C++ Gurus

• 

  Unsolved Question about QThread and how thread work in general.
  • Factao

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  @Factao I think what @kshegunov tried to tell you is that in most cases signals/slots are enough and the right way in Qt to communicate between threads. Low level multi-threading is indeed a complex topic, but nobody here forbids you to learn it. But it is not really possible to explain it in a post in a forum. You should look for tutorials/books.
  Regarding locking for read access see https://doc.qt.io/qt-5/qreadwritelock.html

• 

  Unsolved OpenNN memory problem
  • redmello

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  Here is my code:

  // System includes #include <iostream> #include <fstream> #include <sstream> #include <string> #include <cstring> #include <time.h> // OpenNN includes #include "../../opennn/opennn.h" #include <levenberg_marquardt_algorithm.h> #include <quasi_newton_method.h> using namespace OpenNN; int main(void) { try { int rank = 0; #ifdef __OPENNN_MPI__ int size = 1; MPI_Init(NULL,NULL); MPI_Comm_size(MPI_COMM_WORLD, &size); MPI_Comm_rank(MPI_COMM_WORLD, &rank); #endif if(rank == 0) { std::cout << "OpenNN. Airfoil Self-Noise Application." << std::endl; } srand((unsigned)time(NULL)); // Global variables DataSet data_set; NeuralNetwork neural_network; LossIndex loss_index; TrainingStrategy training_strategy; // Local variables DataSet local_data_set; NeuralNetwork local_neural_network; LossIndex local_loss_index; TrainingStrategy local_training_strategy; if(rank == 0) { // Data set data_set.set_data_file_name("../data/temprenetinputs11.csv"); // controllare dati data_set.set_separator("Space"); data_set.load_data(); printf("%s\n","data_set"); std::cout << typeid(data_set).name() << std::endl; // Variables Variables* variables_pointer = data_set.get_variables_pointer(); variables_pointer->set_name(0, "1"); variables_pointer->set_units(0, "pip"); variables_pointer->set_use(0, Variables::Input); variables_pointer->set_name(1, "2"); variables_pointer->set_units(1, "pip"); variables_pointer->set_use(1, Variables::Input); variables_pointer->set_name(2, "3"); variables_pointer->set_units(2, "pip"); variables_pointer->set_use(2, Variables::Input); variables_pointer->set_name(3, "4"); variables_pointer->set_units(3, "pip"); variables_pointer->set_use(3, Variables::Input); variables_pointer->set_name(4, "5"); variables_pointer->set_units(4, "pip"); variables_pointer->set_use(4, Variables::Input); variables_pointer->set_name(5, "6"); variables_pointer->set_units(5, "pip"); variables_pointer->set_use(5, Variables::Input); variables_pointer->set_name(6, "7"); variables_pointer->set_units(6, "pip"); variables_pointer->set_use(6, Variables::Input); variables_pointer->set_name(7, "8"); variables_pointer->set_units(7, "pip"); variables_pointer->set_use(7, Variables::Input); variables_pointer->set_name(8, "9"); variables_pointer->set_units(8, "pip"); variables_pointer->set_use(8, Variables::Input); variables_pointer->set_name(9, "10"); variables_pointer->set_units(9, "pip"); variables_pointer->set_use(9, Variables::Input); variables_pointer->set_name(10, "11"); variables_pointer->set_units(10, "pip"); variables_pointer->set_use(10, Variables::Input); variables_pointer->set_name(11, "12"); variables_pointer->set_units(11, "pip"); variables_pointer->set_use(11, Variables::Input); variables_pointer->set_name(12, "13"); variables_pointer->set_units(12, "pip"); variables_pointer->set_use(12, Variables::Input); variables_pointer->set_name(13, "14"); variables_pointer->set_units(13, "pip"); variables_pointer->set_use(13, Variables::Input); variables_pointer->set_name(14, "15"); variables_pointer->set_units(14, "pip"); variables_pointer->set_use(14, Variables::Input); variables_pointer->set_name(15, "16"); variables_pointer->set_units(15, "pip"); variables_pointer->set_use(15, Variables::Input); variables_pointer->set_name(16, "17"); variables_pointer->set_units(16, "pip"); variables_pointer->set_use(16, Variables::Input); variables_pointer->set_name(17, "18"); variables_pointer->set_units(17, "pip"); variables_pointer->set_use(17, Variables::Input); variables_pointer->set_name(18, "19"); variables_pointer->set_units(18, "pip"); variables_pointer->set_use(18, Variables::Input); variables_pointer->set_name(19, "20"); variables_pointer->set_units(19, "pip"); variables_pointer->set_use(19, Variables