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  • Boost::thread mutex issue: Try to lock, access violation

    - by user1419305
    I am currently learning how to multithread with c++, and for that im using boost::thread. I'm using it for a simple gameengine, running three threads. Two of the threads are reading and writing to the same variables, which are stored inside something i call PrimitiveObjects, basicly balls, plates, boxes etc. But i cant really get it to work, i think the problem is that the two threads are trying to access the same memorylocation at the same time, i have tried to avoid this using mutex locks, but for now im having no luck, this works some times, but if i spam it, i end up with this exception: First-chance exception at 0x00cbfef9 in TTTTT.exe: 0xC0000005: Access violation reading location 0xdddddded. Unhandled exception at 0x77d315de in TTTTT.exe: 0xC0000005: Access violation reading location 0xdddddded. These are the functions inside the object that im using for this, and the debugger is also blaming them for the exception. void PrimitiveObj::setPos(glm::vec3 in){ boost::mutex mDisposingMutex; boost::try_mutex::scoped_try_lock lock(mDisposingMutex); if ( lock) { position = in; boost::try_mutex::scoped_try_lock unlock(mDisposingMutex); } } glm::vec3 PrimitiveObj::getPos(){ boost::mutex myMutex; boost::try_mutex::scoped_try_lock lock(myMutex); if ( lock) { glm::vec3 curPos = position; boost::try_mutex::scoped_try_lock unlock(myMutex); return curPos; } return glm::vec3(0,0,0); } Any ideas?

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  • Using boost::iterator_adaptor

    - by Neil G
    I wrote a sparse vector class (see #1, #2.) I would like to provide two kinds of iterators: The first set, the regular iterators, can point any element, whether set or unset. If they are read from, they return either the set value or value_type(), if they are written to, they create the element and return the lvalue reference. Thus, they are: Random Access Traversal Iterator and Readable and Writable Iterator The second set, the sparse iterators, iterate over only the set elements. Since they don't need to lazily create elements that are written to, they are: Random Access Traversal Iterator and Readable and Writable and Lvalue Iterator I also need const versions of both, which are not writable. I can fill in the blanks, but not sure how to use boost::iterator_adaptor to start out. Here's what I have so far: class iterator : public boost::iterator_adaptor< iterator // Derived , value_type* // Base , boost::use_default // Value , boost::?????? // CategoryOrTraversal > class sparse_iterator : public boost::iterator_adaptor< iterator // Derived , value_type* // Base , boost::use_default // Value , boost::random_access_traversal_tag? // CategoryOrTraversal >

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  • How can I use Boost::regex.hpp library in C++?

    - by MIH1406
    I tried to use Boost library but I failed, see my code: #include "listy.h" #include <boost/regex.hpp> using namespace boost; ListyCheck::ListyCheck() { } ListyCheck::~ListyCheck() { } bool ListyCheck::isValidItem(std::string &__item) { regex e("(\\d{4}[- ]){3}\\d{4}"); return regex_match(__item, e); } When I tried to compile it I get those messages: /usr/include/boost/regex/v4/regex_match.hpp:50: undefined reference to `boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator, std::allocator , std::allocator, std::allocator , boost::regex_traits ::match()' /usr/include/boost/regex/v4/basic_regex.hpp:425: undefined reference to `boost::basic_regex ::do_assign(char const*, char const*, unsigned int)' /usr/include/boost/regex/v4/perl_matcher.hpp:366: undefined reference to `boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator, std::allocator , std::allocator, std::allocator , boost::regex_traits ::construct_init(boost::basic_regex const&, boost::regex_constants::_match_flags)' etc...

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  • Is code that terminates on a random condition guaranteed to terminate?

