = toBeCalled.getConstructor().newInstance(method,client); instance.preExecute(); ....call the service... instance.postExecute(); .... } I am not particularly interested in correctness of code as in correctness of thinking and approach. Actually I have to do this in PHP, witch I see as a kind of Pop music of programming which I have to "sing" for commercial reasons, even though I play POP I really want to sing by the book, so putting aside my more or less inspired analogy I really want to know your opinion on this matter for it's practical necessity and technical approach. Thanks

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• Do Websites need Local Databases Anymore?

  - by viatropos

  If there's a better place to ask this, please let me know. Every time I build a new website/blog/shopping-cart/etc., I keep trying to do the following: Extract out common functionality into reusable code (Rubygems and jQuery plugins mostly) If possible, convert that gem into a small service so I never have to deal with a database for the objects involved (by service, I mean something lean and mean, usually built with the Sinatra Web Framework with a few core models). My assumption is, if I can remove dependencies on local databases, that will make it easier and more scalable in the long run (scalable in terms of reusability and manageability, not necessarily database/performance). I'm not sure if that's a good or bad assumption yet. What do you think? I've made this assumption because of the following reason: Most serious database/model functionality has been built on the internet somewhere. Just to name a few: Social Network API: Facebook Messaging API: Twitter Mailing API: Google Event API: Eventbrite Shopping API: Shopify Comment API: Disqus Form API: Wufoo Image API: Picasa Video API: Youtube ... Each of those things are fairly complicated to build from scratch and to make as optimized, simple, and easy to use as those companies have made them. So if I build an app that shows pictures (picasa) on an Event page (eventbrite), and you can see who joined the event (facebook events), and send them emails (google apps api), and have them fill out monthly surveys (wufoo), and watch a video when they're done (youtube), all integrated into a custom, easy to use website, and I can do that without ever creating a local database, is that a good thing? I ask because there's two things missing from the puzzle that keep forcing me to create that local database: Post API RESTful/Pretty Url API While there's plenty of Blogging systems and APIs for them, there is no one place where you can just write content and have it part of some massive thing. For every app, I have to use code for creating pretty/restful urls, and that saves posts. But it seems like that should be a service! Question is, is that what the website is? ...That place to integrate the worlds services for my specific cause... and, sigh, to store posts that only my site has access to. Will everyone always need "their own blog"? Why not just have a profile and write lots of content on an established platform like StackOverflow or Facebook? ... That way I can write apps entirely without a database and know that I'm doing it right. Note: Of course at some point you'd need a database, if you were doing something unique or new. But for the case where you're just rewiring information or creating things like videos, events, and products, is it really necessary anymore??

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• Malformed Farsi characters on AWT

  - by jlover2010

  Hi As i started programming by jdk6, i had no problem in text components neither in awt nor in swing. But for labels or titles of awt components, yes : I couldn't have Farsi characters displayable on AWTs just as simple as Swing by typing them into the source code. lets check this SSCCE : import javax.swing.*; import java.awt.*; import java.io.*; import java.util.Properties; public class EmptyFarsiCharsOnAWT extends JFrame{ public EmptyFarsiCharsOnAWT() { super("????"); setDefaultCloseOperation(3); setVisible(rootPaneCheckingEnabled); } public static void main(String[] args) throws AWTException, IOException { JFrame jFrame = new EmptyFarsiCharsOnAWT(); MenuItem show ; // approach 1 = HardCoding : /* show = new MenuItem("\u0646\u0645\u0627\u06cc\u0634"); * */ // approach 2 = using simple utf-8 saved text file : /* BufferedReader in = new BufferedReader(new FileReader("farsiLabels.txt")); String showLabel = in.readLine(); in.close(); show = new MenuItem(showLabel); * */ // approach 3 = using properties file : FileReader in = new FileReader("farsiLabels.properties"); Properties farsiLabels = new Properties(); farsiLabels.load(in); show = new MenuItem(farsiLabels.getProperty("tray.show")); PopupMenu popUp = new PopupMenu(); popUp.add(show); // creating Tray object Image iconIamge = Toolkit.getDefaultToolkit().getImage("greenIcon.png"); TrayIcon trayIcon = new TrayIcon(iconIamge, null, popUp); SystemTray tray = SystemTray.getSystemTray(); tray.add(trayIcon); jFrame.setIconImage(iconIamge); } } Yes, i know each of three approaches in source code does right when you may test it from IDE , but if you make a JAR contains just this class, by means of NetBeans project clean&build ,you won't see the expected characters and will just get EMPTY/BLANK SQUARES ! Unfortunately, opposed to other situations i encountered before, here there is no way to avoid using awt and make use of Swing in this case. And this was just an SSCCE i made to show the problem and my recent (also first) application suffers from this subject. Note: it seems i can not attach anything, so the contents od the text file would be this: ????? and the contents of properties file: #Sun May 02 09:45:10 IRDT 2010 tray.show=????? but i don't think by giving you the unicode-scape sequence, these would be necessary any way... And i think should have to let you know I posted this question a while ago in SDN and "the Java Ranch" forums and other native forums and still I'm watching... By the way i am using latest version of Netbeans IDE... I will be so grateful if anybody has a solution to this damn AWT components never rendered any Farsi character for me... Thanks in advance