::Input); variables_pointer->set_name(20, "21"); variables_pointer->set_units(20, "pip"); variables_pointer->set_use(20, Variables::Input); variables_pointer->set_name(21, "22"); variables_pointer->set_units(21, "pip"); variables_pointer->set_use(21, Variables::Input); variables_pointer->set_name(22, "23"); variables_pointer->set_units(22, "pip"); variables_pointer->set_use(22, Variables::Input); variables_pointer->set_name(23, "24"); variables_pointer->set_units(23, "pip"); variables_pointer->set_use(23, Variables::Input); variables_pointer->set_name(24, "25"); variables_pointer->set_units(24, "pip"); variables_pointer->set_use(24, Variables::Input); variables_pointer->set_name(25, "26"); variables_pointer->set_units(25, "pip"); variables_pointer->set_use(25, Variables::Input); variables_pointer->set_name(26, "27"); variables_pointer->set_units(26, "pip"); variables_pointer->set_use(26, Variables::Input); variables_pointer->set_name(27, "28"); variables_pointer->set_units(27, "pip"); variables_pointer->set_use(27, Variables::Input); variables_pointer->set_name(28, "29"); variables_pointer->set_units(28, "pip"); variables_pointer->set_use(28, Variables::Input); variables_pointer->set_name(29, "30"); variables_pointer->set_units(29, "pip"); variables_pointer->set_use(29, Variables::Input); variables_pointer->set_name(30, "31"); variables_pointer->set_units(30, "pip"); variables_pointer->set_use(30, Variables::Input); variables_pointer->set_name(31, "32"); variables_pointer->set_units(31, "pip"); variables_pointer->set_use(31, Variables::Input); variables_pointer->set_name(32, "33"); variables_pointer->set_units(32, "pip"); variables_pointer->set_use(32, Variables::Input); variables_pointer->set_name(33, "34"); variables_pointer->set_units(33, "pip"); variables_pointer->set_use(33, Variables::Input); variables_pointer->set_name(34, "35"); variables_pointer->set_units(34, "pip"); variables_pointer->set_use(34, Variables::Input); variables_pointer->set_name(35, "36"); variables_pointer->set_units(35, "pip"); variables_pointer->set_use(35, Variables::Input); variables_pointer->set_name(36, "37"); variables_pointer->set_units(36, "pip"); variables_pointer->set_use(36, Variables::Input); variables_pointer->set_name(37, "38"); variables_pointer->set_units(37, "pip"); variables_pointer->set_use(37, Variables::Input); variables_pointer->set_name(38, "39"); variables_pointer->set_units(38, "pip"); variables_pointer->set_use(38, Variables::Input); variables_pointer->set_name(39, "40"); variables_pointer->set_units(39, "pip"); variables_pointer->set_use(39, Variables::Input); variables_pointer->set_name(40, "41"); variables_pointer->set_units(40, "pip"); variables_pointer->set_use(40, Variables::Input); variables_pointer->set_name(41, "42"); variables_pointer->set_units(41, "pip"); variables_pointer->set_use(41, Variables::Input); variables_pointer->set_name(42, "43"); variables_pointer->set_units(42, "pip"); variables_pointer->set_use(42, Variables::Input); variables_pointer->set_name(43, "target"); variables_pointer->set_use(43, Variables::Target); const Matrix<std::string> inputs_information = variables_pointer->arrange_inputs_information(); const Matrix<std::string> targets_information = variables_pointer->arrange_targets_information(); // Instances Instances* instances_pointer = data_set.get_instances_pointer(); instances_pointer->split_random_indices(); //instances_pointer->split_random_indices(0.7, 0.15, 0.15); const Vector< Statistics<double> > inputs_statistics = data_set.scale_inputs_minimum_maximum(); // mapminmax const Vector< Statistics<double> > targets_statistics = data_set.scale_targets_minimum_maximum(); // Neural network const size_t inputs_number = variables_pointer->count_inputs_number(); const size_t hidden_perceptrons_number = 100; const size_t outputs_number = variables_pointer->count_targets_number(); neural_network.set(inputs_number, hidden_perceptrons_number, outputs_number); // quale funzione di attivazione? //NeuralNetwork neural_network(inputs_number, hidden_perceptrons_number, outputs_number); // validation ?? Inputs* inputs = neural_network.get_inputs_pointer(); inputs->set_information(inputs_information); Outputs* outputs = neural_network.get_outputs_pointer(); outputs->set_information(targets_information); neural_network.construct_scaling_layer(); ScalingLayer* scaling_layer_pointer = neural_network.get_scaling_layer_pointer(); scaling_layer_pointer->set_statistics(inputs_statistics); scaling_layer_pointer->set_scaling_method(ScalingLayer::NoScaling); neural_network.construct_unscaling_layer(); UnscalingLayer* unscaling_layer_pointer = neural_network.get_unscaling_layer_pointer(); unscaling_layer_pointer->set_statistics(targets_statistics); unscaling_layer_pointer->set_unscaling_method(UnscalingLayer::NoUnscaling); // Loss index loss_index.set_data_set_pointer(&data_set); loss_index.set_neural_network_pointer(&neural_network); // mse?? loss_index.set_regularization_type(LossIndex::NEURAL_PARAMETERS_NORM); // ?? // Training strategy object training_strategy.set(&loss_index); //TrainingStrategy training_strategy(&neural_network, &data_set); // non sono i dati // Error :OpenNN Exception: TrainingStrategy class. // LevenbergMarquardtAlgorithm* get_Levenberg_Marquardt_algorithm_pointer(void) const method. // Levenberg_Marquardt algorithm pointer is NULL. // ottenere il valore esatto del pointer es.:0.0000 // CASE 2 ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// LevenbergMarquardtAlgorithm* Levenberg_Marquardt_algorithm_pointer = training_strategy.get_Levenberg_Marquardt_algorithm_pointer(); Levenberg_Marquardt_algorithm_pointer->set_maximum_iterations_number(1000); Levenberg_Marquardt_algorithm_pointer->set_display_period(10); Levenberg_Marquardt_algorithm_pointer->set_minimum_loss_increase(1.0e-6); Levenberg_Marquardt_algorithm_pointer ->set_reserve_loss_history(true); // CASE 1 /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// QuasiNewtonMethod* quasi_Newton_method_pointer = training_strategy.get_quasi_Newton_method_pointer(); quasi_Newton_method_pointer->set_maximum_iterations_number(1000); quasi_Newton_method_pointer->set_display_period(10); quasi_Newton_method_pointer->set_minimum_loss_increase(1.0e-6); quasi_Newton_method_pointer->set_reserve_loss_history(true); // /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// } #ifdef __OPENNN_MPI__ MPI_Barrier(MPI_COMM_WORLD); local_data_set.set_MPI(&data_set); local_neural_network.set_MPI(&neural_network); local_loss_index.set_MPI(&local_data_set,&local_neural_network,&loss_index); local_training_strategy.set_MPI(&local_loss_index,&training_strategy); MPI_Barrier(MPI_COMM_WORLD); TrainingStrategy::Results training_strategy_results = local_training_strategy.perform_training(); #else TrainingStrategy::Results training_strategy_results = training_strategy.perform_training(); #endif if(rank == 0) { #ifdef __OPENNN_MPI__ neural_network.set_multilayer_perceptron_pointer(local_neural_network.get_multilayer_perceptron_pointer()); #endif // Testing analysis TestingAnalysis testing_analysis(&neural_network, &data_set); TestingAnalysis::LinearRegressionResults linear_regression_results = testing_analysis.perform_linear_regression_analysis(); // Save results ScalingLayer* scaling_layer_pointer = neural_network.get_scaling_layer_pointer(); UnscalingLayer* unscaling_layer_pointer = neural_network.get_unscaling_layer_pointer(); scaling_layer_pointer->set_scaling_method(ScalingLayer::MinimumMaximum); unscaling_layer_pointer->set_unscaling_method(UnscalingLayer::MinimumMaximum); data_set.save("../data/data_set.xml"); neural_network.save("../data/neural_network.xml"); neural_network.save_expression("../data/expression.txt"); loss_index.save("../data/loss_index.xml"); training_strategy.save("../data/training_strategy.xml"); training_strategy_results.save("../data/training_strategy_results.dat"); linear_regression_results.save("../data/linear_regression_analysis_results.dat"); } #ifdef __OPENNN_MPI__ MPI_Barrier(MPI_COMM_WORLD); MPI_Finalize(); #endif return(0); } catch(std::exception& e) { std::cerr << e.what() << std::endl; std::getchar(); return(1); } } // OpenNN: Open Neural Networks Library. // Copyright (C) 2005-2015 Roberto Lopez. // // This library is free software; you can redistribute it and/or // modify it under the terms of the GNU Lesser General Public // License as published by the Free Software Foundation; either // version 2.1 of the License, or any later version. // // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU // Lesser General Public License for more details. // You should have received a copy of the GNU Lesser General Public // License along with this library; if not, write to the Free Software // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA[0_1552982666677_main.cpp](Uploading 100%)