    - by Simon Campbell
    If I had a code which terminated based on if a random number generator returned a result (as follows), would it be 100% certain that the code would terminate if it was allowed to run forever. while (random(MAX_NUMBER) != 0): // random returns a random number between 0 and MAX_NUMBER print('Hello World') I am also interested in any distinctions between purely random and the deterministic random that computers generally use. Assume the seed is not able to be known in the case of the deterministic random. Naively it could be suggested that the code will exit, after all every number has some possibility and all of time for that possibility to be exercised. On the other hand it could be argued that there is the random chance it may not ever meet the exit condition-- the generator could generate 1 'randomly' until infinity. (I suppose one would question the validity of the random number generator if it was a deterministic generator returning only 1's 'randomly' though)

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  • C++ question: boost::bind receive other boost::bind

    - by user355034
    I want to make this code work properly, what should I do? giving this error on the last line. what am I doing wrong? i know boost::bind need a type but i'm not getting. help class A { public: template <class Handle> void bindA(Handle h) { h(1, 2); } }; class B { public: void bindB(int number, int number2) { std::cout << "1 " << number << "2 " << number2 << std::endl; } }; template struct Wrap_ { Wrap_(Han h) : h_(h) {} template<typename Arg1, typename Arg2> void operator()(Arg1 arg1, Arg2 arg2) { h_(arg1, arg2); } Han h_; }; template inline Wrap_<Handler> make(Handler h) { return Wrap_<Handler> (h); } int main() { A a; B b; ((boost::bind)(&B::bindB, b, _1, _2))(1, 2); ((boost::bind)(&A::bindA, a, make(boost::bind(&B::bindB, b, _1, _2))))(); /i want compiled success and execute success this code/ }

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  • c++ generate a good random seed for psudo random number generators

    - by posop
    I am trying to generate a good random seed for a psudo-random number generator. I thought I'd get the expert's opinions. let me know if this is a bad way of doing it or if there are much better ways. #include <iostream> #include <cstdlib> #include <fstream> #include <ctime> unsigned int good_seed() { unsigned int random_seed, random_seed_a, random_seed_b; std::ifstream file ("/dev/random", std::ios::binary); if (file.is_open()) { char * memblock; int size = sizeof(int); memblock = new char [size]; file.read (memblock, size); file.close(); random_seed_a = int(memblock); delete[] memblock; }// end if else { random_seed_a = 0; } random_seed_b = std::time(0); random_seed = random_seed_a xor random_seed_b; return random_seed; } // end good_seed()

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  • How to call shared_ptr<boost::signal> from a vector in a loop?

    - by BTR
    I've got a working callback system that uses boost::signal. I'm extending it into a more flexible and efficient callback manager which uses a vector of shared_ptr's to my signals. I've been able to successfully create and add callbacks to the list, but I'm unclear as to how to actually execute the signals. ... // Signal aliases typedef boost::signal<void (float *, int32_t)> Callback; typedef std::shared_ptr<Callback> CallbackRef; // The callback list std::vector<CallbackRef> mCallbacks; // Adds a callback to the list template<typename T> void addCallback(void (T::* callbackFunction)(float * data, int32_t size), T * callbackObject) { CallbackRef mCallback = CallbackRef(new Callback()); mCallback->connect(boost::function<void (float *, int32_t)>(boost::bind(callbackFunction, callbackObject, _1, _2))); mCallbacks.push_back(mCallback); } // Pass the float array and its size to the callbacks void execute(float * data, int32_t size) { // Iterate through the callback list for (vector<CallbackRef>::iterator i = mCallbacks.begin(); i != mCallbacks.end(); ++i) { // What do I do here? // (* i)(data, size); // <-- Dereferencing doesn't work } } ... All of this code works. I'm just not sure how to run the call from within a shared_ptr from with a vector. Any help would be neat-o. Thanks, in advance.

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  • Linker error when compiling boost.asio example

