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  • Binary files printing and desired precision

    - by yCalleecharan
    Hi, I'm printing a variable say z1 which is a 1-D array containing floating point numbers to a text file so that I can import into Matlab or GNUPlot for plotting. I've heard that binary files (.dat) are smaller than .txt files. The definition that I currently use for printing to a .txt file is: void create_out_file(const char *file_name, const long double *z1, size_t z_size){ FILE *out; size_t i; if((out = _fsopen(file_name, "w+", _SH_DENYWR)) == NULL){ fprintf(stderr, "***> Open error on output file %s", file_name); exit(-1); } for(i = 0; i < z_size; i++) fprintf(out, "%.16Le\n", z1[i]); fclose(out); } I have three questions: Are binary files really more compact than text files?; If yes, I would like to know how to modify the above code so that I can print the values of the array z1 to a binary file. I've read that fprintf has to be replaced with fwrite. My output file say dodo.dat should contain the values of array z1 with one floating number per line. I have %.16Le up in my code but I think that %.15Le is right as I have 15 precision digits with long double. I have put a dot (.) in the width position as I believe that this allows expansion to an arbitrary field to hold the desired number. Am I right? As an example with %.16Le, I can have an output like 1.0047914240730432e-002 which gives me 16 precision digits and the width of the field has the right width to display the number correctly. Is placing a dot (.) in the width position instead of a width value a good practice? Thanks a lot...

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  • What MS technology to use for HTTP service returning XML?

    - by Borek
    I need to create a service that: accepts HTTP requests (with query string or HTTP POST parameters) does some processing on the requests (checking if the request is valid, authentication etc.) reads data from a custom store (another HTTP call in our case) returns the result as custom XML (defined with XSD) I'm trying to think of various MS technologies that could help me and how good they would be for this scenario (pretty standard one I guess). The tasks above are relatively separate, this is what comes to mind: HTTP front-end: ASP.NET Web Forms ASP.NET MVC (seems more appropriate here as I won't need server controls, view state etc.) WCF? Don't know much about it or how well it would suit my task. Custom logic on the server: this will probably be a generic C# code in all cases (sometimes "plugged into" or called from MVC controllers or some equivalent place in other technologies) Reading data from internal data stores: As said, this is another HTTP server in our case. Options that come to mind: Just read the data using something like WebClient (Just theoretically) implement a LINQ provider (Just even more theoretically) implement an EF provider Output the data as custom XML: Linq2XML Serialization? Is it flexible enough? Does WCF provide some tools for this? Some "OXM" - Object/XML mapper if there is something like that for .NET I may be wrong in many of my assumptions, this is just a quick list that comes to mind after a quick research. Some general notes / questions: Testing is important Solution with a clear domain model would be much preferred over the one without Can Entity Framework actually help somewhere in my scenario? If so, where and how? Would WCF be an appropriate technology for this? I don't know much about it.

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  • Accomplishing This Style of Drop-Down Menus in jQuery

    - by Maxim Z.
    I was browsing the web and found this site. I noticed how the nav bar drop-down works, and I want to implement something similar on my website. Afer going into the source code of the page, I found that those drop-down areas are contained in divs with class fOut. It turns out that this is being done with MooTools. Here is the script itself (referenced in the original page after the Mootools script itself): window.addEvent('domready', function() { $("primaryNav").getChildren("li").addEvents({ "mouseenter": function(){ $(this).addClass("hover").getChildren("a").addClass("hover"); }, "mouseleave": function(){ $(this).removeClass("hover").getChildren("a").removeClass("hover"); } }); $$(".fOut").each(function(el,i){ var ifr = $(document.createElement("iframe")); ifr.className = "ieBgIframe"; ifr.frameBorder = "0"; ifr.src="about:blank"; ifr.injectInside(el); var p = el.getParent(); p.addClass("hover"); var h = el.getSize().size.y; p.removeClass("hover"); ifr.height=h; }); $$(".olderVersionsToggle").addEvents({ "click": function(e){ var event = new Event(e); event.stop(); var p = $(this).getParent().getNext(); if(p.hasClass("open")){ p.removeClass("open"); $(this).setText("Show previous versions..."); } else{ p.addClass("open"); $(this).setText("Hide previous versions..."); } return false; } }); }); My Question(s) I have two questions about this code. How does it work? I don't quite understand what it's doing, with the iframes and all. How can this be implemented in jQuery?