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• Windows 7 - pydoc from cmd

  - by Random_Person

  Okay, I'm having one of those moments that makes me question my ability to use a computer. This is not the sort of question I imagined asking as my first SO post, but here goes. Started on Zed's new "Learn Python the Hard Way" since I've been looking to get back into programming after a 10 year hiatus and python was always what I wanted. This book has really spoken to me. That being said, I'm having a serious issue with pydoc from the command. I've got all the directories in c:/python26 in my system path and I can execute pydoc from the command line just fine regardless of pwd - but it accepts no arguments. Doesn't matter what I type, I just get the standard pydoc output telling me the acceptable arguments. Any ideas? For what it's worth, I installed ActivePython as per Zed's suggestion. C:\Users\Chevee>pydoc file pydoc - the Python documentation tool pydoc.py <name> ... Show text documentation on something. <name> may be the name of a Python keyword, topic, function, module, or package, or a dotted reference to a class or function within a module or module in a package. If <name> contains a '\', it is used as the path to a Python source file to document. If name is 'keywords', 'topics', or 'modules', a listing of these things is displayed. pydoc.py -k <keyword> Search for a keyword in the synopsis lines of all available modules. pydoc.py -p <port> Start an HTTP server on the given port on the local machine. pydoc.py -g Pop up a graphical interface for finding and serving documentation. pydoc.py -w <name> ... Write out the HTML documentation for a module to a file in the current directory. If <name> contains a '\', it is treated as a filename; if it names a directory, documentation is written for all the contents. C:\Users\Chevee> EDIT: New information, pydoc works just fine in PowerShell. As a linux user, I have no idea why I'm trying to use cmd anyways--but I'd still love to figure out what's up with pydoc and cmd. EDIT 2: More new information. In cmd... c:\>python c:/python26/lib/pydoc.py file ...works just fine. Everything works just fine with just pydoc in PowerShell without me worrying about pwd, or extensions or paths.

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• Square Peg Web: Gets you the traffic to where it matters most: Your Website!