    - by Alon
    Hi, I'm trying to learn a little bit C++ and Boost.Asio. I'm trying to compile the following code example: #include <iostream> #include <boost/array.hpp> #include <boost/asio.hpp> using boost::asio::ip::tcp; int main(int argc, char* argv[]) { try { if (argc != 2) { std::cerr << "Usage: client <host>" << std::endl; return 1; } boost::asio::io_service io_service; tcp::resolver resolver(io_service); tcp::resolver::query query(argv[1], "daytime"); tcp::resolver::iterator endpoint_iterator = resolver.resolve(query); tcp::resolver::iterator end; tcp::socket socket(io_service); boost::system::error_code error = boost::asio::error::host_not_found; while (error && endpoint_iterator != end) { socket.close(); socket.connect(*endpoint_iterator++, error); } if (error) throw boost::system::system_error(error); for (;;) { boost::array<char, 128> buf; boost::system::error_code error; size_t len = socket.read_some(boost::asio::buffer(buf), error); if (error == boost::asio::error::eof) break; // Connection closed cleanly by peer. else if (error) throw boost::system::system_error(error); // Some other error. std::cout.write(buf.data(), len); } } catch (std::exception& e) { std::cerr << e.what() << std::endl; } return 0; } With the following command line: g++ -I /usr/local/boost_1_42_0 a.cpp and it throws an unclear error: /tmp/ccCv9ZJA.o: In function `__static_initialization_and_destruction_0(int, int)': a.cpp:(.text+0x654): undefined reference to `boost::system::get_system_category()' a.cpp:(.text+0x65e): undefined reference to `boost::system::get_generic_category()' a.cpp:(.text+0x668): undefined reference to `boost::system::get_generic_category()' a.cpp:(.text+0x672): undefined reference to `boost::system::get_generic_category()' a.cpp:(.text+0x67c): undefined reference to `boost::system::get_system_category()' /tmp/ccCv9ZJA.o: In function `boost::system::error_code::error_code()': a.cpp:(.text._ZN5boost6system10error_codeC2Ev[_ZN5boost6system10error_codeC5Ev]+0x10): undefined reference to `boost::system::get_system_category()' /tmp/ccCv9ZJA.o: In function `boost::asio::error::get_system_category()': a.cpp:(.text._ZN5boost4asio5error19get_system_categoryEv[boost::asio::error::get_system_category()]+0x7): undefined reference to `boost::system::get_system_category()' /tmp/ccCv9ZJA.o: In function `boost::asio::detail::posix_thread::~posix_thread()': a.cpp:(.text._ZN5boost4asio6detail12posix_threadD2Ev[_ZN5boost4asio6detail12posix_threadD5Ev]+0x1d): undefined reference to `pthread_detach' /tmp/ccCv9ZJA.o: In function `boost::asio::detail::posix_thread::join()': a.cpp:(.text._ZN5boost4asio6detail12posix_thread4joinEv[boost::asio::detail::posix_thread::join()]+0x25): undefined reference to `pthread_join' /tmp/ccCv9ZJA.o: In function `boost::asio::detail::posix_tss_ptr<boost::asio::detail::call_stack<boost::asio::detail::task_io_service<boost::asio::detail::epoll_reactor<false> > >::context>::~posix_tss_ptr()': a.cpp:(.text._ZN5boost4asio6detail13posix_tss_ptrINS1_10call_stackINS1_15task_io_serviceINS1_13epoll_reactorILb0EEEEEE7contextEED2Ev[_ZN5boost4asio6detail13posix_tss_ptrINS1_10call_stackINS1_15task_io_serviceINS1_13epoll_reactorILb0EEEEEE7contextEED5Ev]+0xf): undefined reference to `pthread_key_delete' /tmp/ccCv9ZJA.o: In function `boost::asio::detail::posix_tss_ptr<boost::asio::detail::call_stack<boost::asio::detail::task_io_service<boost::asio::detail::epoll_reactor<false> > >::context>::posix_tss_ptr()': a.cpp:(.text._ZN5boost4asio6detail13posix_tss_ptrINS1_10call_stackINS1_15task_io_serviceINS1_13epoll_reactorILb0EEEEEE7contextEEC2Ev[_ZN5boost4asio6detail13posix_tss_ptrINS1_10call_stackINS1_15task_io_serviceINS1_13epoll_reactorILb0EEEEEE7contextEEC5Ev]+0x22): undefined reference to `pthread_key_create' collect2: ld returned 1 exit status How can I fix it? Thank you.

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  • What is Boost missing?