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  • How do you make a static sprite be a child of another sprite in cocos2D while using SpaceManager

    - by JJBigThoughts
    I have two static (STATIC_MASS) SpaceManager sprites. One is a child of the other - by which I mean that one sort of builds up the other one, but although the child's images shows up in the right place, the child doesn't seem to exists in the chipmunk physics engine, like I would expect. In my case, I have a backboard (rectangular sprite) and a hoop (a circular sprite). Since I might want to move the backboard, I'd like to attach the hoop to backboard so that the hoop automatically moves right along with the backboard. Here, we see a rotating backboard with attached hoop. It looks OK on the screen, but other objects only bounce off the backboard but pass right through the hoop (in a bad sense of the term). What doesn't my child sprite seem to exist in the physics engine? // Add Backboard cpShape *shapeRect = [smgr addRectAt:cpvWinCenter mass:STATIC_MASS width:200 height:10 rotation:0.0f ];// We're upgrading this cpCCSprite * cccrsRect = [cpCCSprite spriteWithShape:shapeRect file:@"rect_200x10.png"]; [self addChild:cccrsRect]; // Spin the static backboard: http://stackoverflow.com/questions/2691589/how-do-you-make-a-sprite-rotate-in-cocos2d-while-using-spacemanager // Make static object update moves in chipmunk // Since Backboard is static, and since we're going to move it, it needs to know about spacemanager so its position gets updated inside chipmunk. // Setting this would make the smgr recalculate all static shapes positions every step // cccrsRect.integrationDt = smgr.constantDt; // cccrsRect.spaceManager = smgr; // Alternative method: smgr.rehashStaticEveryStep = YES; smgr.rehashStaticEveryStep = YES; // Spin the backboard [cccrsRect runAction:[CCRepeatForever actionWithAction: [CCSequence actions: [CCRotateTo actionWithDuration:2 angle:180], [CCRotateTo actionWithDuration:2 angle:360], nil] ]]; // Add the hoop cpShape *shapeHoop = [smgr addCircleAt:ccp(100,-45) mass:STATIC_MASS radius: 50 ]; cpCCSprite * cccrsHoop = [cpCCSprite spriteWithShape:shapeHoop file:@"hoop_100x100.png"]; [cccrsRect addChild:cccrsHoop]; This is only half working for me. Note: SpaceManager is a toolkit for working with cocos2D-iphone

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  • Advanced Linq query using into

    - by dilbert789
    I have this query that someone else wrote, it's over my head so I'm looking for some direction. What is happening currently is that it's taking numbers where there is a goal and no history entered, or history and no goal, this screws up the calculations as both goal and history for the same item are required on each. The three tables involved are: KPIType Goal KPIHistory What I need: Need all rows from KPIType. Need all goals where there is a matching KPIHistory row (Goal.KPItypeID == KPIHistory.KPItypeID ) into results 1 Need all kpiHistory’s where there is a matching Goal row (Goal.KPItypeID == KPIHistory.KPItypeID ) into results 2 Current query: var query = from t in dcs.KPIType.Where(k => k.ID <= 23) join g in dcs.Goal.Where(g => g.Dealership.ID == dealershipID && g.YearMonth >= beginDate && g.YearMonth <= endDate ) on t.ID equals g.KPITypeID into results1 join h in dcs.KPIHistory.Where(h => h.Dealership.ID == dealershipID && h.ForDate >= beginDate && h.ForDate <= endDate ) on t.ID equals h.KPIType.ID into results2 orderby t.DisplayOrder select new { t, Goal = results1, KPIHistory = results2 }; query.ToList().ForEach(q => { results.Add(q.t); }); Thanks, I'm happy to answer questions if more info needed.

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  • Mutex example / tutorial ?

    - by Nav
    I've noticed that asking questions for the sake of creating a reference list etc. is encouraged in SO. This is one such question, so that anyone Googling for a mutex tutorial will find a good one here. I'm new to multithreading, and was trying to understand how mutexes work. Did a lot of Googling and this is the only decent tutorial I found, but it still left some doubts of how it works because I created my own program and the locking didn't work. One absolutely non-intuitive syntax of the mutex is pthread_mutex_lock( &mutex1 );, where it looks like the mutex is being locked, when what I really want to lock is some other variable. Does this syntax mean that locking a mutex locks a region of code until the mutex is unlocked? Then how do threads know that the region is locked? And isn't such a phenomenon supposed to be called critical section? In short, could you please help with the simplest possible mutex example program and the simplest possible explanation on the logic of how it works? I'm sure this will help plenty of other newbies.

