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  • C++: Binding to a base class

    - by Helltone
    The following code works, but I'm not sure it is correct/portable. #include <iostream> #include <tr1/functional> class base { public: base(int v) : x(v) {} protected: int x; }; class derived : public base { public: bool test() { return (x == 42); } }; int main(int argc, char* argv[]) { base b(42); if(std::tr1::bind((bool (base::*)()) &derived::test, b)()) { std::cout << "ok\n"; } return 0; }

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  • Alternative to latex / a way to typeset good looking documents from Java to PDF

    - by drasto
    I'm working on application in Java that will maintain database of song lyrics in plain text and print out some songbooks/chordbooks(that is create PDF file from selected songs). I was planing that the Java application will generate source code for pdflatex and after compiling this source user will get PDF file. Lately I've run into a lot of problems because of latex limitation: fixed memory size (some pictures will also be drawn to PDF) - error when exceeded, no way to query end of line or and of page dynamically, it's very hard to override latex placement algorithm in a complex way,... see also some my other questions regarding latex. I come to conclusion that latex is not good option for automated PDF generation. So I need replacement. I need to be able to typeset: Chords over lyrics when the lyrics are in variable char width so I need to be able to measure text width Chord diagrams that means I'll have to draw quite complex pictures Each song on separate double page Different fonts etc. Thanks for all answers

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  • insert data into several tables

    - by csetzkorn
    Let us say I have a table (everything is very much simplified): create table OriginalData ( bla char(10) not null ) And I would like to insert its data (set based!) into two tables which model inheritance create table Statements ( Id int IDENTITY NOT NULL, ProposalDateTime DATETIME null ) create table Items ( StatementFk INT not null, ItemName NVARCHAR(255) null, primary key (StatementFk) ) Statements is the parent table and Items is the child table. I have no problem doing this with one row which involves the use of IDENT_CURRENT but I have no idea how to do this set based (i.e. enter several rows into both tables). Thanks. Best wishes, Christian

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  • Better way of enforcing this template?

    - by Dennis Ritchie
    Currently, I have a function template like this that converts a vector into a string (just a natural string, separating the elements with a comma): //the type T must be passable into std::to_string template<typename T> std::string vec_to_str(const std::vector<T> &vec); As you can see, this is only meant for vectors whose elements can be passed into the built-in std::to_string function (such as int, double, etc.) Is it considered a good practice to document with comments the allowed T? If not, what should I do? Is it possible to enforce this in a better way?

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  • ASP.NET 3.5 Page character encoding problem

    - by Dorian McHensie
    Hello everyone. I have a problem in my asp.net 3.5 application (C#) when I try to render in my pages characters like 'è' which are shown in a very strange manner (if i'm lucky i get a ? mark in my web page). in fact Expression Web, when i open my web site, substitutes the è char with �... How can I tell asp.net that I want to use a particular charset so that i can write in the html source letters like è without using hexadecimal codes?????? I tried in the web.config this: inside the system.web namespace of the file but nothing works.... Can anyone tell me how to do? THANKS in advance

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  • APP CAN'T LAUNCH IN XCODE

    - by user2977180
    I'm beginning to code in xCode 5 and I'm doing a really simple app. I just began and, when I try to test my game with iOS Simulator, the main page opens, but when I click on the button to launch the game, I'm redirected to xCode and this appears: #import "AppDelegate.h" #import "AppDelegate.h" int main(int argc, char * argv[]) { @autoreleasepool { return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class])); } } and just next to it, this is written: Thread 1 : Signal SIGABRT I searched on internet and I just can't seem to find an answer. Could someone help me please???

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  • Can't delete a file created by mkstemp() on Mac OS X

    - by splicer
    Apparently, NSFileManager is unable to delete files created by mkstemp(). Here's some test code to demonstrate this: char pathCString[] = "/tmp/temp.XXXXXX"; int fileDescriptor = mkstemp(pathCString); if (fileDescriptor == -1) { NSLog(@"mkstemp failed"); } else { close(fileDescriptor); NSURL *url = [NSURL URLWithString:[NSString stringWithCString:pathCString encoding:NSASCIIStringEncoding]]; NSLog(@"URL: %@", url); NSError *error; if (![[NSFileManager defaultManager] removeItemAtURL:url error:&error]) { NSLog(@"could not delete file: %@", error); } } Here's what I see in the log when I run the above code: URL: /tmp/temp.A7DsLW could not delete file: Error Domain=NSCocoaErrorDomain Code=4 UserInfo=0x1001108a0 "The file “temp.A7DsLW” doesn’t exist." I'm running this on Snow Leopard. Any ideas on why the problem is occurring and/or how to work around it? Thanks!