    - by Robert Gould
    After spending most of my waking time on Stack Overflow, for better or for worse, I've come to notice how 99% of the C++ questions are answered with "use boost::wealreadysolvedyourproblem", but there must definitely be a few areas Boost doesn't cover, but would be better if it did. So what features is Boost missing? I'll start by saying: boost::sql (although SOCI should try to become a legal part of boost) boost::json (although TinyJSON should try to become a legal part of boost) boost::audio (no idea about a good boost-like C++ library) PS: The purpose is to compile a reasonable list, and hopefully Boost-like solutions out there that aren't yet a part of Boost, so no silly stuff like boost::turkey please.

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  • Gamma Distribution in Boost

    - by Kamchatka
    Hello, I'm trying to use the Gamma distribution from boost::math but it looks like it isn't possible to use it with boost::variate_generator. Could someone confirm that? Or is there a way to use it. I discovered that there is a boost::gamma_distribution undocumented that could probably be used too but it only allows to choose the alpha parameter from the distribution and not the beta. Thanks!

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  • Server side random selection of players

    - by Ron
    Assuming I have a simple client-server game, where the server picks random players on a very frequent base, I was wondering what is the best way to select a random player (According to the following constraints): Solution must be high performance and highly scalable Random spread should be relatively even (meaning if I have 3 players and pick 99 times, they will all be picked 33 times more or less) Should only pick players who were active in the past X days (optional, but a big bonus) The actual DB or data model used to store players isn't an issue here, as we'll select the technology in accordance to our needs. However, high performance and scalability is (at the moment we have over 60,000 unique daily active players, and we plan on growing even more). Thanks!

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  • Make objects slide across the screen in random positions

    - by user3475907
    I want to make an object appear randomly at the right hand side of the screen and then slide across the screen and disapear at the left hand side. I am working with libgdx. I have this bit of code but it makes items fall from the top down. Please help. public EntityManager(int amount, OrthoCamera camera) { player = new Player(new Vector2(15, 230), new Vector2(0, 0), this, camera); for (int i = 0; i < amount; i++) { float x = MathUtils.random(0, MainGame.HEIGHT - TextureManager.ENEMY.getHeight()); float y = MathUtils.random(MainGame.WIDTH, MainGame.WIDTH * 10); float speed = MathUtils.random(2, 10); addEntity(new Enemy(new Vector2(x, y), new Vector2(-0, -speed))); }

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  • Is Unity's Random seeded automatically?

    - by Lohoris
    I seem to recall Unity's Random is automatically seeded; checking the documentation it doesn't say it outright, but a certain interpretation of their words might seem to imply it. The seed is normally set from some arbitrary value like the system clock before the random number functions are used. This prevents the same run of values from occurring each time a game is played and thus avoids predictable gameplay. However, it is sometimes useful to produce the same run of pseudo-random values on demand by setting the seed yourself. (emphasis added)

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  • Boost Thread Specific Storage Question (boost/thread/tss.hpp)

    - by Hassan Syed
    The boost threading library has an abstraction for thread specific (local) storage. I have skimmed over the source code and it seems that the TSS functionality can be used in an application with any existing thread regardless of weather it was created from boost::thread --i.e., this implies that certain callbacks are registered with the kernel to hook in a callback function that may call the destructor of any TSS objects when the thread or process is going out of scope. I have found these callbacks. I need to cache HMAC_CTX's from OpenSSL inside the worker threads of various web-servers (see this, detailed, question for what I am trying to do), and as such I do not controll the life-time of the thread -- the web-server does. Therefore I will use the TSS functionality on threads not created by boost::thread. I just wanted to validate my assumptions before I started implementing the caching logic, are there any flaws in my logic ?

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  • .NET: will Random.Random operate differently inside a static method

    - by Craig Johnston
    I am having difficulty with the following code which is inside a static method of a non-static class. int iRand; int rand; rand = new Random((int)DateTime.Now.Ticks); iRand = rand.Next(50000); The iRand number, along with some other values, are being inserted into a new row of an Access MDB table via OLEDB. The iRand number is being inserted into a field that is part of the primary key, and the insert attempt is throwing the following exception even though the iRand number is supposed to be random: System.Data.OleDb.OleDbException: The changes you requested to the table were not successful because they would create duplicate values in the index, primary key, or relationship. Change the data in the field or fields that contain duplicate data, remove the index, or redefine the index to permit duplicate entries and try again. Could the fact the method is static be making the iRand number stay the same, for some reason?

