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  • Aborted core dumped C++

    - by avd
    I have a large C++ function which uses OpenCV library and running on Windows with cygwin g++ compiler. At the end it gives Aborted(core dumped) but the function runs completely before that. I have also tried to put the print statement in the end of the function. That also gets printed. So I think there is no logical bug in code which will generate the fault. Please explain. I am also using assert statements.But the aborted error is not due to assert statement. It does not say that assertion failed. It comes at end only without any message. Also the file is a part of a large project so I cannot post the code also.

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  • C pointer question, dereferencing crash

    - by skynorth
    Why do this work? int *var; while(scanf("%d", &var) && *var != 0) printf("%d \n", var); While this does not? int *var; while(scanf("%d", &var) && var != 0) printf("%d \n", var); Doesn't * (dereference operator) give you the value pointed by the pointer? So why does *var != 0 crash the program, while var != 0 does not?

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  • Get file size of BufferedImage before writing the data

    - by David
    I'm working on a Java program that needs to send an image (preferably in PNG format, though I could perhaps use another format if necessary) over the network. The logical way to do this is, of course, to first send the length of the PNG image data, then the data itself. Problem: I don't see any method in ImageIO or anywhere else that will give me the length of the image data. Does this exist somewhere in the Java 1.6 standard library? I know I could just write it to a ByteArrayOutputStream and get the length of the resulting array, but before resorting that I wanted to make sure I'm not missing something built in. And besides, that makes an extra copy of the image data, which I'd rather not do if it's not necessary.

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  • RegularExpressionValidator always fails, but ValidationExpression works in testing

    - by Jerph
    I found the answer to this, but it's a bit of a gotcha so I wanted to share it here. I have a regular expression that validates passwords. They should be 7 to 60 characters with at least one numeric and one alpha character. Pretty standard. I used positive lookaheads (the (?= operator) to implement it: (?=^.{7,60}$)(?=.*[0-9].*)(?=.*[a-zA-Z].*) I checked this expression in my unit tests using Regex.IsMatch(), and it worked fine. However, when I use it in a RegularExpressionValidator, it always fails. Why?

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  • deleting dynamically allocated object that contains vector in C++ STL

    - by kobac
    I have a class class ChartLine{ protected: vector<Point> line; // points connecting the line CString name; //line name for legend CPen pen; //color, size and style properties of the line }; where Point is a structure struct Point{ CString x; double y; }; In main() I dynamically allocate objects of type ChartLine with new operator. If I use delete afterwards, will default destructor ~ChartLine() properly dealocate (or clear) member ChartLine::line(which is vector btw) or I would have to clear that vector in ~ChartLine() manually? Thanks in advance. Cheers.

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  • How to retrieve all keys (or values) from a std::map?

    - by Owen
    This is one of the possible ways I come out: struct RetrieveKey { template <typename T> typename T::first_type operator()(T keyValuePair) const { return keyValuePair.first; } }; map<int, int> m; vector<int> keys; // Retrieve all keys transform(m.begin(), m.end(), back_inserter(keys), RetrieveKey()); // Dump all keys copy(keys.begin(), keys.end(), ostream_iterator<int>(cout, "\n")); Of course, we can also retrieve all values from the map by defining another functor RetrieveValues. Is there any other way to achieve this easily? (I'm always wondering why std::map does not include a member function for us to do so.)

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  • Any way to make a generic List where I can add a type AND a subtype?

    - by user383178
    I understand why I cannot do the following: private class Parent { }; private class Child extends Parent { }; private class GrandChild extends Child { }; public void wontCompile(List<? extends Parent> genericList, Child itemToAdd) { genericList.add(itemToAdd); } My question is there ANY practical way to have a typesafe List where you can call add(E) where E is known to be only a Parent or a Child? I vaguely remember some use of the "|" operator as used for wildcard bounds, but I cannot find it in the spec... Thanks!

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  • can we write this in C++ switch ?

    - by jellly
    #include <iostream> using namespace std; int main(){ char i; cin >>i; switch (i){ case ('e'||'i'||'o'||'u'||'a'): cout<<"Vowel"; break; case ('+'||'-'||'/'||'*'||'%'): cout<<"Op"; break; } return 0; } if not than how can we use comparison or logical operators in switch ? & why cant we declare and initialize variable in single case without using scope ?

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  • How do I sub sample data by group using ddply?