  Thanks!

• 

  Unsolved Number Type Cast
  • beecksche

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  @Kent-Dorfman This is a new one on me --- try to write code in one language so it will also work in another :)

• 

  Unsolved How to increase speed of large for loops
  • kane9x

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  I'm surprised no one bit on pointer access of the array elements instead of using array indexing throughout. Pointer access is usually faster than array indexing, but that is an implementation specific detail. I'd also replace pow() with pure multiplication of the terms as (x*x),

• 

  Unsolved inherited classes and const members
  • mzimmers

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  @JonB said in inherited classes and const members:

  @Kent-Dorfman
  Briefly:

  first school computer use: DEC pdp-8 (via model33 teletype) and pdp-11 via la120 decwriter

  Excellent --- someone must actually be older than me! :)

  first president voted for: You guessed it....

  Eisenhower?

  Nah. the one who quoted the term "evil empire" to defer communism/socialism for another 30 years, while at the same time breaking organized labor in the US, and who looked cool as a muppet dressed as superman.

• 

  Snprintf usage&#63;
  • Psycho_Path

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  @Morbius said in Snprintf usage&#63;:

  If you want Unicode, you have to use STL:
  wchar_t buf[4];
  std::swprintf(buf, 4, L"foo");
  qDebug() << QString().fromWCharArray(buf);

  No, you don't. You can simply do qDebug() << QStringLiteral(u"foo");, and please don't use wchar_t if you don't have to. It's not portable and annoying. There are modern replacements like char16_t.

• 

  Solved Loops, Constructors and Performance
  • beecksche

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  This disables eliding - the optimization you're after. So the expression:

  Object a = Object(x, y, z);

  is going to always invoke the copy constructor with that flag. On the other hand -felide-constructors may or may not generate a constructor call depending on the specific version and optimizations the compiler does.

• 

  Solved How to write data to TcpSocket from another thread?
  • Sencis

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  Thank you all for your help, the signals really work fine and now i can easily pass the calibration data of the magnetometer! The truth is everything works in one thread with a timer but the delay is not big.

• 

  Solved Declaring static helper methods in a class
  • JonB

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  @JonB said in Declaring static helper methods in a class:

  C does not segfault. Programmers write code which segfaults!

  That's what I meant, yes.

  Are you saying you have written TV-interface-code in FORTRAN?!

  Oh, don't get me started ...

• 

  Unsolved Begin to learn and work with c ++
  • miken92

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  Hi
  Have a look at
  C++ Without Fear:
  http://brianoverland.com/books/

  if you want a really beginner start.
  However, if you can already program in any language it might start too
  basic :)

• 

  Solved PIMPL for Multiple Inheritance
  • ModelTech

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  @kshegunov Thanks for your clarification! Very much appreciated. Indeed, I avoid the diamond situation in any case and therefore also for QObject. I have just used doxygen to generate a class diagram (inheritance graph) for my architecture at the moment.

• 

  Solved std::string error
  • mzimmers

  27
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  they were referring to/pointing to 2 different object types. I'd expect C++ to have been stricter about that...