  - by demetriusalwyn

  Have you decided to start your business online or is your business not reaching the targeted audience? Come to Square Peg Web; where you will find what you want to make your business reach new heights. The team at Square Peg Web is professionals who understand what you want and make sure you get it right. Our confidence stems from the fact of thousands of satisfied clients who keep referring friends and business associates to us and we do not let our clients down. Many companies promise the sky but how far is does their work live up to the promises? We do not know about the others however, we are sure that we strive to put together all our ideas and thoughts to make your website rank among the top. Web hosting is something that needs to have a personal touch; Square Peg Web customizes everything to suit your requirements so that you do not have to look further. With Square Peg Web you have a host of features to make your Business go viral. Some of the product details that are offered with Square Peg Web are unlimited product options/ variants/ properties giving you an option on price modifiers. You get unlimited customized input fields for your products and you can also Customer-define the prices. Square Peg Web provides you an option of using multiple product images with zoom features and one can also list a particular product in several categories. There are other aspects which make Square Peg Web the best choice for your website needs; every sale of yours’ is important to you and to us. We make sure that each sale is tracked by the product and also the list of bestsellers that appeal to the audience. Other comprehensive statistics of Square Peg Web includes searchable order data, an interface for shipments and order fulfillments, export sales & customer data for usage in a spreadsheet and the ability to export orders to QuickBooks format. With Square Peg Web; Admin Panel is a lot simpler. Administrative access is completely password protected and any changes done are all in real-time. You can have absolute control on the cart from anywhere around the world using your web browser and the topping on the cake is the unlimited amount of admin accounts that can be created for you. Square Peg Web offers you a world of experience with the options of choosing from marketing websites to e-commerce and from customized applications to community oriented sites. Some of the projects which appear in the portfolio of Square Peg Web are Online Marketing Web Sites, E-Commerce Web Sites, customized web applications, Blog designing and programming, video sharing and the option of downloading web sites, online advertisements, flash animation, customer and product support web sites, web site re-designing and planning and complete information architecture.

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• NHibernate : delete error

  - by MadSeb

  Hi, Model: I have a model in which one Installation can contain multiple "Computer Systems". Database: The table Installations has two columns Name and Description. The table ComputerSystems has three columsn Name, Description and InstallationId. Mappings: I have the following mapping for Installation: <?xml version="1.0" encoding="utf-8"?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="myProgram.Core" namespace="myProgram"> <class name="Installation" table="Installations" lazy="true"> <id name="Id" column="Id" type="int"> <generator class="native" /> </id> <property name="Name" column="Name" type="string" not-null="true" /> <property name="Description" column="Description" type="string" /> <bag name="ComputerSystems" inverse="true" lazy="true" cascade="all-delete-orphan"> <key column="InstallationId" /> <one-to-many class="ComputerSystem" /> </bag> </class> </hibernate-mapping> I have the following mapping for ComputerSystem: <?xml version="1.0" encoding="utf-8"?> <id name="Id" column="ID" type="int"> <generator class="native" /> </id> <property name="Name" column="Name" type="string" not-null="true" /> <property name="Description" column="Description" type="string" /> <many-to-one name="Installation" column="InstallationID" cascade="save-update" not-null="true" /> Classes: The Installation class is: public class Installation { public virtual String Description { get; set; } public virtual String Name { get; set; } public virtual IList<ComputerSystem> ComputerSystems { get { if (_computerSystemItems== null) { lock (this) { if (_computerSystemItems== null) _computerSystemItems= new List<ComputerSystem>(); } } return _computerSystemItems; } set { _computerSystemItems= value; } } protected IList<ComputerSystem> _computerSystemItems; public Installation() { Description = ""; Name= ""; } } The ComputerSystem class is: public class ComputerSystem { public virtual String Name { get; set; } public virtual String Description { get; set; } public virtual Installation Installation { get; set; } } The issue is that I get an error when trying to delete an installation that contains a ComputerSystem. The error is: "deleted object would be re-saved by cascade (remove deleted object from associations)". Can anyone help ? Regards, Seb

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• How can I remove rows with unique values? As in only keeping rows with duplicate values?