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  • generate random opacity number using math random

    - by TechyDude
    I am trying to generate a random number for the css opacity. This is what I tried so far. CSS .test{ position : absolute; width : 15px; height : 15px; border-radius:15px; background-color : black; }? Script $(function() { for (var i = 0; i < 300; i++) { $("<div>", { class: "test", css: { opacity: randomOpacity } }).appendTo("body"); } function randomOpacity() { var opac = 0; opac = Math.random() < 1; console.log(opac); } randomize(); });? The Fiddle

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  • Fastest Way to generate 1,000,000+ random numbers in python

    - by Sandro
    I am currently writing an app in python that needs to generate large amount of random numbers, FAST. Currently I have a scheme going that uses numpy to generate all of the numbers in a giant batch (about ~500,000 at a time). While this seems to be faster than python's implementation. I still need it to go faster. Any ideas? I'm open to writing it in C and embedding it in the program or doing w/e it takes. Constraints on the random numbers: A Set of numbers 7 numbers that can all have different bounds: eg: [0-X1, 0-X2, 0-X3, 0-X4, 0-X5, 0-X6, 0-X7] Currently I am generating a list of 7 numbers with random values from [0-1) then multiplying by [X1..X7] A Set of 13 numbers that all add up to 1 Currently just generating 13 numbers then dividing by their sum Any ideas? Would pre calculating these numbers and storing them in a file make this faster? Thanks!

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  • Using system time directly to get random numbers

    - by Richard Mar.
    I had to return a random element from an array so I came up with this placeholder: return codes[(int) (System.currentTimeMillis() % codes.length - 1)]; Now than I think of it, I'm tempted to use it in real code. The Random() seeder uses system time as seed in most languages anyway, so why not use that time directly? As a bonus, I'm free from the worry of non-random lower bits of many RNGs. It this hack coming back to bite me? (The language is Java if that's relevant.)

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  • Does boost::asio makes excessive small heap allocations or am I wrong?

    - by Poni
    #include <cstdlib> #include <iostream> #include <boost/bind.hpp> #include <boost/asio.hpp> using boost::asio::ip::tcp; class session { public: session(boost::asio::io_service& io_service) : socket_(io_service) { } tcp::socket& socket() { return socket_; } void start() { socket_.async_read_some(boost::asio::buffer(data_, max_length - 1), boost::bind(&session::handle_read, this, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred)); } void handle_read(const boost::system::error_code& error, size_t bytes_transferred) { if (!error) { data_[bytes_transferred] = '\0'; if(NULL != strstr(data_, "quit")) { this->socket().shutdown(boost::asio::ip::tcp::socket::shutdown_both); this->socket().close(); // how to make this dispatch "handle_read()" with a "disconnected" flag? } else { boost::asio::async_write(socket_, boost::asio::buffer(data_, bytes_transferred), boost::bind(&session::handle_write, this, boost::asio::placeholders::error)); socket_.async_read_some(boost::asio::buffer(data_, max_length - 1), boost::bind(&session::handle_read, this, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred)); } } else { delete this; } } void handle_write(const boost::system::error_code& error) { if (!error) { // } else { delete this; } } private: tcp::socket socket_; enum { max_length = 1024 }; char data_[max_length]; }; class server { public: server(boost::asio::io_service& io_service, short port) : io_service_(io_service), acceptor_(io_service, tcp::endpoint(tcp::v4(), port)) { session* new_session = new session(io_service_); acceptor_.async_accept(new_session->socket(), boost::bind(&server::handle_accept, this, new_session, boost::asio::placeholders::error)); } void handle_accept(session* new_session, const boost::system::error_code& error) { if (!error) { new_session->start(); new_session = new session(io_service_); acceptor_.async_accept(new_session->socket(), boost::bind(&server::handle_accept, this, new_session, boost::asio::placeholders::error)); } else { delete new_session; } } private: boost::asio::io_service& io_service_; tcp::acceptor acceptor_; }; int main(int argc, char* argv[]) { try { if (argc != 2) { std::cerr << "Usage: async_tcp_echo_server <port>\n"; return 1; } boost::asio::io_service io_service; using namespace std; // For atoi. server s(io_service, atoi(argv[1])); io_service.run(); } catch (std::exception& e) { std::cerr << "Exception: " << e.what() << "\n"; } return 0; } While experimenting with boost::asio I've noticed that within the calls to async_write()/async_read_some() there is a usage of the C++ "new" keyword. Also, when stressing this echo server with a client (1 connection) that sends for example 100,000 times some data, the memory usage of this program is getting higher and higher. What's going on? Will it allocate memory for every call? Or am I wrong? Asking because it doesn't seem right that a server app will allocate, anything. Can I handle it, say with a memory pool? Another side-question: See the "this-socket().close();" ? I want it, as the comment right to it says, to dispatch that same function one last time, with a disconnection error. Need that to do some clean-up. How do I do that? Thank you all gurus (:

