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  • Determine an object's class returned by a factory method (Error: function does not take 1 arguments

    - by tzippy
    I have a factorymethod that either returns an object of baseclass or one that is of derivedclass (a derived class of baseclass). The derived class has a method virtual void foo(int x) that takes one argument. baseclass however has virtual void foo() without an argument. In my code, a factory method returns a pointer of type bar that definetly points to an object of class derivedclass. However since this is only known at runtime I get a compiler error saying that foo() does not take an argument. Can I cast this pointer to a pointer of type derivedclass? std::auto_ptr<baseclass> bar = classfactory::CreateBar(); //returns object of class derivedclass bar->foo(5); class baseclass { public: virtual void foo(); } class derivedclass : public baseclass { public: virtual void foo(int x); }

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  • Perl - Reading .txt files line-by-line and using compare function (printing non-matches only once)

    - by Kurt W
    I am really struggling and have spent about two full days on this banging my head against receiving the same result every time I run this perl script. I have a Perl script that connects to a vendor tool and stores data for ~26 different elements within @data. There is a foreach loop for @data that breaks the 26 elements into $e-{'element1'), $e-{'element2'), $e-{'element3'), $e-{'element4'), etc. etc. etc. I am also reading from the .txt files within a directory (line-by-line) and comparing the server names that exist within the text files with what exists in $e-{'element4'}. The Problem: Matches are working perfectly and only printing one line for each of the 26 elements when there is a match, however non-matches are producing one line for every entry within the .txt files (37 in all). So if there are 100 entries (each entry having 26 elements) stored within @data, then there are 100 x 37 entries being printed. So for every non-match in the: if ($e-{'element4'} eq '6' && $_ =~ /$e-{element7}/i) statement below, I am receiving a print out saying that there is not a match. 37 entries for the same identical 26 elements (because there are 37 total entries in all of the .txt files). The Goal: I need to print out only 1 line for each unique entry (a unique entry being $e-{element1} thru $e-{element26}). It is already printing one 1 line for matches, but it is printing out 37 entries when there is not a match. I need to treat matches and non-matches differently. Code: foreach my $e (@data) { # Open the .txt files stored within $basePath and use for comparison: opendir(DIRC, $basePath . "/") || die ("cannot open directory"); my @files=(readdir(DIRC)); my @MPG_assets = grep(/(.*?).txt/, @files); # Loop through each system name found and compare it with the data in SC for a match: foreach(@MPG_assets) { $filename = $_; open (MPGFILES, $basePath . "/" . $filename) || die "canot open the file"; while(<MPGFILES>) { if ($e->{'element4'} eq '6' && $_ =~ /$e->{'element7'}/i) { ## THIS SECTION WORKS PERFECTLY AND ONLY PRINTS MATCHES WHERE $_ ## (which contains the servernames (1 per line) in the .txt files) ## EQUALS $e->{'element7'}. print $e->{'element1'} . "\n"; print $e->{'element2'} . "\n"; print $e->{'element3'} . "\n"; print $e->{'element4'} . "\n"; print $e->{'element5'} . "\n"; # ... print $e->{'element26'} . "\n"; } else { ## **THIS SECTION DOES NOT WORK**. FOR EVERY NON-MATCH, THERE IS A ## LINE PRINTED WITH 26 IDENTICAL ELEMENTS BECAUSE ITS LOOPING THRU ## THE 37 LINES IN THE *.TXT FILES. print $e->{'element1'} . "\n"; print $e->{'element2'} . "\n"; print $e->{'element3'} . "\n"; print $e->{'element4'} . "\n"; print $e->{'element5'} . "\n"; # ... print $e->{'element26'} . "\n"; } # End of 'if ($e->{'element4'} eq..' statement } # End of while loop } # End of 'foreach(@MPG_assets)' } # End of 'foreach my $e (@data)' I think I need something to identical unique elements and define what fields make up a unique element but honestly I have tried everything I know. If you would be so kind to provide actual code fixes, that would be wonderful because I am headed to production with this script quite soon. Also. I am looking for code (ideally) that is very human-readable because I will need to document it so others can understand. Please let me know if you need additional information.