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  • How do I ensure my C# software can access the internet in a Citrix + ISA environment?

    - by TomFromThePool
    Hi everyone, A client recently informed us that deployment of our software in their environment has failed due to a proxy error when the software attempts to access the internet. The client has a combination of Citrix and Microsoft's ISA server. The software allows the use of a proxy and the ability to manually enter authentication information, or automatically retrieve the current system proxy settings. The error returned is the standard 407 authentication error, but the client assures us that they have entered the authentication information required. They have also shown us the snippet of the ISA error logs which identify the client as Anonymous and the authentication protocol as Basic. I have a few questions I suppose: How should I go about dealing with the ISA server in my code? I have no real experience with this environment and am assuming that the ISA server is treated like any other proxy. If I am mistaken, what should I be doing? Does ISA allow the administrator to disallow specific authentication protocols - and if this is the case and 'Basic' auth is disallowed, would it still return a 407 error? Could the Citrix environment have caused this issue? Is there any particular way to ensure that my software will work in such an environment? Code-samples would be much appreciated. I have neither a Citrix test server or an ISA server at my disposal to carry out testing on this so I am currently trying to identify possible causes before I make the case for investment in a more robust testing environment. Thanks for any help!

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  • Return enum instead of bool from function for clarity ?

    - by Moe Sisko
    This is similar to : http://stackoverflow.com/questions/2908876/net-bool-vs-enum-as-a-method-parameter but concerns returning a bool from a function in some situations. e.g. Function which returns bool : public bool Poll() { bool isFinished = false; // do something, then determine if finished or not. return isFinished; } Used like this : while (!Poll()) { // do stuff during wait. } Its not obvious from the calling context what the bool returned from Poll() means. It might be clearer in some ways if the "Poll" function was renamed "IsFinished()", but the method does a bit of work, and (IMO) would not really reflect what the function actually does. Names like "IsFinished" also seem more appropriate for properties. Another option might be to rename it to something like : "PollAndReturnIsFinished" but this doesn't feel right either. So an option might be to return an enum. e.g : public enum Status { Running, Finished } public Status Poll() { Status status = Status.Running; // do something, then determine if finished or not. return status; } Called like this : while (Poll() == Status.Running) { // do stuff during wait. } But this feels like overkill. Any ideas ?

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  • Appropriate SQL Server Permissions for Developers

    - by BJ Safdie
    After a couple of Google searches and a quick look at questions here, I cannot seem to find what I thought would be a cookbook answer for SQL Server permissions. As I often see in small shops, most developers here were using an admin account for SQL Server while developing. I want to set up roles and permissions that I can assign to developers so that we can get our jobs done, but also do so with the minimum permissions required. Can anyone offer advice on what SQL Server permissions to assign? Components: SQL Server 2008 SQL Server Reporting Services (SSRS) 2008 SQL Server Integration Services (SSIS) 2008 Platforms: Production Staging/QA Development/Integration We are running "Mixed Mode" security because of some legacy apps and networks, but are moving to Windows Auth. I am not sure if that really affects the role set up. I plan to set up access for Developers to Prod and Staging/QA DBs as Read-Only. However, I still want developers to retain the ability to run Profiling. We need Deployment accounts with higher privilege levels. We are currently trying to figure out exactly what privileges we need for SSIS package deployments. Within the Development Server, Developers need broad privileges. However, I am not sure that just making them all admins is really the best choice. It's hard to believe that no one has published a decent example script that sets up these kinds of roles with a good set of appropriate permissions for developers and deployers. We can probably figure this all out by locking things down and then adding permissions as we discover the need, but that will be way too big a PITA for everyone. Can anyone point me to, or provide, a good exemplar for permissions for these kinds of roles on these kinds of platforms?

