Recent questions tagged c++

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c++ - How does std::enabled_if work when enabling via a parameter

I'm trying to understand how enable_if works and I understand almost everything except scenario #3 from https://en. ... Why is it pointer ? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Native Message received, but response failed

I am developing a macOS application which can communicate with google chrome extension through native messaging. I ... same in both situations. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to use Boost::Geometry _union with integers

I'm trying to use Boost::Geometry _union with integers, for both performance and numeric accuracy. For that, I ... Y coordinate in the input. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Time Complexity of this double loop

What will be the time complexity of this code? for(int i = 1 ; i <= b ; ++i ) for(int j = i ; j <= b ; j += i ) See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - My program has unexpectedly finished

this simplest program gives error when compiled in release mode, but compiles fine in debug mode: #include < ... Anyone had this experience? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - LoadLibrary failed with error code 126 if app started from installation option

I have two application and install in different folders, let call it app A and B, A is main application and B ... ; //failed with error code 126 See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to fix error "GLib-GIO-ERROR**: No GSettings schemas are installed on the system"?

I have to create a one-file (.exe) program with InstallShield2015LimitedEdition that works with GTK3.4.2 and ... variable. Is this correct? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - What would a CRTP-based solution to this look like?

I asked the following question in this post (pasted below for convenience). One of the comments suggested that ... two and three base classes. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How can unspecified types be used in C++20 'requires' expressions?

I'm trying to write a C++20 concept to express the requirement that a type have a certain method, which takes an ... does not apply to my case. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - boost::spirit binding function providing parameteres as spirit:qi::_val

There is a need of providing the values from an object of type boost::variant for an std::pair object. How would ... list-redux technic > '}'; See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Why is the address of a local variable identical for different executions?

int fun(int x); int main() { fun(10); fun(11); return 0; } int fun(int x) { int loc;//local ... is the address &loc same for both the execution? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Convert Cimg to ITK

I'm trying to convert a Cimg image to itk image to use it for registration algorithm. The Cimg is a RGB image ... *, size_t) What is wrong?? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Destruction of QObjects

My program sometimes gives Segmentation Fault at the last statement in main function. return a.exec(); I ... it causes segmentation fault. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Why does false sharing still affect non atomics, but much less than atomics?

Consider the following example that proves false sharing existence: using type = std::atomic<std::int64_t>; struct alignas(128) ... .b << ' '; } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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600 views

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c++ - Directshow Preview Only and Capture & Preview with a single Graph

I have a Directshow application that needs to preview a webcam video, and when user clicks 'Record' it needs to ... is the right approach here? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - cannot find default constructor to initialize member in cpp

Please help me with this. I was trying to fix this for two hours. This is my code. class deviceC ... in function deviseC::destination(wayPoint) See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - call system() return 256

I want to system() to print pstack info in my application, but it failed and return 256.But I pick up these ... app`,retValue:%d",retValue); } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Memory management in allocating 2-D array

I have allocated a two dimensional array using the following code: // Dynamic allocation int **matrix=new int*[n] ... correct way of doing it? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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607 views

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c++ cli - String conversion from System::String ^ to const wchar_t *

I'm trying to open a file using a string parameter, however I'm getting the following error: error C2664: 'void ... String ^ to const wchar_t *? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS does not cover global variables

Porting a C++ library, under CMake, to Windows. Option 1: Decorate the API with __declspec(dllexport). Option ... app.cpp: extern int my_secret; See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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561 views

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c++ - static variable initialisation code never gets called

I've got an application that's using a static library I made. One .cpp file in the library has a static variable ... but I don't know what.. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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673 views

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c++ - Is it possible to use SIMD instruction for replace?

I have vector of int and I need to find and replace some elements with specific value. Both of them are the same. For ... [0] * i0))[i1]; } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Template singleton base class in shared object

I'm currently porting my project from Windows to Linux. The project consists of a 'main' shared library, several ... didn't solve the problem. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to set SparseMatrix.valuePtr(), SparseMatrix.outerIndexPtr() and SparseMatrix.innerIndexPtr() for CSR Format?

I already have my sparse matrix data in CSR format, ie: I already have data for non zero values ( in the form ... , if this is possible at all? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ initialize array with declared size as a value of an integer

I want to initialize an array with a size using a value I read into an integer variable. I cant seem to understand ... it ... thanks a lot! See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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468 views

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c++ - How do I rotate my camera correctly in my 3D world?

Im triyng to learn 3d programming and Im currently working on a FPS camera-style for a hobby project. I've ... to do with the rotation itself. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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445 views

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c++ - The label type must be float if you want to read the xml files of random forest(opencv3.0)

#include <opencv2/core.hpp> #include <opencv2/ml.hpp> #include <iostream> #include <vector> int main() { size_t ... cv::ml::DTreesImpl::calcDir" See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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761 views

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c++ cli - Linking error while in C++/CLI project while wrapping C++ shared library

I am trying to wrap C++ library to that managed projects can use it. The third party library I am ... or more multiply defined symbols found See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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