    - by Maiasaura
    I've got a data frame with far too many rows to be able to do a spatial correlogram. Instead, I want to grab 40 rows for each species and run my correlogram on that subset. I wrote a function to subset a data frame as follows: samp <- function(dataf) { dataf[sample(1:dim(dataf)[1], size=40, replace=FALSE),] } Now I want to apply this function to each species in a larger data frame. When I try something like culled_data = ddply (larger_data, .(species), subset, samp) I get this error: Error in subset.data.frame(piece, ...) : 'subset' must evaluate to logical Anyone got ideas on how to do this?

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  • Friendness and derived class

    - by ereOn
    Hi, Let's say I have the following class hierarchy: class Base { protected: virtual void foo() = 0; friend class Other; }; class Derived : public Base { protected: void foo() { /* Some implementation */ }; }; class Other { public: void bar() { Derived* a = new Derived(); a->foo(); // Compiler error: foo() is protected within this context }; }; I guess I could change it too a->Base::foo() but since foo() is pure virtual in the Base class, the call will result in calling Derived::foo() anyway. However, the compiler seems to refuse a->foo(). I guess it is logical, but I can't really understand why. Am I missing something ? Can't (shouldn't) it handle this special case ? Thank you.

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  • Why the streams in C++?

    - by oh boy
    As you all know there are libraries using streams such as iostream and fstream. My question is: Why streams? Why didn't they stick with functions similar to print, fgets and so on (for example)? They require their own operators << and >> but all they do could be implemented in simple functions like above, also the function printf("Hello World!"); is a lot more readable and logical to me than cout << "Hello World"; I also think that all of those string abstractions in C++ all compile down to (less efficient) standard function calls in binary.

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  • How do I put logic in a View a scope or method in a Model?

    - by Angela
    I have the following in the view: <% unless contact_email.statuses.empty?%> (<%= contact_email.statuses.find(:last).status%>) <% end %> contact_email is an instance of a specific model. Could I do something like this? class ContactEmail < ActiveRecord::Base attr_accessible :contact_id, :email_id, :status, :subject, :body, :date_created, :date_sent def status unless contact_email.statuses.empty? contact_email.statuses.find(:last).status end end end is there a better way to do this? is there a way to use the || operator for a default if empty? Basically, I would like to be able to do the following in the View: <%= contact_email.status = IF there is a value, then display it, if not, show nothing.

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  • Joining two select queries and ordering results

    - by user1
    Basically I'm just unsure as to why this query is failing to execute: (SELECT replies.reply_post, replies.reply_content, replies.reply_date AS d, members.username FROM (replies) AS a INNER JOIN members ON replies.reply_by = members.id) UNION (SELECT posts.post_id, posts.post_title, posts.post_date AS d, members.username FROM (posts) as b WHERE posts.post_set = 0 INNER JOIN members ON posts.post_by = members.id) ORDER BY d DESC LIMIT 5 I'm getting this error: #1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'a INNER JOIN members ON replies.re' at line 2 All I'm trying to do is select the 5 most recent rows (dates) from these two tables. I've tried Join, union etc and I've seen numerous queries where people have put another query after the FROM statement and that just makes no logical sense to me as to how that works? Am I safe to say that you can join the same table from two different but joined queries? Or am I taking completely the wrong approach, because frankly I can't seem see how this query is failing despite reading the error message. (The two queries on there own work fine)

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  • Why does Java ArrayList use per-element casting instead of per-array casting?

    - by user1111929
    What happens inside Java's ArrayList<T> (and probably many other classes) is that there is an internal Object[] array = new Object[n];, to which T Objects are written. Whenever an element is read from it, a cast return (T) array[i]; is done. So, a cast on every single read. I wonder why this is done. To me, it seems like they're just doing unnecessary casts. Wouldn't it be more logical and also slightly faster to just create a T[] array = (T[]) new Object[n]; and then just return array[i]; without cast? This is only one cast per array creation, which is usually far less than the number of reads. Why is their method to be preferred? I fail to see why my idea isn't strictly better?

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  • Retrieving a single Guid in CRM 4.0

    - by user1746560
    I'm new to CRM (version 4.0) and i'm trying to return a 'yearid' guide based on a given year (which is also stored in the entity).So far i've got: public static Guid GetYearID(string yearName) { ICrmService service = CrmServiceFactory.GetCrmService(); // Create the query object. QueryExpression query = new QueryExpression("year"); ColumnSet columns = new ColumnSet(); columns.AddColumn("yearid"); query.ColumnSet = columns; FilterExpression filter = new FilterExpression(); filter.FilterOperator = LogicalOperator.And; filter.AddCondition(new ConditionExpression { AttributeName = "yearName", Operator = ConditionOperator.Equal, Values = new object[] { yearName} }); query.Criteria = filter; } But my questions are: A) What code do in addition to this to actually store the Guid? B) Is using a QueryExpression the most efficient way to do this?