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  • Expected symbol problems with this function declaration

    - by Derek
    I am just getting back into the C programming realm and I am having an issue that I think is linker related. I am using cmake for the first time as well, so that could be adding to my frustration. I have included a third party header file that contains a typedef that my code is trying to use, and it has this line: typedef struct a a_t so my code has a_t *var; //later..... var->member;// this line throws the error which throws the error: dereferencing pointer to incomplete type So am I just missing another include file, or is this a linker issue? I am building this code in QtCreator and using cmake. I can dive on a_t to see that typedef declaration in the included header, but I can't seem to dive on "struct a" itself to see where it's coming from. Thanks

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  • Traverse a XML using Recursive function

    - by Kaja
    How can I traverse (read all the nodes in order) a XML document using recursive functions in c#? What I want is to read all the nodes in xml (which has attributes) and print them in the same structure as xml (but without Node Localname) Thanks

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  • creating button and calling function on its onclick event using javascript

    - by Deven
    hello friends sorry for previous question actuly my question is i am having one button called btn[0] which is allready on browser when it is loaded when i click on btn[0] it will create another button element called btn[1] now btn[0]'s click event is disabled and when i click on btn[1] it will also generate another button which called btn[2] when i click on btn[2] it will generate another btn called btn[3] and so on

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  • C++ function object terminology functor, deltor, comparitor, etc..

    - by Robert S. Barnes
    Is there a commonly accepted terminology for various types for common functors? For instance I found myself naturally using comparitor for comparison functors like this: struct ciLessLibC : public std::binary_function<std::string, std::string, bool> { bool operator()(const std::string &lhs, const std::string &rhs) const { return strcasecmp(lhs.c_str(), rhs.c_str()) < 0 ? 1 : 0; } }; Or using the term deltor for something like this: struct DeleteAddrInfo { void operator()(const addr_map_t::value_type &pr) const { freeaddrinfo(pr.second); } }; If using these kinds of shorthand terms is common, it there some dictionary of them all someplace?

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  • how to use append function in file

    - by sadia
    I want to write in a file but in a way that it should not delete existing data in that file rather it should append that file. Can anybody please help by giving any example related to appending a file? Thank you

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  • Generic object load function for scala

    - by Isaac Oates
    I'm starting on a Scala application which uses Hibernate (JPA) on the back end. In order to load an object, I use this line of code: val addr = s.load(classOf[Address], addr_id).asInstanceOf[Address]; Needless to say, that's a little painful. I wrote a helper class which looks like this: import org.hibernate.Session class DataLoader(s: Session) { def loadAddress(id: Long): Address = { return s.load(classOf[Address], id).asInstanceOf[Address]; } ... } So, now I can do this: val dl = new DataLoader(s) val addr = dl loadAddress(addr_id) Here's the question: How do I write a generic parametrized method which can load any object using this same pattern? i.e val addr = dl load[Address](addr_id) (or something along those lines.) I'm new to Scala so please forgive anything here that's especially hideous.

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  • How to adjust SQL LIKE function?

    - by slave016
    I want to make this kind of query: create procedure something @name varchar(13) as begin select * from WORKER where NAME LIKE "%@name%" end For input @name=ho, I want output every row that contains NAME wich sounds "ho", for example HOuse, soHO, broHOw...

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  • Function argument treated as undeclared

    - by Mikulas Dite
    I've prepared this simple example which is not working for me #include <stdio.h> #include <stdlib.h> FILE *fp; char filename[] = "damy.txt"; void echo (char[] text) { fp = fopen(filename, "a"); fwrite(text, 1, strlen(text), fp); fclose(fp); printf(text); } int main () { echo("foo bar"); return 0; } It's supposed to write both to command window and to file. However, this gives compilation error - the text used in echo() is not declared. Does c need another declaration of the variable?

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  • Creating a sort function for a generic list

    - by Andrey
    I have a method for sorting generic lists by the object fields: public static IQueryable<T> SortTable<T>(IQueryable<T> q, string sortfield, bool ascending) { var p = Expression.Parameter(typeof(T), "p"); if (typeof(T).GetProperty(sortfield).PropertyType == typeof(int?)) { var x = Expression.Lambda<Func<T, int?>>(Expression.Property(p, sortfield), p); if (ascending) q = q.OrderBy(x); else q = q.OrderByDescending(x); } else if (typeof(T).GetProperty(sortfield).PropertyType == typeof(int)) { var x = Expression.Lambda<Func<T, int>>(Expression.Property(p, sortfield), p); if (ascending) q = q.OrderBy(x); else q = q.OrderByDescending(x); } else if (typeof(T).GetProperty(sortfield).PropertyType == typeof(DateTime)) { var x = Expression.Lambda<Func<T, DateTime>>(Expression.Property(p, sortfield), p); if (ascending) q = q.OrderBy(x); else q = q.OrderByDescending(x); } // many more for every type return q; } Is there any way I can collapse those ifs to a single generic statement? The main problem is that for the part Expression.Lambda<Func<T, int>> I am not sure how to write it generically.

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  • How to apply a function to a collection of elements

    - by Cue
    Consider I have an array of elements out of which I want to create a new 'iterable' which on every next applies a custom 'transformation'. What's the proper way of doing it under python 2.x? For people familiar with Java, the equivalent is Iterables#transform from google's collections framework.

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  • pluralize function in ruby NOT RAILS!