  - by user1456405

  Here's the conundrum, I'm a complete and utter noob when it comes to programming. I understand the basics, but am still learning javascript. I have a spreadsheet of surveys, in which I need to see how particular users have varied over time. As such, I need to disregard all rows with unique values in a particular column. The data looks like this: Response Date Response_ID Account_ID Q.1 10/20/2011 12:03:43 PM 23655956 1168161 8 10/20/2011 03:52:57 PM 23660161 1168152 0 10/21/2011 10:55:54 AM 23672903 1166121 7 10/23/2011 04:28:16 PM 23694471 1144756 9 10/25/2011 06:30:52 AM 23732674 1167449 7 10/25/2011 07:52:28 AM 23734597 1087618 5 I've found a way to do so in VBA, which sucks as I have to use excel, per below: Sub Del_Unique() Application.ScreenUpdating = False Columns("B:B").Insert Shift:=xlToRight Columns("A:A").Copy Destination:=Columns("B:B") i = Application.CountIf(Range("A:A"), "<>") + 50 If i > 65536 Then i = 65536 Do If Application.CountIf(Range("B:B"), Range("A" & i)) = 1 Then Rows(i).Delete End If i = i - 1 Loop Until i = 0 Columns("B:B").Delete Application.ScreenUpdating = True End Sub But that requires mucking about. I'd really like to do it in Google Spreadsheets with a script that won't have to be changed. Closest I can get is retrieving all duplicate user ids from the range, but can't associate that with the row. That code follows: function findDuplicatesInSelection() { var activeRange = SpreadsheetApp.getActiveRange(); var values = activeRange.getValues(); // values that appear at least once var once = {}; // values that appear at least twice var twice = {}; // values that appear at least twice, stored in a pretty fashion! var final = []; for (var i = 0; i < values.length; i++) { var inner = values[i]; for (var j = 0; j < inner.length; j++) { var cell = inner[j]; if (cell == "") continue; if (once.hasOwnProperty(cell)) { if (!twice.hasOwnProperty(cell)) { final.push(cell); } twice[cell] = 1; } else { once[cell] = 1; } } } if (final.length == 0) { Browser.msgBox("No duplicates found"); } else { Browser.msgBox("Duplicates are: " + final); } } Anyhow, sorry if this is the wrong place or format, but half of what I've found so far has been from stack, I thought it was a good place to start. Thanks!

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• Strange behaviour of NSString in NSView

  - by Mee

  Trying to create a Skat-Game, I encountered the following problem: isBidding is a Boolean value indicationg, the program is in a certain state, [desk selected] is a method calling returning the current selected player, chatStrings consists of dictionaries, saving strings with the player, who typed, and what he typed - (void)drawRect:(NSRect)rect { NSMutableDictionary * attributes = [NSMutableDictionary dictionary]; [attributes setObject:[NSFont fontWithName:playerFont size:playerFontSize] forKey:NSFontAttributeName]; [attributes setObject:playerFontColor forKey:NSForegroundColorAttributeName]; [[NSString stringWithFormat:@"Player %i",[desk selected] + 1]drawInRect:playerStringRect withAttributes:attributes]; if (isBidding) { [attributes setObject:[NSFont fontWithName:chatFont size:chatFontSize] forKey:NSFontAttributeName]; [attributes setObject:chatFontColor forKey:NSForegroundColorAttributeName]; int i; for (i = 0; i < [chatStrings count]; i++, yProgress -= 20) { if (isBidding) [[NSString stringWithFormat:@"Player %i bids: %@",[[[chatStrings objectAtIndex:i]valueForKey:@"Player"]intValue], [[chatStrings objectAtIndex:i]valueForKey:@"String"]] drawAtPoint:NSMakePoint([self bounds].origin.x, yProgress) withAttributes:attributes]; else [[NSString stringWithFormat:@"Player %i: %@",[[[chatStrings objectAtIndex:i]valueForKey:@"Player"]intValue], [[chatStrings objectAtIndex:i]valueForKey:@"String"]] drawAtPoint:NSMakePoint([self bounds].origin.x, yProgress) withAttributes:attributes]; } if (isBidding) [[NSString stringWithFormat:@"Player %i bids: %@",[desk selected] + 1, displayString] drawAtPoint:NSMakePoint([self bounds].origin.x, yProgress) withAttributes:attributes]; else [[NSString stringWithFormat:@"Player %i: %@",[desk selected] + 1, displayString] drawAtPoint:NSMakePoint([self bounds].origin.x, yProgress) withAttributes:attributes]; yProgress = chatFontBegin; } } This is the part determining the string's content, the string is contributed by an [event characters] method. -(void)displayChatString:(NSString *)string { displayString = [displayString stringByAppendingString:string]; [self setNeedsDisplay:YES]; } The problem if have is this: when typing in more than two letters the view displays NSRectSet{{{471, 574},{500, 192}}} and returns no more discription when I try to print it. then I get an EXC_BAD_ACCESS message, though I have not released it (as far as I can see) I also created the string with alloc and init, so I cannot be in the autorelease pool. I also tried to watch the process when it changes with the debugger, but I couldn't find any responsible code. As you can see I am still a beginner in Cocoa (and programming in general), so I would be really happy if somebody would help me with this.