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  • Why SQL functions are faster than UDF

    - by Zerotoinfinite
    Though it's a quite subjective question but I feel it necessary to share on this forum. I have personally experienced that when I create a UDF (even if that is not complex) and use it into my SQL it drastically decrease the performance. But when I use SQL inbuild function they happen to work pretty faster. Conversion , logical & string functions are clear example of that. So, my question is "Why SQL in build functions are faster than UDF"? and it would be an advantage if someone can guide me how can I judge/manipulate function cost either mathematically or logically.

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  • How should I get Xcode to link an iOS project that uses a C++ static library

    - by user1681572
    Using Xcode, I've written a Cocoa Touch static library, mainly in C++. It exposes a C interface for the benefit of Objective-C client code. I have a client iOS app that uses it, and everything works and runs as expected, except that I found I needed to include a minimal .cpp file in the client project to get the link to succeed. Otherwise I get C++-related unresolved symbols, e.g. operator new(unsigned long). The above hack is easy and effective, and so I guess I'm not breaking any laws, but is there a proper way to eliminate my linker errors?

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  • calling a java class in a servlet

    - by kawtousse
    hi, in my servlet i called an instance of a class.java( a class that construct an html table) in order to create this table in my jsp. the servlet is like the following: String report=request.getParameter("selrep"); String datev=request.getParameter("datepicker"); String op=request.getParameter("operator"); String batch =request.getParameter("selbatch"); System.out.println("report kind was:"+report); System.out.println("date was:"+datev); System.out.println("operator:"+op); System.out.println("batch:"+batch); if(report.equalsIgnoreCase("Report Denied")) { DeniedReportDisplay rd = new DeniedReportDisplay(); rd.ConstruireReport(); } else if(report.equalsIgnoreCase("Report Locked")) { LockedReportDisplay rl = new LockedReportDisplay(); rl.ConstruireReport(); } request.getRequestDispatcher("EspaceValidation.jsp").forward(request, response); in my jsp i can not display this table even empty or full. note: exemple a class that construct denied Report has this structure: /*constructeur*/ public DeniedReportDisplay() {} /*Methodes*/ @SuppressWarnings("unchecked") public StringBuffer ConstruireReport() { StringBuffer retour=new StringBuffer(); int i = 0; retour.append("<table border = 1 width=900 id=sheet align=left>"); retour.append("<tr bgcolor=#0099FF>" ); retour.append("<label> Denied Report</label>"); retour.append("</tr>"); retour.append("<tr>"); String[] nomCols ={"Nom","Prenom","trackingDate","activity","projectcode","WAName","taskCode","timeSpent","PercentTaskComplete","Comment"}; //String HQL_QUERY = null; for(i=0;i< nomCols.length;i++) { retour.append(("<td bgcolor=#0066CC>")+ nomCols[i] + "</td>"); } retour.append("</tr>"); retour.append("<tr>"); try { s= HibernateUtil.currentSession(); tx=s.beginTransaction(); Query query = s.createQuery("select opcemployees.Nom,opcemployees.Prenom,dailytimesheet.TrackingDate,dailytimesheet.Activity," + "dailytimesheet.ProjectCode,dailytimesheet.WAName,dailytimesheet.TaskCode," + "dailytimesheet.TimeSpent,dailytimesheet.PercentTaskComplete from Opcemployees opcemployees,Dailytimesheet dailytimesheet " + "where opcemployees.Matricule=dailytimesheet.Matricule and dailytimesheet.Etat=3 " + "group by opcemployees.Nom,opcemployees.Prenom" ); for(Iterator it=query.iterate();it.hasNext();) { if(it.hasNext()){ Object[] row = (Object[]) it.next(); retour.append("<td>" +row [0]+ "</td>");//Nom retour.append("<td>" + row [1] + "</td>");//Prenom retour.append("<td>" + row [2] + "</td>");//trackingdate retour.append("<td>" + row [3]+ "</td>");//activity retour.append("<td>" + row [4] +"</td>");//projectcode retour.append("<td>" + row [5]+ "</td>");//waname retour.append("<td>" + row [6] + "</td>");//taskcode retour.append("<td>" + row [7] + "</td>");//timespent retour.append("<td>" + row [8] + "</td>");//perecnttaskcomplete retour.append("<td><input type=text /></td>");//case de commentaire } retour.append("</tr>"); } //terminer la table. retour.append ("</table>"); tx.commit(); } catch (HibernateException e) { retour.append ("</table><H1>ERREUR:</H1>" +e.getMessage()); e.printStackTrace(); } return retour; } thanks for help.