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  • Licensing iPhone apps per user in existing system

    - by Alxandr
    I've been asked by my job to write a iPhone app for an existing system for managing worktasks. This system is proprietary and costs money, so in order to login you need to be a customer. Now, I've got two questions about the legality of licensing iPhone apps with this system: My company would like to be able to sell the app for profit, but not as a one-time payment, but as a added subscription-fee to the already existing one. Is it legal for us (according with the terms of distributing an iPhone app on the Apple App Store) to do this? That way we'll just add another field to the users-database saying weather or not iPhone is enabled for them, and distribute the app as a free app on App Store. If the previous question is not legal, we'd like to just create a free app and distribute it as part of the existing system. In other words, no extra fee for using the iPhone app for the users, but still free distribution trough App Store. Due to our company not being american or having an office in the U.S. at all enterprice account is not an option. Please let me know if there is anything wrong with any of the above approaches.

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  • How to update application files using patching?

    - by Marek
    I am not interested in any auto update solution, such as ClickOnce or the MS Updater Block. For anyone feeling the urge to ask why not: I am already using these and there is nothing wrong with them, I would just like to learn about any efficient alternatives. I would like to publish patches = small differences that will modify existing files of the deployment with the smallest possible delta. Not only code needs to be patched, but also resource files. Patching the running code can be accomplished by maintaining two separate synchronized copies of the deployment (no on the fly changes to the running executable are required). The application itself can be xcopy deployed (to avoid MSI auto-correcting the modified files or breaking ClickOnce signatures). I would like to learn how to handle different versions of patches (e.g. there is a patch issued that fixes one error and later another patch that fixes another error (in the same file) - users may have any combination of these and there comes a third patch - in text files, this may be easy to implement, but how about executable files? (native Win32 code vs. .NET, any difference?) If the first problem is too hard to solve or unsolvable for executables, I would like to at least learn if there is a solution that implements simple patching with serial revisions - in order to install revision 5, user must have all previous revisions installed to ensure validity of the deployment. Are there any existing solutions to accomplish this? NOTE: There are a few questions on SO that may seem like duplicates, but none with a good answer. This question is about the Windows platform, preferably .NET.

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  • How can I get back my privilege to create a new database in MySQL?

    - by Steven
    I can not use MySQL. MySQL is on my local computer. Currently I added skip-grant-tables in My.ini so I can use MySQL. But I have no privilege to create a new database. My problem is tough, although I asked related questions on SO, but no answer can resolve my problem. I almost give up. So I lower my expectation. I am developing a website, so I need to create database, tables and operate tables. You don't have to consider security. Is there a simple solution that can give me privilege to create a new database? Maybe by adding some command in my.ini or something? You won't need to completely resolve my problem. Maybe after the development, I will upload the database and tables to another server(The current database server is my personal computer, windows XP) so I can uninstall and reinstall MySQL. The root of problem is that I lack privileges.

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  • Router 2wire, Slackware desktop in DMZ mode, iptables policy aginst ping, but still pingable