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• Can GPU capabilities impact virtual machine performance?

  - by Dave White

  While this many not seem like a programming question directly, it impacts my development activities and so it seems like it belongs here. It seems that more and more developers are turning to virtual environments for development activities on their computers, SharePoint development being a prime example. Also, as a trainer, I have virtual training environments for all of the classes that I teach. I recently purchased a new Dell E6510 to travel around with. It has the i7 620M (Dual core, HyperThreaded cpu running at 2.66GHz) and 8 GB of memory. Reading the spec sheet, it sounded like it would be a great laptop to carry around and run virtual machines on. Getting the laptop though, I've been pretty disappointed with the user experience of developing in a virtual machine. Giving the Virtual Machine 4 GB of memory, it was slow and I could type complete sentences and watch the VM "catchup". My company has training laptops that we provide for our classes. They are Dell Precision M6400 Intel Core 2 Duo P8700 running at 2.54Ghz with 8 GB of memory and the experience on this laptops is night and day compared to the E6510. They are crisp and you barely aware that you are running in a virtual environment. Since the E6510 should be faster in all categories than the M6400, I couldn't understand why the new laptop was slower, so I did a component by component comparison and the only place where the E6510 is less performant than the M6400 is the graphics department. The M6400 is running a nVidia FX 2700m GPU and the E6510 is running a nVidia 3100M GPU. Looking at benchmarks of the two GPUs suggest that the FX 2700M is twice as fast as the 3100M. http://www.notebookcheck.net/Mobile-Graphics-Cards-Benchmark-List.844.0.html 3100M = 111th (E6510) FX 2700m = 47th (Precision M6400) Radeon HD 5870 = 8th (Alienware) The host OS is Windows 7 64bit as is the guest OS, running in Virtual Box 3.1.8 with Guest Additions installed on the guest. The IDE being used in the virtual environment is VS 2010 Premium. So after that long setup, my question is: Is the GPU significantly impacting the virtual machine's performance or are there other factors that I'm not looking at that I can use to boost the vm's performance? Do we now have to consider GPU performance when purchasing laptops where we expect to use virtualized development environments? Thanks in advance. Cheers, Dave

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• Checking to see if a number is evenly divisible by other numbers with recursion in Python

  - by Ernesto

  At the risk of receiving negative votes, I will preface this by saying this is a midterm problem for a programming class. However, I have already submitted the code and passed the question. I changed the name of the function(s) so that someone can't immediately do a search and find the correct code, as that is not my purpose. I am actually trying to figure out what is actually MORE CORRECT from two pieces that I wrote. The problem tells us that a certain fast food place sells bite-sized pieces of chicken in packs of 6, 9, and 20. It wants us to create a function that will tell if a given number of bite-sized piece of chicken can be obtained by buying different packs. For example, 15 can be bought, because 6 + 9 is 15, but 16 cannot be bought, because no combination of the packs will equal 15. The code I submitted and was "correct" on, was: def isDivisible(n): """ n is an int Returns True if some integer combination of 6, 9 and 20 equals n Otherwise returns False. """ a, b, c = 20, 9, 6 if n == 0: return True elif n < 0: return False elif isDivisible(n - a) or isDivisible(n - b) or isDivisible(n - c): return True else: return False However, I got to thinking, if the initial number is 0, it will return True. Would an initial number of 0 be considered "buying that amount using 6, 9, and/or 20"? I cannot view the test cases the grader used, so I don't know if the grader checked 0 as a test case and decided that True was an acceptable answer or not. I also can't just enter the new code, because it is a midterm. I decided to create a second piece of code that would handle an initial case of 0, and assuming 0 is actually False: def isDivisible(n): """ n is an int Returns True if some integer combination of 6, 9 and 20 equals n Otherwise returns False. """ a, b, c = 20, 9, 6 if n == 0: return False else: def helperDivisible(n): if n == 0: return True elif n < 0: return False elif helperDivisible(n - a) or helperDivisible(n - b) or helperDivisible(n - c): return True else: return False return helperDivisible(n) As you can see, my second function had to use a "helper" function in order to work. My overall question, though, is which function do you think would provide the correct answer, if the grader had tested for 0 as an initial input?

