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  • How do I use a shared library (in this case JsonCpp) in my C++ program on Linux?

    - by Not Joe Bloggs
    I'm a new-ish C++ programmer, and I'm doing my first program on my own using C++. I decided I would like to use JSON to store some of the data I'm going to be using, and I've found a library to handle JSON, JsonCpp. I've installed the library using my Linux system's package manager, and in my C++ code, I've used in my source code file #include <json> and compiled it using g++ and it's -ljson and -L/usr/lib options (libjson.so is located in /usr/lib). However, the first usage of Json::Value, an object provided by the library, gives a compilation error of "Json has not declared". I'm sure my mistake is something simple, so could someone explain what I'm doing wrong? None of the books I had mention how to use shared libraries, so I've had to google to find this much.

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  • how to make a name from random numbers?

    - by blood
    my program makes a random name that could have a-z this code makes a 16 char name but :( my code wont make the name and idk why :( can anyone show me what's wrong with this? char name[16]; void make_random_name() { byte loop = -1; for(;;) { loop++; srand((unsigned)time(0)); int random_integer; random_integer = (rand()%10)+1; switch(random_integer) { case '1': name[loop] = 'A'; break; case '2': name[loop] = 'B'; break; case '3': name[loop] = 'C'; break; case '4': name[loop] = 'D'; break; case '5': name[loop] = 'E'; break; case '6': name[loop] = 'F'; break; case '7': name[loop] = 'G'; break; case '8': name[loop] = 'Z'; break; case '9': name[loop] = 'H'; break; } cout << name << "\n"; if(loop > 15) { break; } } }

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  • What is the full "for" loop syntax in C (and others in case they are compatible) ?

    - by fmsf
    I have seen some very weird for loops when reading other people's code. I have been trying to search for a full syntax explanation for the for loop in C but it is very hard because the word "for" appears in unrelated sentences making the search almost impossible to Google effectively. This question came to my mind after reading this thread which made me curious again. The for here: for(p=0;p+=(a&1)*b,a!=1;a>>=1,b<<=1); In the middle condition there is a comma separating the two pieces of code, what does this comma do? The comma on the right side I understand as it makes both a>>=1 and b<<=1. But within a loop exit condition, what happens? Does it exit when p==0, when a==1 or when both happen? It would be great if anyone could help me understand this and maybe point me in the direction of a full for loop syntax description.

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  • Write to static field - is FindBugs wrong in this case?

    - by htorque
    I have a Java class like this: public class Foo { public static int counter = 0; public void bar(int counter) { Foo.counter = counter; } } FindBugs warns me about writing to the static field counter via the instance method bar. However, if I change the code to: public class Foo { public static int counter = 0; public static void setCounter(int counter) { Foo.counter = counter; } public void bar(int counter) { setCounter(counter); } } Then FindBugs won't complain. Isn't that wrong? I'm still writing to a static field from an instance method, just via a static method - no?

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  • Getting bizarre "expected primary-expression" error.

    - by Fecal Brunch
    Hi, I'm getting a really strange error when making a method call: /* input.cpp */ #include <ncurses/ncurses.h> #include "input.h" #include "command.h" Input::Input () { raw (); noecho (); } Command Input::next () { char input = getch (); Command nextCommand; switch (input) { case 'h': nextCommand.setAction (ACTION_MOVELEFT); break; case 'j': nextCommand.setAction (ACTION_MOVEDOWN); break; case 'k': nextCommand.setAction (ACTION_MOVEUP); break; case 'l': nextCommand.setAction (ACTION_MOVERIGHT); break; case 'y': nextCommand.setAction (ACTION_MOVEUPLEFT); break; case 'u': nextCommand.setAction (ACTION_MOVEUPRIGHT); break; case 'n': nextCommand.setAction (ACTION_MOVEDOWNLEFT); break; case 'm': nextCommand.setAction (ACTION_MOVEDOWNRIGHT); break; case '.': nextCommand.setAction (ACTION_WAIT); break; } return nextCommand; } and the error: Administrator@RHYS ~/code/rogue2 $ make g++ -c -Wall -pedantic -g3 -O0 input.cpp input.cpp: In member function `Command Input::next()': input.cpp:21: error: expected primary-expression before '=' token input.cpp:24: error: expected primary-expression before '=' token input.cpp:27: error: expected primary-expression before '=' token input.cpp:30: error: expected primary-expression before '=' token input.cpp:33: error: expected primary-expression before '=' token input.cpp:36: error: expected primary-expression before '=' token input.cpp:39: error: expected primary-expression before '=' token input.cpp:42: error: expected primary-expression before '=' token input.cpp:45: error: expected primary-expression before '=' token make: *** [input.o] Error 1 Sorry about the lack of linenumbers, the errors occur on the lines "nextCommand.setAction(...)", which is totally bizarre considering that they don't contain a '='. Any ideas? Thanks, Rhys

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  • javascript keypress function: case-insensitive a-z, numbers and a few special chars?