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  • ActionScript: Using 'in' on protected/private variables?

    - by David Wolever
    Is there any way to mimic the in operator, but testing for the existence of protected or private fields? For example, this: <mx:Script><![CDATA[ public var pub:Boolean = true; protected var prot:Boolean = true; private var priv:Boolean = true; ]]></mx:Script> <mx:creationComplete><![CDATA[ for each (var prop in ["pub", "prot", "priv", "bad"]) trace(prop + ":", prop in this); ]]></mx:creationComplete> Will trace: pub: true prot: false priv: false bad: false When I want to see: pub: true prot: true priv: true bad: false

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  • Using Linq to filter parents by their children

    - by Nick L
    Having some problems with my Silverlight app (with RIA services) filtering my results. The idea is on the client I set up the EntityQuery and its filters and call load. However this isn't working for me. Heres my code. public void FireQuery(string filterValue) { EntityQuery<Parent> query = m_ParentDomainContext.GetParentQuery(); query = query.Where(p => p.Children.Any(c => c.Name.Contains(filterValue))); m_ParentDomainContext.Load(query, Query_Completed, null); } Compiles just fine, however, runtime I get "Query operator 'Any' is not supported." Exception. Does anyone know of a good way to filter like this? Again, I'm looking for a way to set this up on the client.

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  • What is the right way to implement communication between java objects?

    - by imoschak
    I'm working on an academic project which simulates a rather large queuing procedure in java. The core of the simulator rests within one package where there exist 8 classes, each one implementing a single concept. Every class in the project follows SRP. These classes encapsulate the behavior of the simulator and inter-connect every other class in the project. The problem that has arisen is that most of these 8 classes are, as is logical i think, tightly coupled and each one has to have working knowledge of every other class in this package in order to be able to call methods from it when needed. The application needs only one instance of each class so it might be better to create static fields for each class in a new class and use that to make calls -instead of preserving a reference in each class for every other class in the package (which I'm certain that is incorrect)-, but is this considered a correct design solution? or is there a design pattern maybe that better suits my needs?

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  • C++ How do you set an array of pointers to null in an initialiser list like way?

    - by boredjoe
    I am aware you cannot use an initialiser list for an array. However I have heard of ways that you can set an array of pointers to NULL in a way that is similar to an initialiser list. I am not certain how this is done. I have heard that a pointer is set to NULL by default, though I do not know if this is guaranteed/ in the C++ standard. I am also not sure if initialising through the new operator compared to normal allocation can make a difference too.

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  • C++ Iterators and inheritance

    - by jomnis
    Have a quick question about what would be the best way to implement iterators in the following: Say I have a templated base class 'List' and two subclasses "ListImpl1" and "ListImpl2". The basic requirement of the base class is to be iterable i.e. I can do: for(List<T>::iterator it = list->begin(); it != list->end(); it++){ ... } I also want to allow iterator addition e.g.: for(List<T>::iterator it = list->begin()+5; it != list->end(); it++){ ... } So the problem is that the implementation of the iterator for ListImpl1 will be different to that for ListImpl2. I got around this by using a wrapper ListIterator containing a pointer to a ListIteratorImpl with subclasses ListIteratorImpl2 and ListIteratorImpl2, but it's all getting pretty messy, especially when you need to implement operator+ in the ListIterator. Any thoughts on a better design to get around these issues?

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  • What does it mean when a Perl method returns a "hashref"?

    - by Uri
    I'm trying to decrypt a Perl code which I'm not familiar with, somehow related to HashRef. I'm using Amazon::S3, but my question is a general Perl question. See the code below: use Amazon::S3; my $s3 = Amazon::S3->new( ... ); my $response = $s3->buckets; Documentation (here) sais, about s3-buckets: Returns undef on error, else HASHREF of results The following line is working for me, but I don't understand why: for $b in ( @ { $response->{buckets} } ) { print "bucket: " . $b->bucket . "\n"; } I'm Puzzled by each operator on the first line. What type exactly are $response, $respone->{bucket}. Looks like the expression within the for is an array, but I don't understand this syntax: @{ ... }?

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  • InApp subscriptions - trasferability

    - by meap
    Apple has rejected one of our apps, where the user can purchase content through subscriptions (InApp product type is subscription). The problem is that we need to, also because of Apple requiring it, these subscriptions to be transferable between devices. The logical and also the most secure solution would be to link it to a user account, that the user will have to create. But this was the reason why apple rejected this app. They have told us that for purchasing of subscriptions a registration can not be required, can be only optional. So the question is how to solve this if there is no other nice solution that would make sense, be secure and still comfortable for the user?

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