C++ Gurus

• 

  Solved template/macro for reducing redundant functions?
  • fcarney

  10
  10
  Posts
  73
  Views

  

  @fcarney said in template/macro for reducing redundant functions?:

  Okay, I think I get it.

  Partly. What a template is from the point of view of the binary is nothing - it does not produce anything. A template is way to tell your compiler to substitute template arguments at some point and produce a real living class (or function) which it then can compile to assembly. Instantiation happens on first use with a given set of template parameters ordinarily. In this case I "abuse" that peculiarity by saying: okay, there is a template function (the declaration) but when you need to substitute the types (i.e. instantiate the template on use) you can't, because you don't know the function body.

  The extern template at the end is to make all that at all useful - fine there's no body, so the template can't be instantiated in the user code, but I can give you some instantiations I made explicitly somewhere else (in this case in the source). So it works like this:

  The compiler sees there's a declaration. It also sees there are 2, 3, 4 instantiations that are done somewhere else (i.e. the declarations at the bottom). In the source it has the template body, and has been told to instantiate the template - that's fine, it can as it knows how. When you use it somewhere it matches the stuff that's declared (i.e. the template declaration and the instantiations) against what you request. It puts a reference for the linker to resolve. If there's an instantiation provided for the given set of template parameters, everything is fine - the linker's going to clean up the mess and link the function you have with the usage. If not, i.e. you used the template with a parameter that hand't been explicitly instantiated, then the linker complains - there's no such thing.
• 

  Solved Functor without warnings
  • casperbear

  5
  5
  Posts
  88
  Views

  

  @Konstantin-Tokarev It worked. Thank you. I had been looking at that warning for months. Final solution didn't require to move pure virtual function's definition to *.cpp. I'll leave it here for future seekers.
  DLL *.pro

  DEFINES += APPLICATIONMODEL_LIBRARY

  DLL and EXE *.h

  #ifdef APPLICATIONMODEL_LIBRARY # define APPLICATIONMODEL_EXPORT Q_DECL_EXPORT #else # define APPLICATIONMODEL_EXPORT Q_DECL_IMPORT #endif

  DLL *.h

  class APPLICATIONMODEL_EXPORT CActionFunctor { public: virtual ~CActionFunctor(); virtual void operator()() = 0; }; template <typename TClass> class TActionFunctor : public CActionFunctor { public: TActionFunctor(TClass *object, void(TClass::*function)()) { Object = object; Function = function; } void operator()() { (*Object.*Function)(); } private: TClass *Object; void (TClass::*Function)(); };

  DDL *.cpp

  CActionFunctor::~CActionFunctor() { } APPLICATIONMODEL_EXPORT CActionFunctor *SimulationInstanceChanged = nullptr; void CSimulation::Bind(CSimulation **simulation) { *simulation = this; (*SimulationInstanceChanged)(); }

  EXE *.cpp

  APPLICATIONMODEL_EXPORT CActionFunctor *SimulationInstanceChanged; WMain::WMain() { SimulationInstanceChanged = new TActionFunctor<WMain>(this, &WMain::OnSimulationInstanceChanged); }
• 

  Solved Warning: overrides a destructor but is not marked 'override'
  • saurabh162

  11
  11
  Posts
  124
  Views

  

  Hello @JonB, @J-Hilk, @Konstantin-Tokarev,

  Once again thank you very much for your help.

  Now I have understood it correctly.

• 

  Solved Passing reference of class from call on class
  • fcarney

  6
  6
  Posts
  103
  Views

  

  @kshegunov
  Well the use case was to match the interface currently being used to provide variables to the tr() (translate functions). We have code that looks like this:

  tr("Log Message","Status: %1").arg(2)

  Well the problem with this is the string is in a server and the client needs to translate the message. So I wanted to wrap the message in a similar way and use the same arg() interface we currently use.