    - by DJTripleThreat
    Writing some ruby code (not rails) and I need to handle something like this: found 1 match found 2 matches I have rails installed so maybe I might be able to add a require clause at the top of the script, but does anyone know of a RUBY method that pluralizes strings? Is there a class I can require that can deal with this if the script isn't rails but I have rails installed? Thanks in advance!

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  • Python new-style classes and __subclasses__ function

    - by Fraser Graham
    Can somebody explain to me why this works (in Python 2.5) : class Foo(object): pass class Bar(Foo): pass print(Foo.__subclasses__()) but this doesn't : class Foo(): pass class Bar(Foo): pass print(Foo.__subclasses__()) The latter returns "AttributeError: class Foo has no attribute '__subclasses__'" but i'm not sure why. I know this is related to old-style vs. new-style classes but i'm not clear on why that would make this functionality unavailable.

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  • boost variant static_visitor problem picking correct function

    - by Steve
    I'm sure I'm having a problem with template resolution here, but I'm not sure why I'm having the problem. I have a static visitor I'm passing to boost variant where i've had to do template specialization for certain cases. The case for everything except for MyClass should throw in the static_visitor below. Unfortunately, when the visitor is applied to pull a MyClass out, it selects the most generic case rather than the exact match. I would type each case explicitly, but that will be rather long. So, why is the compiler resolving the most generic case over the exact match, and is there anyway to fix it template<> class CastVisitor<MyClass>:public boost::static_visitor<MyClass> { public: template<typename U> MyClass operator()(const U & i) const { throw std::exception("Unable to cast"); } MyClass operator()(const MyClass& i) { return i; } };

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  • C Newbie, ascii control function

    - by user570607
    Hey there, I have written a program that works well in C that converts non-readable ASCII to their character values. I would appreciate if a C master? would show me a better way of doing it that I have currently done, mainly this section: if (isascii(ch)) { switch (ch) { case 0: printControl("NUL"); break; case 1: printControl("SOH"); break; .. etc (32 in total) case default: putchar(ch); break; } } Is it normal to make a switch that big? Or should I be using some other method (input from an ascii table?)

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  • Question about Benchmark function in Mysql ( Incredible results ).

    - by xRobot
    I have 2 tables: author with 3 millions of rows. book with 20 miles rows. . So I have benchmarked this query with a join: SELECT BENCHMARK(100000000, 'SELECT book.title, author.name FROM `book` , `author` WHERE book.id = author.book_id ') And this is the result: Query took 0.7438 sec ONLY 0.7438 seconds for 100 millions of query with a join ??? Do I make some mistakes or this is the right result ?

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  • Data Structure / Hash Function to link Sets of Ints to Value

    - by Gaminic
    Given n integer id's, I wish to link all possible sets of up to k id's to a constant value. What I'm looking for is a way to translate sets (e.g. {1, 5}, {1, 3, 5} and {1, 2, 3, 4, 5, 6, 7}) to unique values. Guarantees: n < 100 and k < 10 (again: set sizes will range in [1, k]). The order of id's doesn't matter: {1, 5} == {5, 1}. All combinations are possible, but some may be excluded. All sets and values are constant and made only once. No deletes or inserts, no value updates. Once generated, the only operations taking place will be look-ups. Look-ups will be frequent and one-directional (given set, look up value). There is no need to sort (or otherwise organize) the values. Additionally, it would be nice (but not obligatory) if "neighboring" sets (drop one id, add one id, swap one id, etc) are easy to reach, as well as "all sets that include at least this set". Any ideas?

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  • Boost shared_ptr use_count function

    - by photo_tom
    My application problem is the following - I have a large structure foo. Because these are large and for memory management reasons, we do not wish to delete them when processing on the data is complete. We are storing them in std::vector<boost::shared_ptr<foo>>. My question is related to knowing when all processing is complete. First decision is that we do not want any of the other application code to mark a complete flag in the structure because there are multiple execution paths in the program and we cannot predict which one is the last. So in our implementation, once processing is complete, we delete all copies of boost::shared_ptr<foo>> except for the one in the vector. This will drop the reference counter in the shared_ptr to 1. Is it practical to use shared_ptr.use_count() to see if it is equal to 1 to know when all other parts of my app are done with the data. One additional reason I'm asking the question is that the boost documentation on the shared pointer shared_ptr recommends not using "use_count" for production code.

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  • creating buttion and calling function on its onclick event using javascript

    - by Deven
    hello friends sorry for previous question actuly my question is i am having one button called btn[0] which is allready on browser when it is loaded when i click on btn[0] it will create another button element called btn[1] now btn[0]'s click event is disabled and when i click on btn[1] it will also generate another button which called btn[2] when i click on btn[2] it will generate another btn called btn[3] and so on

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