    - by skriatok
    I'm in DMZ mode, so I'm firewalling myself, stealthy all ok, but I get faulty test results from Shields Up that there are pings. Yesterday I couldn't make a connection to game servers work, because ping block was enabled (on the router). I disabled it, but this persists even due to my firewall. What is the connection between me and my router in DMZ mode (for my machine, there is bunch of others too behind router firewall)? When it allows router affecting if I'm pingable or not and if router has setting not blocking ping, rules in my iptables for this scenario do not work. Please ignore commented rules, I do uncomment them as I want. These two should do the job right? iptables -A INPUT -p icmp --icmp-type echo-request -j DROP echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all Here are my iptables: #!/bin/sh # Begin /bin/firewall-start # Insert connection-tracking modules (not needed if built into the kernel). #modprobe ip_tables #modprobe iptable_filter #modprobe ip_conntrack #modprobe ip_conntrack_ftp #modprobe ipt_state #modprobe ipt_LOG # allow local-only connections iptables -A INPUT -i lo -j ACCEPT # free output on any interface to any ip for any service # (equal to -P ACCEPT) iptables -A OUTPUT -j ACCEPT # permit answers on already established connections # and permit new connections related to established ones (eg active-ftp) iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT #Gamespy&NWN #iptables -A INPUT -p tcp -m tcp -m multiport --ports 5120:5129 -j ACCEPT #iptables -A INPUT -p tcp -m tcp --dport 6667 --tcp-flags SYN,RST,ACK SYN -j ACCEPT #iptables -A INPUT -p tcp -m tcp --dport 28910 --tcp-flags SYN,RST,ACK SYN -j ACCEPT #iptables -A INPUT -p tcp -m tcp --dport 29900 --tcp-flags SYN,RST,ACK SYN -j ACCEPT #iptables -A INPUT -p tcp -m tcp --dport 29901 --tcp-flags SYN,RST,ACK SYN -j ACCEPT #iptables -A INPUT -p tcp -m tcp --dport 29920 --tcp-flags SYN,RST,ACK SYN -j ACCEPT #iptables -A INPUT -p udp -m udp -m multiport --ports 5120:5129 -j ACCEPT #iptables -A INPUT -p udp -m udp --dport 6500 -j ACCEPT #iptables -A INPUT -p udp -m udp --dport 27900 -j ACCEPT #iptables -A INPUT -p udp -m udp --dport 27901 -j ACCEPT #iptables -A INPUT -p udp -m udp --dport 29910 -j ACCEPT # Log everything else: What's Windows' latest exploitable vulnerability? iptables -A INPUT -j LOG --log-prefix "FIREWALL:INPUT" # set a sane policy: everything not accepted > /dev/null iptables -P INPUT DROP iptables -P FORWARD DROP iptables -P OUTPUT DROP iptables -A INPUT -p icmp --icmp-type echo-request -j DROP # be verbose on dynamic ip-addresses (not needed in case of static IP) echo 2 > /proc/sys/net/ipv4/ip_dynaddr # disable ExplicitCongestionNotification - too many routers are still # ignorant echo 0 > /proc/sys/net/ipv4/tcp_ecn #ping death echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all # If you are frequently accessing ftp-servers or enjoy chatting you might # notice certain delays because some implementations of these daemons have # the feature of querying an identd on your box for your username for # logging. Although there's really no harm in this, having an identd # running is not recommended because some implementations are known to be # vulnerable. # To avoid these delays you could reject the requests with a 'tcp-reset': #iptables -A INPUT -p tcp --dport 113 -j REJECT --reject-with tcp-reset #iptables -A OUTPUT -p tcp --sport 113 -m state --state RELATED -j ACCEPT # To log and drop invalid packets, mostly harmless packets that came in # after netfilter's timeout, sometimes scans: #iptables -I INPUT 1 -p tcp -m state --state INVALID -j LOG --log-prefix \ "FIREWALL:INVALID" #iptables -I INPUT 2 -p tcp -m state --state INVALID -j DROP # End /bin/firewall-start Active ruleset: bash-4.1# iptables -L -n -v Chain INPUT (policy DROP 38 packets, 2228 bytes) pkts bytes target prot opt in out source destination 0 0 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0 844 542K ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED 38 2228 LOG all -- * * 0.0.0.0/0 0.0.0.0/0 LOG flags 0 level 4 prefix `FIREWALL:INPUT' 0 0 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0 0 0 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED 38 2228 LOG all -- * * 0.0.0.0/0 0.0.0.0/0 LOG flags 0 level 4 prefix `FIREWALL:INPUT' Chain FORWARD (policy DROP 0 packets, 0 bytes) pkts bytes target prot opt in out source destination Chain OUTPUT (policy DROP 0 packets, 0 bytes) pkts bytes target prot opt in out source destination 1158 111K ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 0 0 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 Active ruleset: (after editing iptables into below sugested form) bash-4.1# iptables -L -n -v Chain INPUT (policy DROP 2567 packets, 172K bytes) pkts bytes target prot opt in out source destination 49 4157 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0 412K 441M ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED 2567 172K LOG all -- * * 0.0.0.0/0 0.0.0.0/0 LOG flags 0 level 4 prefix `FIREWALL:INPUT' 0 0 DROP icmp -- * * 0.0.0.0/0 0.0.0.0/0 icmp type 8 Chain FORWARD (policy DROP 0 packets, 0 bytes) pkts bytes target prot opt in out source destination Chain OUTPUT (policy ACCEPT 312K packets, 25M bytes) pkts bytes target prot opt in out source destination ping and syslog simultaneous screenshots from phone (pinger) and from laptop (being pinged) http://dl.dropbox.com/u/4160051/slckwr/pingfrom%20mobile.jpg http://dl.dropbox.com/u/4160051/slckwr/tailsyslog.jpg

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  • Is Google the only OpenID provider that requires "identifier_select"?