  It'd depend on the compiler really, but from the machine's point of view it's all the same. Everything is/is converted to an address to some region in memory. Type-safety is something people invented to have at least some idea about what we are working with, and I agree, the compiler should've warned you at least. But, well, as I said almost everything decays to void * and from there the step into the abyss is just tiny ... ;)

• 

  This topic is deleted!
  • mrdebug

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• 

  Unsolved Friendship with method of other class in other File
  • Josz

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  @karlheinzreichel solution requires mySubClass to know the full definition of myClass. You can't just pre-declare class myClass; //forward declaration is needed

  An alternative is

  class FriendHelper{ public: static void actualPrint(myClass& sender); };

  now move the body of void print(); inside the body of actualPrint and change it to void print() {FriendHelper::actualPrint(*this);}

  No you can make FriendHelper a friend of both myClass and mySubClass

• 

  Solved Link errors; Connect a Signal of an object in main.cpp to a Slot in an object in MainWindow.cpp
  • Josz

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  @SGaist said in Link errors; Connect a Signal of an object in main.cpp to a Slot in an object in MainWindow.cpp:

  AFAIK

  I don't know. I have a .pro and a .pri. For me was needed.

  here is my .pro

  QT += core gui charts greaterThan(QT_MAJOR_VERSION, 4): QT += widgets TARGET = drawRange TEMPLATE = app include(drawRangeGUI/drawRangeGUI.pri) include(hmisg/hmisg.pri) INCLUDEPATH += tmp/moc/release_shared DEFINES += QT_DEPRECATED_WARNINGS CONFIG += c++11 SOURCES += \ main.cpp HEADERS += FORMS += \ # Default rules for deployment. qnx: target.path = /tmp/$${TARGET}/bin else: unix:!android: target.path = /opt/$${TARGET}/bin !isEmpty(target.path): INSTALLS += target DISTFILES += \ drawRangeGUI/drawrange.pri

  and my .pri

  INCLUDEPATH += $$PWD \ $$PWD/erpc-1.7.1/erpc_c/port \ $$PWD/erpc-1.7.1/erpc_c/infra \ $$PWD/erpc-1.7.1/erpc_c/setup \ $$PWD/erpc-1.7.1/erpc_c/config \ $$PWD/erpc-1.7.1/erpc_c/transports DEPENDPATH += $$PWD \ $$PWD/erpc-1.7.1/erpc_c/port \ $$PWD/erpc-1.7.1/erpc_c/infra \ $$PWD/erpc-1.7.1/erpc_c/setup \ $$PWD/erpc-1.7.1/erpc_c/config \ $$PWD/erpc-1.7.1/erpc_c/transports HEADERS += \ $$PWD/hmisg.h \ $$PWD/erpc-1.7.1/erpc_c/setup/erpc_server_setup.h \ $$PWD/erpc-1.7.1/erpc_c/setup/erpc_client_setup.h \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_basic_codec.h \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_client_manager.h \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_codec.h \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_common.h \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_crc16.h \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_framed_transport.h \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_manually_constructed.h \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_message_buffer.h \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_server.h \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_simple_server.h \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_transport.h \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_version.h \ $$PWD/erpc-1.7.1/erpc_c/setup/erpc_mbf_setup.h \ $$PWD/erpc-1.7.1/erpc_c/setup/erpc_transport_setup.h \ $$PWD/erpc-1.7.1/erpc_c/config/erpc_config.h \ $$PWD/erpc-1.7.1/erpc_c/port/erpc_config_internal.h \ $$PWD/erpc-1.7.1/erpc_c/port/erpc_port.h \ $$PWD/erpc-1.7.1/erpc_c/port/erpc_threading.h \ $$PWD/erpc-1.7.1/erpc_c/transports/erpc_tcp_transport_win.h SOURCES += \ $$PWD/hmisg.cpp \ $$PWD/erpc-1.7.1/erpc_c/setup/erpc_server_setup.cpp \ $$PWD/erpc-1.7.1/erpc_c/setup/erpc_client_setup.cpp \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_basic_codec.cpp \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_client_manager.cpp \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_crc16.cpp \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_framed_transport.cpp \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_message_buffer.cpp \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_server.cpp \ $$PWD/erpc-1.7.1/erpc_c/infra/erpc_simple_server.cpp \ $$PWD/erpc-1.7.1/erpc_c/setup/erpc_setup_mbf_dynamic.cpp \ $$PWD/erpc-1.7.1/erpc_c/setup/erpc_setup_tcp.cpp \ $$PWD/erpc-1.7.1/erpc_c/port/erpc_threading_windows.cpp \ $$PWD/erpc-1.7.1/erpc_c/transports/erpc_tcp_transport_win.cpp

  regards

• 

  Unsolved Pointer to SubObject Member
  • Josz

  5
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  @Josz

  //(mO.mS.*pSOprint)(); //don't work

  Where is your MySubObject::pSOprint defined and initialized to MySubObject::print(), if that's what you're trying to do?