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  • How to serialize a data of type string without using StringWriter as input

    - by starz26
    I want to serialize a input data of type string, but do not want to use StringWriter and StringReader for for serializing/Deserializing. The reason for this is when a escapse chars are sent as part of the Input string for serializing, it is serialized but some Spl chars are inserted in the xml(eg:"").I'm getting an XMl error while deserializing this serialized data. void M1() { string str = 23 + "AC"+(char)1; StringWriter sw = new StringWriter(); XmlSerializer serializer = new XmlSerializer(typeof(String)); serializer.Serialize(sw, str); System.Console.WriteLine("String encoded to XML = \n{0} \n", sw.ToString()); StringReader sr = new StringReader(sw.ToString()); String s2 = (String)serializer.Deserialize(sr); System.Console.WriteLine("String decoded from XML = \n {0}", s2); }

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  • An easy way to replace fread()'s with reading from a byte array?

    - by Sam Washburn
    I have a piece of code that needs to be run from a restricted environment that doesn't allow stdio (Flash's Alchemy compiler). The code uses standard fopen/fread functions and I need to convert it to read from a char* array. Any ideas on how to best approach this? Does a wrapper exist or some library that would help? Thanks! EDIT: I should also mention that it's reading in structs. Like this: fread(&myStruct, 1, sizeof(myStruct), f);

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  • C++0x, How do I expand a tuple into variadic template function arguments?

    - by Gustaf
    Consider the case of a templated function with variadic template arguments: template<typename Tret, typename... T> Tret func(const T&... t); Now, I have a tuple t of values. How do I call func() using the tuple values as arguments? I've read about the bind() function object, with call() function, and also the apply() function in different some now-obsolete documents. The GNU GCC 4.4 implementation seems to have a call() function in the bind() class, but there is very little documentation on the subject. Some people suggest hand-written recursive hacks, but the true value of variadic template arguments is to be able to use them in cases like above. Does anyone have a solution to is, or hint on where to read about it?

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  • C++, create an instance from a static method

    - by Manux
    Hello, let's say I want my users to use only one class, say SpecialData. Now, this data class would have many methods, and depending on the type of data, the methods do different things, internally, but return externally similar results. Therefore my wanting to have one "public" class and other "private", child classes that would change the behavior of methods, etc... It would be amazingly more simple for some types of data that need to be built to do something like this: SpecialData& sm = SpecialData::new_supermatrix(); and new_supermatrix() would return a SuperMatrix instance, which inherits from most behaviors of SpecialData. my header: static SpecialData& new_supermatrix(); my cpp: SpecialData& SpecialData::new_supermatrix()(){ return SuperMatrix(MATRIX_DEFAULT_MAGNITUDE,1000,1239,FLOAT32,etc...); } The problem is, I get this error, which is probably logical due to the circumstances: invalid initialization of non-const reference of type ‘SpecialData&’ from a temporary of type ‘SpecialData’ So, any ideas?

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  • Simple wrapping of C code with cython

    - by Jose
    Hi, I have a number of C functions, and I would like to call them from python. cython seems to be the way to go, but I can't really find an example of how exactly this is done. My C function looks like this: void calculate_daily ( char *db_name, int grid_id, int year, double *dtmp, double *dtmn, double *dtmx, double *dprec, double *ddtr, double *dayl, double *dpet, double *dpar ) ; All I want to do is to specify the first three parameters (a string and two integers), and recover 8 numpy arrays (or python lists. All the double arrays have N elements). My code assumes that the pointers are pointing to an already allocated chunk of memory. Also, the produced C code ought to link to some external libraries.

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  • pointer delegate in STL set.

    - by ananth
    hi. Im kinda stuck with using a set with a pointer delegate. my code is as follows: void Graph::addNodes (NodeSet& nodes) { for (NodeSet::iterator pos = nodes.begin(); pos != nodes.end(); ++pos) { addNode(*pos); } } Here NodeSet is defined as: typedef std::set NodeSet; The above piece of code works perfectly on my windows machine, but when i run the same piece of code on a MAC, it gives me the following error: no matching function for call to 'Graph::addNode(const boost::shared_ptr&)' FYI, Node_ptr is of type: typedef boost::shared_ptr Node_ptr; can somebody plz tell me why this is happening?