    - by Skrat
    I am developing an OpenID consumer in PHP and am using the fantastic LightOpenID library (http://gitorious.org/lightopenid). Basing my code off of that found in the example client script I have successfully created a consumer. However, I've run across a snag: Google requires the openid.identity and openid.claimed_id to be set to "http://specs.openid.net/auth/2.0/identifier_select" (see here). If I do that it works but other providers (i.e. AOL) don't. Here are my questions: Is Google a corner case –– is it the only OpenID provider where identifier_select is required, contrary to the OpenID specs? Is there a shortcoming in the LightOpenID library? Is my understanding of how OpenID works incorrect? If Google is not the only provider that requires identifier_select are there a finite number of them which I'll just hardcode in, or is there someway to determine this through the OpenID spec? I'm new to the internals of OpenID so I wouldn't be surprised if this is a dumb question. I haven't been able to find any info on this subject after scouring the Internet.

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  • C++ Multiple inheritance with interfaces?

    - by umanga
    Greetings all, I come from Java background and I am having difficulty with multiple inheritance. I have an interface called IView which has init() method.I want to derive a new class called PlaneViewer implementing above interface and extend another class. (QWidget). My implementation is as: IViwer.h (only Header file , no CPP file) : #ifndef IVIEWER_H_ #define IVIEWER_H_ class IViewer { public: //IViewer(); ///virtual //~IViewer(); virtual void init()=0; }; #endif /* IVIEWER_H_ */ My derived class. PlaneViewer.h #ifndef PLANEVIEWER_H #define PLANEVIEWER_H #include <QtGui/QWidget> #include "ui_planeviewer.h" #include "IViewer.h" class PlaneViewer : public QWidget , public IViewer { Q_OBJECT public: PlaneViewer(QWidget *parent = 0); ~PlaneViewer(); void init(); //do I have to define here also ? private: Ui::PlaneViewerClass ui; }; #endif // PLANEVIEWER_H PlaneViewer.cpp #include "planeviewer.h" PlaneViewer::PlaneViewer(QWidget *parent) : QWidget(parent) { ui.setupUi(this); } PlaneViewer::~PlaneViewer() { } void PlaneViewer::init(){ } My questions are: Is it necessary to declare method init() in PlaneViewer interface also , because it is already defined in IView? 2.I cannot complie above code ,give error : PlaneViewer]+0x28): undefined reference to `typeinfo for IViewer' collect2: ld returned 1 exit status Do I have to have implementation for IView in CPP file?

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  • Delphi Performance: Case Versus If

    - by Andreas Rejbrand
    I guess there might be some overlapping with previous SO questions, but I could not find a Delphi-specific question on this topic. Suppose that you want to check if an unsigned 32-bit integer variable "MyAction" is equal to any of the constants ACTION1, ACTION2, ... ACTIONn, where n is - say 1000. I guess that, besides being more elegant, case MyAction of ACTION1: {code}; ACTION2: {code}; ... ACTIONn: {code}; end; if much faster than if MyAction = ACTION1 then // code else if MyAction = ACTION2 then // code ... else if MyAction = ACTIONn then // code; I guess that the if variant takes time O(n) to complete (i.e. to find the right action) if the right action ACTIONi has a high value of i, whereas the case variant takes a lot less time (O(1)?). Am I correct that switch is much faster? Am I correct that the time required to find the right action in the switch case actually is independent of n? I.e. is it true that it does not really take any longer to check a million cases than to check 10 cases? How, exactly, does this work?

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  • What are the worst examples of moral failure in the history of software engineering?

    - by Amanda S
    Many computer science curricula include a class or at least a lecture on disasters caused by software bugs, such as the Therac-25 incidents or Ariane 5 Flight 501. Indeed, Wikipedia has a list of software bugs with serious consequences, and a question on StackOverflow addresses some of them too. We study the failures of the past so that we don't repeat them, and I believe that rather than ignoring them or excusing them, it's important to look at these failures squarely and remind ourselves exactly how the mistakes made by people in our profession cost real money and real lives. By studying failures caused by uncaught bugs and bad process, we learn certain lessons about rigorous testing and accountability, and we make sure that our innocent mistakes are caught before they cause major problems. There are kinds of less innocent failure in software engineering, however, and I think it's just as important to study the serious consequences caused by programmers motivated by malice, greed, or just plain amorality. Thus we can learn about the ethical questions that arise in our profession, and how to respond when we are faced with them ourselves. Unfortunately, it's much harder to find lists of these failures--the only one I can come up with is that apocryphal "DOS ain't done 'til Lotus won't run" story. What are the worst examples of moral failure in the history of software engineering?