  m0.(*pSOprint)(); //dont work, I would like to make anything so

  Similarly for MyObject::pSOprint? [And btw that m0 should be mO.]

  In your original you have

  void (MyObject::*pointerToPrint)() = &MyObject::print; //<- I make here a function pointer to own methrod

  Where are you doing the equivalent of this for the function you want to access in your MySubObject? I'm not C++, but don't you need something like one of (hopefully the first):

  void (MyObject::*pSOPrint)() = &MySubObject::print; void (MyObject::*pSOPrint)() = &MyObject::mS::print;

  Also, when you say "don't work" for things, it would save a lot of guessing if you said it doesn't compile/crashes/doesn't do what you want/... :)

• 

  Unsolved Is it possible to use static arrays in std Algorithms?
  • Engelard

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  To summarise: std::begin() and std::end() are the way to go

• 

  Solved How to write a common callback function?
  • Mr Pang

  3
  3
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  @JKSH
  Great! I never thought of it before.

• 

  Unsolved unable to open or create a project with QT creator
  • tesnime

  2
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  Hi and welcome to devnet,

  What version of Qt are you using ?
  What version of Qt Creator are you using ?
  How did you install them ?
  What OS are you running on ?
  What compiler are you using ?

• 

  Solved scope problems
  • CharlesHuff

  6
  6
  Posts
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  Qt is just C++. Creating a SysManager object in each function might not be the best idea. Having one instance in your class will make you code cleaner. Note that this doesn't apply to every situation.

• 

  Unsolved Recursiveness in "catch enter key" example?
  • Josz

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  You're welcome!

• 

  Solved Algorithm to find all possible combinations
  • DavidM29

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  https://en.wikipedia.org/wiki/Constraint_programming and https://en.wikipedia.org/wiki/Gecode?

• 

  Solved How to implement Oscilloscope for realtime-plotting?
  • _bhum

  4
  4
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  @_bhum Ok, so Qwt library should help. You may want to use one of the examples I mentioned (i.e. the one from MagPi magazine) as a guideline to what/how they draw on screen (I know, it's Python code but it will help...)

• 

  This topic is deleted!
  • chmod

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  No one has replied

• 

  Unsolved How does programs like Fraps or Dxtory get FPS?
  • Engelard

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  No one has replied

• 

  Unsolved Default special member binary compatibility
  • VRonin

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  @Konstantin-Tokarev said in Default special member binary compatibility:

  That's wrong

  Ok, I was told the opposite and I have the maximum respect for your and David's opinion so I don't know who to believe anymore :(

• 

  Unsolved QObject::connect: No such slot Widget::on_lineEdit_textEdited()
  • Rahul.k

  6
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  Hi,

  You wrote:
  @Rahul.k said in QObject::connect: No such slot Widget::on_lineEdit_textEdited():

  QObject::connect(arduino,SIGNAL(readyRead()),this,SLOT(on_lineEdit_textEdited()));

  Yet your slot implementation signature is:
  @Rahul.k said in QObject::connect: No such slot Widget::on_lineEdit_textEdited():

  void Widget::on_lineEdit_textEdited(const QString)

  So which one is the correct ?

  In any case, that name is completely misleading with respect to what that function does and to what it's connected to. Thus you should rather give it a proper name.

• 

  Unsolved Seismic Model code runs in CodeBlocks but not in Qt.
  c++ seismic modell academic stuff research • • Flavio Mesquita

  5
  5
  Posts
  426
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  Are you implementing technique number 4 described here ?

• 

  Rants about auto
  • jsulm

  25
  25
  Posts
  1283
  Views

  

  @JonB said in Rants about auto:

  And the relevance of it being specifically zsh is... what?