  JMsg(QT_TRANSLATE_NOOP("Log Message","Hello: %1 %2 %3")).arg(1).arg("full").arg("world");

  The JMsg overloads an operator:

  operator QString(){return toString();}

  This allows the call to be very similar to the original tr() call and return a string to the function it is created in. JMsg is intended to be a temporary variable. The string it produces is a JSON string that embeds the message with parameters and the args in a list. This is decoded by the client and translated using a function designed to interpret the JSON code.

  So effectively I am modeling it after how the translate parameter system works, for the API anyway. Not the underlying code.

  I don't program javascript or java much. Mainly C++ and Python.

• 

  Solved Containers with C++17 structured bindings
  • david_dlqa

  13
  13
  Posts
  179
  Views

  

  @J.Hilk
  Thanks, that makes sense. I just copied that from the documentation hence I thought that was not a concern.
  I reran the tests and got almost the same results, so I think with times in the seconds, the qDebug overhead is not significant

• 

  Solved Signal/slot and const parameters
  • KroMignon

  11
  11
  Posts
  110
  Views

  

  @VRonin said in Signal/slot and const parameters:

  Mixed feeling about this. Qt internally will const_cast the sender if the signal is const

  :O I had no idea.

• 

  Unsolved OpenCL won't run while debugging
  • beecksche

  6
  6
  Posts
  116
  Views

  

  Both suggestions don't work.

  I don't think the code is incorrect, i found many other examples uses the same part of code. The docs also says, that the function will ignore the pointer if it's NULL.

  Unfortunetaly i'm not able to update my Intel Graphics Driver to the newest release. Maybe that's the reason.

  Nevertheless, I tried a lot of OpenCL kernels, which will work correctly in Release mode.

  I also can skip the exception in Debug mode by continue the debugging twice, and the functions return the correct result.

  In Visual Studio the same exception is caused in the ntdll.exe. But this is also not helpfull for me to find the problem.

  Keep searching.

• 

  Solved from int to double
  • vale88

  6
  6
  Posts
  151
  Views

  

  @J.Hilk thanks

• 

  Solved Creating call back functions for a library
  • Yaswanth

  18
  18
  Posts
  284
  Views

  

  I could use member function of class as a callback.
  I have sent function object which is returned by std::bind to the library . In library used std::function to hold bind expression.
  So as per the data, respective callback functions can be called.

• 

  Solved Memory fragmentation
  • casperbear

  13
  13
  Posts
  329
  Views

  

  @casperbear said in Memory fragmentation:

  Yeah, you caught me. I'm inclined to use heap because I'm primarily a C# developer. Sounds like I need to learn that move semantics after all, to use stack approach more effectively.

  free store memory management is a whole field of study unto itself, so yes...research research research.

  @kshegunov -- Well put. You saved me from posting what could have inadvertantly turned into a rant. LOL

• 

  Solved prohibiting duplicate connections?
  • Kent-Dorfman

  10
  10
  Posts
  266
  Views

  

  At least not here, because we don't know the deep details.

  It's a twofold problem:

  The connect needs a context QObject, if not specified that's the sender.
  Then the question becomes is the following the same connection: QObject * otherObject; void freeFunction(); QObject::connect(this, &MyClass::someSignal, otherObject, freeFunction); QObject::connect(this, &MyClass::someSignal, this, freeFunction);

  where, conceivably, otherObject may be in a different thread. Nobody knows how these two should be distinguished exactly - in some cases they may be considered the same, in some they may not. freeFunction isn't attached to the class of this, nor to the class of otherObject.

  A functor (a.k.a. lamda, a.k.a. function object, std::function, etc.) more often than not has (internal) state. So two instances of the same type (i.e. two lambdas) can't be distinguished due to the fact that the state is not known to Qt. Example: auto functor1 = [this] () -> void { qDebug() << "Functor"; } auto functor2 = functor1; //< Object copy here! We are dealing with another entity entirely! QObject::connect(this, &MyClass::someSignal, this, functor1); QObject::connect(this, &MyClass::someSignal, this, functor2); //< functor2 isn't functor1

  And to add insult to injury:

  QObject::connect(this, &MyClass::someSignal, this, functor1); //< Object copy of functor1! QObject::connect(this, &MyClass::someSignal, this, functor1); //< Object copy of functor1, again!
• 

  Solved How does Qt::connectiontype work?
  • Factao

  5
  5
  Posts
  195
  Views

  

  Thank you!