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  • Migrating a Large amount of data from old publishing site to new site

    - by tommizzle
    Hi, I am currently in the process of creating a new news/publishing site on the Movable Type platform. There are around 20 or so sites with 20,000+ rows of data to be moved/aggregated to ~8 sites (we have a number of location specific sites and are going to aggregate the content from these into 1 single site for each niche). We have discussed how to do this and came to the conclusion that it would probably be better to hire somebody to do it (I could probably do it, but i'm limited on time and am sure that a specialist would be more efficient). So my questions to you guys are: 1) What kind of skill set should we look for in an applicant? 2) There will be a large amount of input from our side... is getting somebody to work remotely out of the question? 3) How long would a task like this traditionally take (I know this question is very subjective, but an estimation would be awesome)? 4) Do you have any recommendations for firms who would be able to take on a large task like this? Thanks in advance, Tom

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  • AS3 variables handling by AVM/compiler/scope

    - by jchmielewski
    I have couple of questions about AS3 variables handling by AVM/compiler/scope .1. This code in Flash will throw an error: function myFunction() { var mc:MovieClip=new MovieClip(); var mc:MovieClip=new MovieClip(); } but it won`t throw an error in Flex (only warning in Editor). Why? .2. How Flash sees variables in loops? Apparently this: for (var i:int=0; i<2; i++) { var mc:MovieClip=new MovieClip(); } isn`t equal to just: var mc:MovieClip=new MovieClip(); var mc:MovieClip=new MovieClip(); because it will throw an error again as earlier in Flash, but in Flex in function not? Is Flash changing somehow my loop before compilation? .3. Where in a class in equivalent to timeline in Flash - where in class I would put code which I put normally on timeline (I assume it is not constructor because of what I have written earlier, or maybe it`s a matter of Flash/Flex compiler)?

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  • Practical rules for premature optimization

    - by DougW
    It seems that the phrase "Premature Optimization" is the buzz-word of the day. For some reason, iphone programmers in particular seem to think of avoiding premature optimization as a pro-active goal, rather than the natural result of simply avoiding distraction. The problem is, the term is beginning to be applied more and more to cases that are completely inappropriate. For example, I've seen a growing number of people say not to worry about the complexity of an algorithm, because that's premature optimization (eg http://stackoverflow.com/questions/2190275/help-sorting-an-nsarray-across-two-properties-with-nssortdescriptor/2191720#2191720). Frankly, I think this is just laziness, and appalling to disciplined computer science. But it has occurred to me that maybe considering the complexity and performance of algorithms is going the way of assembly loop unrolling, and other optimization techniques that are now considered unnecessary. What do you think? Are we at the point now where deciding between an O(n^n) and O(n!) complexity algorithm is irrelevant? What about O(n) vs O(n*n)? What do you consider "premature optimization"? What practical rules do you use to consciously or unconsciously avoid it? This is a bit vague, but I'm curious to hear other peoples' opinions on the topic.

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  • Grails or Play! for an ex-RoR developer ?

    - by Kedare
    Hello, I plan to begin learning a Java web framework (I love the Java API), I already used Rails and Django. I want something close to Java, but without all the complexity of J2EE. I've found 2 framework that could be good for me : Grails : Grails looks great, it use Groovy that is better than Java for web application (I think..), but it's slower, that use pure-java components (Hibernate, Strut, Spring), it looks pretty simple to deploy (send .war and it's ok !), the GSP is great ! It's a bit harder to debug (need to restart the server at each modification, and the stacktrace is a mix of Java and Groovy stack that is not always understandable..) Play! : This framework also looks great, it's faster than Grails (It's use directly Java), but I don't really like how it use Java, it modify the source code to transform the properties call as setXXX/getXXX, I'm not kind of that... The framework also have caching function that Grails don't (alreary) has. I don't really like the Template Engine. It's also easer to debug (no need to restart the server, and the stacktrace is clear) What do you recommend for ? I am looking for something easy to learn (I used a lot ruby and java, but a little bit java (But I love the Java API)), that is full featured (That's no a problem with all the Java Library availables, but if it's bundle and integrated I prefer), that scale and that is not too slow (faster than ruby), and if possible I would want something with a decent community to easily find support and answer to my questions ;) PS: No JRuby on Rails Thank you !

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  • How to use generic (NSObject) controller with subviews of a UIViewController?