  Environment of the interpreter.

  You just looking for extra points?

  Yep! Gimme, gimme!

• 

  Solved QRegExp. Extract sentence containing keyword to the end
  • mandruk1331

  3
  3
  Posts
  323
  Views

  

  Hello,

  I have tried your variant it returns string which I do not need. I am parsing out an HTML code of the page. When I run you variant it returns all kind of string, and I only need the sentence where the "[error]" key word is present.

  Update:
  This variant of RegExp works like a charm:

  \\[error\\](.*)

  Thank you for your time. The issue has been resolved

• 

  Unsolved Letting the User set the respective directory within a qt wigdet application
  • Pippapo

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  7
  Posts
  451
  Views

  

  @JonB Thank you so much for your reply. I am sorry I did not get back to you sooner, life kept me busy. I'll get right back to my project and I'm really thankful for your help and the information you provided.

• 

  This topic is deleted!
  • nasir

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  Posts
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• 

  Unsolved C++ - Can't access function in another class
  • mad-hatter

  18
  18
  Posts
  1181
  Views

  

  Hi @mad-hatter

  Is there something I should add in the header file?

  That would help to resolve compile errors, when the compiler cannot find the definition of a function.

  Linker errors mean, the linker cannot find the implementation of the function.

  Usually this means either the implementation is missing in your source file or you have it in a source file that is not compiled/linked.

  Regards

• 

  Solved C++ % " ?
  • JonB

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  Posts
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  @JKSH said in C++ % " ?:

  Wait till you try + or += on QJsonArray ;)

  QJsonArray a1{1, 2, 3}; QJsonArray a2{4, 5, 6}; a1 += a2; // a1 now has 4 elements: 3 numbers and 1 array

  😑😔
  of course it does.

  Not a fan!

• 

  Solved QSettings ini format special chars in key
  • 6thC

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  Posts
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  @6thC said in QSettings ini format special chars in key:

  @JonB you mean me specifically or it's been discussed before, I don't remember but me forgetting something wouldn't be the first time that's happened. I did search quite a bit so got the feeling this was the case.

  Gosh, no! I meant the "Royal We" :) I recall answering about this in another thread a while ago (e.g. https://forum.qt.io/topic/92858/logging-rules-in-ini-file-with-qsetting-and-asterisk/2 and https://forum.qt.io/topic/91362/how-to-edit-a-ini-file/11).

  As @sierdzio said, the .ini file support from QSettings is only for its own puprposes. All it really guarantees is that you can read back a file that it has written. You may be able to read an external .ini file, but if you write it back it can change to non-.ini format. Remember Qt is platform-independent, and the files you are talking about are really Windows-only.

• 

  Unsolved TableView background color
  • Mogli123

  3
  3
  Posts
  392
  Views

  

  @Mogli123
  just to make sure: indexes are 0-based. So first row/column has an index of 0 not 1.
  In case you only showing 1 row of data in your table and wondering why the background doesn't get applied.

• 

  Unsolved QSharedDataPointer detach too much ( don't call const )
  • miskol

  2
  2
  Posts
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  Views

  

  @miskol It outputs 2 times "bbb". Why do you think there is a detach in your example?

• 

  Solved how to write PID control algorithm to control temperature
  • _bhum

  9
  9
  Posts
  925
  Views

  

  @_bhum said in how to write PID control algorithm to control temperature:

  how i execute my program on raspi terminal????

  do you know how to run a program in a Linux terminal?

• 

  Unsolved How to use QTimer connect without Object and without slot
  • mrudula

  3
  3
  Posts
  523
  Views

  

  Hi,
  You can use QTimer with lamda functions like this.

  connect(pTimerValidateScheduleTimeoutr, &QTimer::timeout, []() { ValidateScheduleEvent(); });
• 

  Unsolved Is this intentional?
  • digital_light

  3
  3
  Posts
  460
  Views

  

  @digital_light said in Is this intentional?:

  Why are we defining Ui::LoadScreen and ::LoadScreen? Doesn't that defeat the purpose of the namespace?

  They are 2 separate classes.

  ::LoadScreen is your "actual" class where you write your code Ui::LoadScreen is a fully auto-generated class that's embedded inside ::LoadScreen.