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  • 1 bug to kill... Letting PHP Generate The Canonical.

    - by Sam
    Hi folks, for building a clean canonical url, that always returns 1 base URL, im stuck in following case: <?php # every page $extensions = $_SERVER['REQUEST_URI']; # path like: /en/home.ast?ln=ja $qsIndex = strpos($extensions, '?'); # removes the ?ln=de part $pageclean = $qsIndex !== FALSE ? substr($extensions, 0, $qsIndex) : $extensions; $canonical = "http://website.com" . $pageclean; # basic canonical url ?> <html><head><link rel="canonical" href="<?=$canonical?>"></head> when URL : http://website.com/de/home.ext?ln=de canonical: http://website.com/de/home.ext BUT I want to remove the file extension aswell, whether its .php, .ext .inc or whatever two or three char extension .[xx] or .[xxx] so the base url becomes: http://website.com/en/home Aaah much nicer! but How do i achieve that in current code? Any hints are much appreciated +! (other advices for proper canonical usage in this multi-lingual environment are welcome as well)

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  • Matrix multiplication using Matrix Template library (MTL 4)

    - by Lxc
    The program is as following: #include <iostream> #include <boost/numeric/mtl/mtl.hpp> using namespace mtl; int main(int argc, char* argv[]) { dense_vector<double> a(5,1.0); dense_vector<double> b(5,2.0); a * trans(b); } I want to calculate a * trans(b), but there is a compling error :C2893. Will someone help me? Thanks a lot!

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  • problem in reading output of dd command using pipe

    - by Ummar
    I am developing an application, in which I want to redirect the output (progress information) of dd command to my C++ program, but it is not actually getting the output, here is the code FILE * progressInfo = popen("gzip -dc backup/backup.img.gz | pv -ptrbe -i 2 -s 2339876653 | dd of=/dev/sdb","r"); if(!progressInfo) { return -1; } char buf[1024]; while(fgets(buff, sizeof(buff),progressInfo)!=NULL) { std::cout << buff << endl; } but the problem is the progress information is not received in buff, and the output is continuously printed on terminal, and above program halts on while(fgets(buff, sizeof(buff),progressInfo)!=NULL), and as soon as the dd operation is completed, the very next line to loop block is executed. if anyone has any idea why the output is not returned to buff, and its continuously retuned on terminal?

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  • Is a switch statment ok for 30 or so conditions?

    - by DeanMc
    I am in the final stages of creating an MP4 tag parser in .Net. For those who have experience with tagging music you would be aware that there are an average of 30 or so tags. If tested out different types of loops and it seems that a switch statement with Const values seems to be the way to go with regard to catching the tags in binary. The switch allows me to search the binary without the need to know which order the tags are stored or if there are some not present but I wonder if anyone would be against using a switch statement for so many conditionals. Any insight is much appreciated.

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  • undefined reference to static member variable

    - by Max
    Hi. I have this class that has a static member. it is also a base class for several other classes in my program. Here's its header file: #ifndef YARL_OBJECT_HPP #define YARL_OBJECT_HPP namespace yarlObject { class YarlObject { // Member Variables private: static int nextID; // keeps track of the next ID number to be used int ID; // the identifier for a specific object // Member Functions public: YarlObject(): ID(++nextID) {} virtual ~YarlObject() {} int getID() const {return ID;} }; } #endif and here's its implementation file. #include "YarlObject.hpp" namespace yarlObject { int YarlObject::nextID = 0; } I'm using g++, and it returns three undefined reference to 'yarlObject::YarlObject::nextID linker errors. If I change the ++nextID phrase in the constructor to just nextID, then I only get one error, and if I change it to 1, then it links correctly. I imagine it's something simple, but what's going on?

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  • How to detect tab key pressing in C#?

    - by user342325
    I want to detect when tab key is pressed in a textBox and focus the next textbox in the panel. I have tried out keyPressed method and keyDown method. But when I run the program and debug those methods are not calling when the tab key is pressed. Here is my code. private void textBoxName_KeyDown(object sender, KeyEventArgs e) { if (e.KeyCode == Keys.Tab) { textBoxUsername.Focus(); } } private void textBoxName_KeyPress(object sender, KeyPressEventArgs e) { if (e.KeyChar==(char)Keys.Tab) { textBoxUsername.Focus(); } } Please correct me.Thank you.