    - by user239831
    hey guys, $('.s').keyup(function(e) { if (!/[A-Za-z0-9]/.test(String.fromCharCode(e.which))) { return false; } I wonder what is the best regex solution for my application. I have an ajax-based search that should just trigger the search when actual characters are pressed like a-Z (upper and lowercase), numbers and maybe a questionmark, a dash(hyphen), and an exclamation mark. Also the spacebar should be enabled. Otherwise the ajax search would be triggered as well if the shift-, option, or control-key, is pressed. What's the easiest regex pattern to understand here? thank you for your help

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  • Why doesn't Default route work using Html.ActionLink in this case?

    - by StuperUser
    I have a rather perculiar issue with routing. Coming back to routing after not having to worry about configuration for it for a year, I am using the default route and ignore route for resources: routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); routes.MapRoute( "Default", // Route name "{controller}/{action}/{id}", // URL with parameters new { controller = "Home", action = "Index", id = UrlParameter.Optional }); I have a RulesController with an action for Index and Lorem and a Index.aspx, Lorem.aspx in Views Rules directory. I have an ActionLink aimed at Rules/Index on the maseter page: <li><div><%: Html.ActionLink("linkText", "Index", "Rules")%></div></li> The link is being rendered as http://localhost:12345/Rules/ and am getting a 404. When I type Index into the URL the application routes it to the action. When I change the default route action from "Index" to "Lorem", the action link is being rendered as http://localhost:12345/Rules/Index adding the Index as it's no longer on the default route and the application routes to the Index action correctly. I have used Phil Haack's Routing Debugger, but entering the url http://localhost:12345/Rules/ is causing a 404 using that too. I think I've covered all of the rookie mistakes, relevant SO questions and basic RTFMs. I'm assuming that "Rules" isn't any sort of reserved word in routing. Other than updating the Routes and debuugging them, what can I look at?

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  • Scala newbie vproducer/consumer attempt running out of memory

    - by Nick
    I am trying to create a producer/consumer type Scala app. The LoopControl just sends a message to the MessageReceiver continually. The MessageReceiver then delegates work to the MessageCreatorActor (whose work is to check a map for an object, and if not found create one and start it up). Each MessageActor created by this MessageCreatorActor is associated with an Id. Eventually this is where I want to do business logic. But I run out of memory after 15 minutes. Its finding the cached actors,but quickly runs out of memory. Any help is appreciated. Or any one has any good code on producers consumers doing real stuff (not just adding numbers), please post. import scala.actors.Actor import java.util.HashMap import scala.actors.Actor._ case object LoopControl case object MessageReceiver case object MessageActor case object MessageActorCreator class MessageReceiver(msg: String) extends Actor { var messageActorMap = new HashMap[String, MessageActor] val messageCreatorActor = new MessageActorCreator(null, null) def act() { messageCreatorActor.start loop { react { case MessageActor(messageId) => if (msg.length() > 0) { var messageActor = messageActorMap.get(messageId); if(messageActor == null) { messageCreatorActor ! MessageActorCreator(messageId, messageActorMap) }else { messageActor ! MessageActor } } } } } } case class MessageActorCreator(msg:String, messageActorMap: HashMap[String, MessageActor]) extends Actor { def act() { loop { react { case MessageActorCreator(messageId, messageActorMap) => if(messageId != null ) { var messageActor = new MessageActor(messageId); messageActorMap.put(messageId, messageActor) println(messageActorMap) messageActor.start messageActor ! MessageActor } } } } } class LoopControl(messageReceiver:MessageReceiver) extends Actor { var count : Int = 0; def act() { while (true) { messageReceiver ! MessageActor ("00-122-0X95-FEC0" + count) //Thread.sleep(100) count = count +1; if(count > 5) { count = 0; } } } } case class MessageActor(msg: String) extends Actor { def act() { loop { react { case MessageActor => println() println("MessageActor: Got something-> " + msg) } } } } object messages extends Application { val messageReceiver = new MessageReceiver("bootstrap") val loopControl = new LoopControl(messageReceiver) messageReceiver.start loopControl.start }

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  • How do I create a regular expression to match a word misspelling the original case sensitivity?