• 

  Unsolved QPrint no possible to set page size and orientation (ubuntu 18.04)
  • gfxx

  11
  11
  Posts
  321
  Views

  

  Ran your code on:

  Ubuntu 18.04 64 bit Qt 5.12.2 gcc

  I get paper and orientation outputs consistent with my selections. I tried 3 variations.
  Edit:
  Output: print to pdf

• 

  Unsolved QImage from QDatastream of float values
  • connecting_dots

  4
  4
  Posts
  168
  Views

  

  What kind of images are that in the first place ?
  Where do they come from ?

• 

  Solved Violation of MISRA08_18-4-1
  • Phadnis

  6
  6
  Posts
  172
  Views

  

  @Kent-Dorfman Thanks I agree.

• 

  Solved Number Type Cast
  • beecksche

  21
  21
  Posts
  706
  Views

  

  @jsulm , @SGaist

  thanks a lot. I thought I had understood the problem. But it seems to be a bit more complicated.

  Hopefully, in some time, I will understande when to use which cast explicitly and for what reason.

  Until thenI hope that these parts of the code don't make any trouble.

• 

  Solved Is there 'findChild<>()' but for simple variables?
  • Engelard

  6
  6
  Posts
  170
  Views

  

  the long and short of this issue is that if you want to "find" an object in Qt then you need that object ot be a sublclass of QObject. So, if you want to use it for ordinal/simple/immutable variables then you need to create special classes that wrap those variables and derive from QObject.

  HOWEVER!!!! trying to do this really deontes a poor design and you should reevaluate your reason for doing so.

• 

  Solved Qt with eclipse C++
  • GastonMelo

  6
  6
  Posts
  282
  Views

  

  When last I looked at the Qt plugin for eclipse it was hopelessly broken. At the time eclipse had a lot of problems parsing the Qt framework include files and MOC system for code checking. Are you using the plugin, or just using eclipse as an editor?

• 

  Solved "nested name specifier" error
  • mzimmers

  8
  8
  Posts
  254
  Views

  

  OK, thanks for the education...they're all removed and the warnings have disappeared.

• 

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

  32
  32
  Posts
  1011
  Views

  

  Perhaps, but I don't see an implication for the case of signal-slot connections vs direct synchronization ... at the end of the day the former still uses a mutex to serialize access to the queued events ...

• 

  OpenNN memory problem
  • redmello

  3
  3
  Posts
  143
  Views

  

  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 How to increase speed of large for loops
  • kane9x

  30
  30
  Posts
  1475
  Views

  

  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

  27
  27
  Posts
  788
  Views

  

  @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

  10
  10
  Posts
  5372
  Views

  

  @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

  19
  19
  Posts
  927
  Views

  

  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

  11
  11
  Posts
  464
  Views

  

  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

  14
  14
  Posts
  413
  Views

  

  @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

  3
  3
  Posts
  286
  Views

  

  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

  6
  6
  Posts
  580
  Views

  

  @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
  27
  Posts
  1349
  Views

  

  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

  3
  3
  Posts
  6
  Views
• 

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

  6
  6
  Posts
  575
  Views

  

  @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

  9
  9
  Posts
  753
  Views

  

  @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
  5
  Posts
  461
  Views

  

  @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

  6
  6
  Posts
  510
  Views

  

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

• 

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

  3
  3
  Posts
  416
  Views

  

  @JKSH
  Great! I never thought of it before.

• 

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

  2
  2
  Posts
  286
  Views

  

  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
  594
  Views

  

  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

  4
  4
  Posts
  399
  Views

  

  You're welcome!

• 

  Solved Algorithm to find all possible combinations
  • DavidM29

  6
  6
  Posts
  628
  Views

  

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