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  • write() in sys/uio.h returns -1

    - by fredrik
    I'm using Ubuntu Server 9.10 AMD Phenom 2 cpu g++ (Ubuntu 4.4.1-4ubuntu9) 4.4.1 trying to run the application pftp-shit v 1.11. The following code in tcp.cc is executed successfully: int outfile_fd = open(name, O_CREAT | O_TRUNC | O_RDWR | O_BINARY)) which returns a file descriptor int (in my case 6) - name is a char array containing a valid path to my file which successfully i created. and successfully running: fchmod(outfile_fd, S_IRUSR | S_IWUSR); and access(name, W_OK) The issue occurs during running the function (from sys/uio.h) write(outfile_fd, this-control_buffer, read_length) which returns -1. -1 is of returned if nothing was written and otherwise a non-negative integer is returned which is equal to the number of bytes written. Anyone having a clue how I can get the write function to work?

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  • Reducing template bloat with inheritance

    - by benoitj
    Does anyone have experience reducing template code bloat using inheritance? i hesitate rewriting our containers this way: class vectorBase { public: int size(); void clear(); int m_size; void *m_rawData; //.... }; template< typename T > class vector : public vectorBase { void push_back( const T& ); //... }; I should keep maximum performance while reducing compile time I'm also wondering why stl implementations do not uses this approach Thanks for your feedbacks

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  • C++'s unordered_map / hash_map / Google's dense_hash - how to input binary data (buf+len) and insert

    - by shlomif
    Hi all, I have two questions about Google's dense_hash_map, which can be used instead of the more standard unordered_map or hash_map: How do I use an arbitrary binary data memory segment as a key: I want a buffer+length pair, which may still contain some NUL (\0) characters. I can see how I use a NUL-terminated char * string , but that's not what I want. How do I implement an operation where I look if a key exists, and if not - insert it and if it does return the pointer to the existing key and let me know what actually happened. I'd appreciate it if anyone can shed any light on this subject. Regards, -- Shlomi Fish

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  • C++: Template functor cannot deduce reference type

    - by maciekp
    I've got a functor f, which takes a function func and a parameter t of the same type as func. I cannot pass g to f because of compilation error (no matching function for call to f(int&, void (&)(int&)) ). If g would take non-reference parameter g(int s), compilation finishes. Or if I manually specify template parameter f(i, g), compilation also finishes. template<typename T> void f(T t, void (*func)(T)) {} void g(int& s) {} int main(int, char*[]) { int i = 7; f(i, g); // compilation error here return 0; } How can I get deduction to work?

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  • Please explain syntax rules and scope for "typedef"

    - by unknown google user
    What are the rules? OTOH the simple case seems to imply the new type is the last thing on a line. Like here Uchar is the new type. typedef unsigned char Uchar; But a function pointer is completely different. Here the new type is pFunc: typedef int (*pFunc) (int); I can't think of any other examples offhand but I have come across some very confusing usages. So are there rules or are people just suppose to know from experience that this is how it is done because they have seen it done this way before? ALSO: What is the scope of a typedef. Thanks to everyone.

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  • How to update records based on sum of a field then use the sum to calc a new value in sql

    - by Casey
    Below is what i'm trying to do with by iterating through the records. I would like to have a more elegant solution if possible since i'm sure this is not the best way to do it in sql. set @counter = 1 declare @totalhrs dec(9,3), @lastemp char(7), @othrs dec(9,3) while @counter <= @maxrecs begin if exists(select emp_num from #tt_trans where id = @counter) begin set @nhrs = 0 set @othrs = 0 select @empnum = emp_num, @nhrs = n_hrs, @othrs = ot_hrs from #tt_trans where id = @counter if @empnum = @lastemp begin set @totalhrs = @totalhrs + @nhrs if @totalhrs > 40 begin set @othrs = @othrs + @totalhrs - 40 set @nhrs = @nhrs - (@totalhrs - 40) set @totalhrs = 40 end end else begin set @totalhrs = @nhrs set @lastemp = @empnum end update #tt_trans set n_hrs = @nhrs, ot_hrs = @othrs where id = @counter and can_have_ot = 1 end set @counter = @counter + 1 end Thx

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