    - by Patrick Allaert
    I want to discover wrong spelling of "FooBar" in sentence: "This is a 'FooBar' example where I should match different spelling of fooBar such as: foobar, FOOBAR or even fOoBaR but not foobarS!" In this sentence, I would like to match words (in order): fooBar, foobar, FOOBAR, fOoBaR and not: FooBar (correct spelling), foobarS (not the same word) Is there an existing solution using Perl Regular Expression? This is intended to be used with grep -P Thanks

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  • Is there any algorithm for determining 3d position in such case? (images below)

    - by Ole Jak
    So first of all I have such image (and ofcourse I have all points coordinates in 2d so I can regenerate lines and check where they cross each other) But hey, I have another Image of same lines (I know thay are same) and new coords of my points like on this image So... now Having points (coords) on first image, How can I determin plane rotation and Z depth on second image (asuming first one's center was in point (0,0,0) with no rotation)?

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  • R: How to pass a list of selection expressions (strings in this case) to the subset function?

    - by John
    Here is some example data: data = data.frame(series = c("1a", "1b", "1e"), reading = c(0.1, 0.4, 0.6)) > data series reading 1 1a 0.1 2 1b 0.4 3 1e 0.6 Which I can pull out selective single rows using subset: > subset (data, series == "1a") series reading 1 1a 0.1 And pull out multiple rows using a logical OR > subset (data, series == "1a" | series == "1e") series reading 1 1a 0.1 3 1e 0.6 But if I have a long list of series expressions, this gets really annoying to input, so I'd prefer to define them in a better way, something like this: series_you_want = c("1a", "1e") (although even this sucks a little) and be able to do something like this, subset (data, series == series_you_want) The above obviously fails, I'm just not sure what the best way to do this is?

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  • Is it undefined behavior in the case of the private functions call in the initializer list?

    - by Alexey Malistov
    Consider the following code: struct Calc { Calc(const Arg1 & arg1, const Arg2 & arg2, /* */ const ArgN & argn) : arg1(arg1), arg2(arg2), /* */ argn(argn), coef1(get_coef1()), coef2(get_coef2()) { } int Calc1(); int Calc2(); int Calc3(); private: const Arg1 & arg1; const Arg2 & arg2; // ... const ArgN & argn; const int coef1; // I want to use const because const int coef2; // no modification is needed. int get_coef1() const { // calc coef1 using arg1, arg2, ..., argn; // undefined behavior? } int get_coef2() const { // calc coef2 using arg1, arg2, ..., argn and coef1; // undefined behavior? } }; struct Calc is not completely defined when I call get_coef1 and get_coef2 Is this code valid? Can I get UB?

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  • What is the benefit of using int instead of bigint in this case?

    - by Yeti
    (MYSQL n00b) I have 3 tables: id = int(10), photo_id = bigint(20) PHOTO records limited to 3 million PHOTO: +-------+-----------------+ | id | photo_num | +-------+-----------------+ | 1 | 123456789123 | | 2 | 987654321987 | | 3 | 5432167894321 | +-------+-----------------+ COLOR: +-------+-----------------+---------+ | id | photo_num | color | +-------+-----------------+---------+ | 1 | 123456789123 | red | | 2 | 987654321987 | blue | | 3 | 5432167894321 | green | +-------+-----------------+---------+ SIZE: +-------+-----------------+---------+ | id | photo_num | size | +-------+-----------------+---------+ | 1 | 123456789123 | large | | 2 | 987654321987 | small | | 3 | 5432167894321 | medium | +-------+-----------------+---------+ Both COLOR and SIZE tables will have several million records. Q1: Is it better to change photo_num on COLOR and SIZE to int(10) and point it to PHOTO's id? Right now I use these: (PHOTO is no where in the picture) SELECT * from COLOR WHERE photo_num='xxx'; SELECT * from SIZE WHERE photo_num='xxx'; Q2: How will the SELECT query look if PHOTO id was used in COLOR, SIZE?