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  • Boost::binary<> [c++][Boost]

    - by atch
    Hi, Is there anything in boost libraries like binary? For example I would like to write: binary<10101> a; I'm ashamed to admit that I've tried to find it (Google, Boost) but no results. They're mention something about binary_int< but I couldn't find neither if it is available nor what header file shall I include; Thanks for help.

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  • Random enemy placement on a 2d grid

    - by Robb
    I want to place my items and enemies randomly (or as randomly as possible). At the moment I use XNA's Random class to generate a number between 800 for X and 600 for Y. It feels like enemies spawn more towards the top of the map than in the middle or bottom. I do not seed the generator, maybe that is something to consider. Are there other techniques described that can improve random enemy placement on a 2d grid?

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  • Boost program will not working on Linux

    - by Martin Lauridsen
    Hi SOF, I have this program which uses Boost::Asio for sockets. I pretty much altered some code from the Boost examples. The program compiles and runs just like it should on Windows in VS. However, when I compile the program on Linux and run it, I get a Segmentation fault. I posted the code here The command I use to compile it is this: c++ -I/appl/htopopt/Linux_x86_64/NTL-5.4.2/include -I/appl/htopopt/Linux_x86_64/boost_1_43_0/include mpqs.cpp mpqs_polynomial.cpp mpqs_host.cpp -o mpqs_host -L/appl/htopopt/Linux_x86_64/NTL-5.4.2/lib -lntl -L/appl/htopopt/Linux_x86_64/gmp-4.2.1/lib -lgmp -lm -L/appl/htopopt/Linux_x86_64/boost_1_43_0/lib -lboost_system -lboost_thread -static -lpthread By commenting out code, I have found out that I get the Segmentation fault due to the following line: boost::asio::io_service io_service; Can anyone provide any assistance, as to what may be the problem (and the solution)? Thanks! Edit: I tried changing the program to a minimal example, using no other libraries or headers, just boost/asio.hpp: #define DEBUG 0 #include <boost/asio.hpp> int main(int argc, char* argv[]) { boost::asio::io_service io_service; return 0; } I also removed other library inclusions and linking on compilation, however this minimal example still gives me a segmentation fault.

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  • Biased Random Number Generator

    - by cmptrer
    I am looking for a random number generator that can be biased. For instance, say I want a random number between 1-5, with the probability being: 1: Comes up 20% of the time 2: Comes up 10% of the time 3: Comes up 40% of the time 4: Comes up 25% of the time 5: Comes up 5% of the time Is there anything in the standard library, or other libraries out there that would do this? Alternatively, is there an efficient way to do this myself?

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  • Getting N random numbers that the sum is M

    - by marionmaiden
    Hello I want to get N random numbers that the sum of them is a value. For example, let's suppose I want 5 random numbers that their sum is 1 Then, a valid possibility is: 0.2 0.2 0.2 0.2 0.2 Other possibility is: 0.8 0.1 0.03 0.03 0.04 And so on. I need this for the creation of the matrix of belongings of the Fuzzy C-means.

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