    - by wanderlust
    I have a UIViewController that is loading several subviews at different times based on user interaction. I originally built all of these subviews in code, with no nib files. Now I am moving to nib files with custom UIView subclasses. Some of these subviews display static data, and I am using loadNibNamed:owner:options: to load them into the view controller. Others contain controls that I need to access. I (sort of) understand the reasons Apple says to use one view controller per screen of content, using generic controller objects (NSObjects) to manage subsections of a screen. So I need a view controller, a generic controller, a view class and a nib. How do I put this all together? My working assumptions and subsequent questions: I will associate the view class with the nib in the 'class identity' drop down in IB. The view controller will coordinate overall screen interactions. When necessary, it will create an instance of the generic controller. Does the generic controller load the nib? How? Do I define the outlets and actions in that view class, or should they be in the generic controller? How do I pass messages between the view controller and the generic controller? If anyone can point me to some sample code using a controller in this way, it will go a long way to helping me understand. None of the books or stackoverflow posts I've read have quite hit the spot yet.

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  • Approach for fixing NoClassDefFoundError?

    - by DJC
    I'm seeing this question is getting asked a lot in many different contexts. Perhaps we can set some strategies for locating and fixing it? I'm noobish myself so all I can contribute are horror stories and questions, sorry... It seems this is thrown when a class is visible at compile time but not at run time... how can this happen? In my case I am developing an app that uses the Google APIs, in Eclipse, for the Android platform. I've configured the Project Properties / Java Build Path / Libraries to include the gdata .jars and all is well. When I execute in the emulator I get a force close and the logcat shows a NoClassDefFoundError on a simple new ContactsService("myApp"); I've also tried a new CalendarService("myApp") with the same results. Is it possible or desirable to statically bind at compile time to avoid the problem? How could dynamic binding of an add-on library work in the mobile environment anyway? Either it has to be bound into my .apk or else I need to "install" it? ... hmmm. Advice much appreciated.

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  • CSS Design question, I've got myself completely turned around.

    - by Matt Dawdy
    Okay, I have a couple of other questions out there, but I think I'd better just ask from the beginning how you CSS experts would do this. Client's page is split into 2 rows -- header has some info, some aligned to left of page, some to right, some in the middle. This is currently done using a table. I'm fine with leaving this alone or changing it. My real question is that I need a page layout to handle the following: 2 columns - column on left is 200px, but can be "close" down to to 10px (not a slider, it's either 200 or 10 px). The column on the right needs to be as big as it needs to be -- which might be larger than the width of the page. When left column is "closed" then the right column slides over of course. Again, this right column might be 300px or it might be 4000 pixels (it's a reporting interface). Now, to add another wrinkle, SOME pages have 3 columns. The first 2 columns are each exactly 200px, and both can be "closed" down to 10 px each. But, the user may not close both columns, maybe just 1. Or none. Or both. The third column needs to act just like I described above, being able to be larger than the page width, and sliding over to take advantage of any of the "closed" left columns. Whew! I'm pretty confused as to how to go about this, as either I get it right but I can't scroll over to the right at all (overflow: hidden) and information is lost, or the right column jumps down below the left 2 columns and just looks plain stupid. My minimum browser requirements are IE8, FF3.5, Chrome and Safari (latest versions of all). Any and all pointers are gladly accepted.

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  • Yet another Haskell vs. Scala question

    - by Travis Brown
    I've been using Haskell for several months, and I love it—it's gradually become my tool of choice for everything from one-off file renaming scripts to larger XML processing programs. I'm definitely still a beginner, but I'm starting to feel comfortable with the language and the basics of the theory behind it. I'm a lowly graduate student in the humanities, so I'm not under a lot of institutional or administrative pressure to use specific tools for my work. It would be convenient for me in many ways, however, to switch to Scala (or Clojure). Most of the NLP and machine learning libraries that I work with on a daily basis (and that I've written in the past) are Java-based, and the primary project I'm working for uses a Java application server. I've been mostly disappointed by my initial interactions with Scala. Many aspects of the syntax (partial application, for example) still feel clunky to me compared to Haskell, and I miss libraries like Parsec and HXT and QuickCheck. I'm familiar with the advantages of the JVM platform, so practical questions like this one don't really help me. What I'm looking for is a motivational argument for moving to Scala. What does it do (that Haskell doesn't) that's really cool? What makes it fun or challenging or life-changing? Why should I get excited about writing it?

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