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  • How to create a platform ontop of CSLA? <-- if in case it make sense

    - by Peejay
    Hi all! here is the senario, i'm developing an application using csla 3.8 / c#.net, the application will have different modules. its like an ERP, it will have accounting, daily time record, recruitment etc as modules. Now the requirement is to check for common entities per module and build a "platform" (<- the boss calls it that way) from it. for example, DTR will have an entity "employee", Recruitment will have "Applicant" so one common entity that you can derive from both that can be put in the platform is "Person". "Person" will contain typical info like name, address, contact info etc. I know it sounds like OOP 101. the thing is, i dont know how i am to go about it. how i wish it was just a simple inheritance but the requirement is like to create an API of some sort to be used by the modules using CSLA. in csla you create smart objects right, inheriting from the base classes of csla like businessListbase, readonlylistbase etc. right? what if for example i created a businessbase Applicant class, it will have properties like salary demand, availability date etc. now for the personal info i will need the "Person" from the "platform" and implement it to the applicant class. so in summary i have several questions: how to create such platform? if such platform is possible, how will it be implemented on each module's entities? (im already inheriting from base clases of csla) if incase 1 and 2 are possible, does it have advantages on development and maintenace of the app? the reason why i'm asking #3 is because the way i see it, even if i am able to create a platform for that, i will be needing to define properties of the platform entity on my module entities so to have validation and all. im sorry if i'm typing nonesense i'm really confused. hope someone could enlighten me. thank you all!

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  • Spring 3 MVC - Does Anything Just Work? Very Simple Use Case Not Working

    - by jboyd
    index.jsp ... <h1> ${myobject} </h1> ... HomeController.java @RequestMapping(value = "/index") public ModelAndView indexPath() { System.out.println("going home"); return new ModelAndView("index", "myobject", "isastring"); } Output: going home The <h1> on index doesn't show anything, how is this even possible? I absolutely cannot get my index.jsp to show this bean, I've tried using a usebean, I've tried storing it on the session, and now I'm directly placing it in the model. Nothing works. Spring 3 has been like every other spring release, intensely frustrating.

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  • What is Perl doing with this argument to push in this case?

    - by Morinar
    I just saw some code in our code base (and it's OLD code, as in Perl 3 or Perl 4 days) that looks like this (I'm simplifying greatly): my @array; push( array, $some_scalar ); Notice that the array in the push() doesn't have an @. I would assume that the code behind push knows that the first argument is supposed to be array so grabs the array from the array typeglob. Is that more or less it? If Perl is able to do that without problem, why would you need to include the @ at all?

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  • What is the best way to setup my tables and relationships for this use case?

    - by Dustin Brewer
    1)A user can have many causes and a cause can belong to many users. 2)A user can have many campaigns and campaigns can belong to many users. Campaigns belong to one cause. I want to be able to assign causes or campaigns to a given user, individually. So a user can be assigned a specific campaign. OR a user could be assigned a cause and all of the campaigns of that cause should then be associated with a user. Is that possible? And could I set it up so that the relationships could be simplified like so: User.causes = all causes that belong to a user User.campaigns = all campaigns that belong to user whether through a cause association or campaign association

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  • switch statement in for loop and if statement not completing

    - by user2373912
    I'm trying to find out how many of each character are in a string. I've searched around for a while and can't seem to figure out why my switch statement is stopping after the first case. function charFreq(string){ var splitUp = string.split(""); console.log(splitUp); var a; var b; var c; var v; for (var i = 0; i<splitUp.length; i++){ if (i<1){ switch (splitUp[i]){ case "a": a = 1; break; case "b": b = 1; break; case "c": c = 1; break; case "v": v = 1; break; } } else { switch (splitUp[i]){ case "a": a += 1; break; case "b": b += 1; break; case "c": c += 1; break; case "v": v += 1; break; } } } console.log("There are " + a + " A's, " + b + " B's, " + c + " C's, and " + v + " V's.") } charFreq("aaabccbbavabac"); What am I doing wrong that would make the console read: There are 6 A's, NaN B's, NaN C's, and NaN V's.

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  • How do I correct feature envy in this case?

    - by RMorrisey
    I have some code that looks like: class Parent { private Intermediate intermediateContainer; public Intermediate getIntermediate(); } class Intermediate { private Child child; public Child getChild() {...} public void intermediateOp(); } class Child { public void something(); public void somethingElse(); } class Client { private Parent parent; public void something() { parent.getIntermediate().getChild().something(); } public void somethingElse() { parent.getIntermediate().getChild().somethingElse(); } public void intermediate() { parent.getIntermediate().intermediateOp(); } } I understand that is an example of the "feature envy" code smell. The question is, what's the best way to fix it? My first instinct is to put the three methods on parent: parent.something(); parent.somethingElse(); parent.intermediateOp(); ...but I feel like this duplicates code, and clutters the API of the Parent class (which is already rather busy). Do I want to store the result of getIntermediate(), and/or getChild(), and keep my own references to these objects?

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