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• Can you help me optimize this code for finding factors of a number? I'm brushing up on my math progr

  - by Sergio Tapia

  I've never really bothered with math programming, but today I've decided to give it a shot. Here's my code and it's working as intended: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Imaging; using System.Windows.Navigation; using System.Windows.Shapes; namespace PrimeFactorization { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); } private void btnSubmit_Click(object sender, RoutedEventArgs e) { List<int> primeFactors = FindPrimeFactors(Convert.ToInt32(txtNumber.Text)); primeFactors.Sort(); for (int i = 0; i < primeFactors.Count; i++) { listBoxFoundNumbers.Items.Add(primeFactors[i]); } } private List<int> FindPrimeFactors(int number) { List<int> factors = new List<int>(); factors.Add(1); factors.Add(number); for (int i = 2; i < number; i++) { if (number % i == 0) { int holder = number / i; //If the number is in the list, don't add it again. if (!factors.Contains(i)) { factors.Add(i); } //If the number is in the list, don't add it again. if (!factors.Contains(holder)) { factors.Add(holder); } } } return factors; } } } The only problem I can see with my code is that it will iterate through to the bitter end, even though there will definitely not be any factors. For example, imagine I wrote in 35. My loop will go up to 35 and check 24,25,26,27...etc. Not very good. What do you recommend?

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• The Math of a Jump in a 2D game.

  - by ONi

  I have been all around with this question and I can't find the correct answer! So, behold, the description of my question: I'm working in J2ME, I have my gameloop that do the following: public void run() { Graphics g = this.getGraphics(); while (running) { long diff = System.currentTimeMillis() - lastLoop; lastLoop = System.currentTimeMillis(); input(); this.level.doLogic(); render(g, diff); try { Thread.sleep(10); } catch (InterruptedException e) { stop(e); } } } so it's just a basic gameloop, the doLogic() function calls for all the logic functions of the characters in the scene and render(g, diff) calls the animateChar function of every character on scene, following this, the animChar function in the Character class sets up everything in the screen as this: protected void animChar(long diff) { this.checkGravity(); this.move((int) ((diff * this.dx) / 1000), (int) ((diff * this.dy) / 1000)); if (this.acumFrame > this.framerate) { this.nextFrame(); this.acumFrame = 0; } else { this.acumFrame += diff; } } This ensures me that everything must to move according to the time that the machine takes to go from cycle to cycle (remember it's a phone, not a gaming rig). I'm sure it's not the most efficient way to achieve this behavior so I'm totally open for criticism of my programming skills in the comments, but here my problem: When I make I character jump, what I do is that I put his dy to a negative value, say -200 and I set the boolean jumping to true, that makes the character go up, and then I have this function called checkGravity() that ensure that everything that goes up has to go down, checkGravity also checks for the character being over platforms so I will strip it down a little for the sake of your time: public void checkGravity() { if (this.jumping) { this.jumpSpeed += 10; if (this.jumpSpeed > 0) { this.jumping = false; this.falling = true; } this.dy = this.jumpSpeed; } if (this.falling) { this.jumpSpeed += 10; if (this.jumpSpeed > 200) this.jumpSpeed = 200; this.dy = this.jumpSpeed; if (this.collidesWithPlatform()) { this.falling = false; this.standing = true; this.jumping = false; this.jumpSpeed = 0; this.dy = this.jumpSpeed; } } } So, the problem is, that this function updates the dy regardless of the diff, making the characters fly like Superman in slow machines, and I have no idea how to implement the diff factor so that when a character is jumping, his speed decrement in a proportional way to the game speed. Can anyone help me fix this issue? or give me pointers on how to make a 2D Jump in J2ME the right way. Thank you very much for your time.

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