Recent questions tagged C++

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One of the possibilities is: somestringstream.str(""); But is it most optimal? Is there any way to ... require to reserve memory again? 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 does "const class" mean?

After some find and replace refactoring I ended up with this gem: const class A { }; What does "const class" mean? It seems to compile ok. 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 initialize a char array?

char * msg = new char[65546]; want to initialize to 0 for all of them. what is the best way to do this in C++? 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++ - Converting std::unique_ptr<Derived> to std::unique_ptr<Base>

Using C++11, let's say I have factory functions dealing with base and derived classes: #include <memory> using ... even with -std=c++11. 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++ - ifstream: check if opened successfully

A colleague just told me that this code: std::ifstream stream(filename.c_str()); if (!stream) { throw std:: ... Can you point me to 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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c++ - Visual studio 2013 "A task was cancelled"

After installing VS 2013 (Update 3) on windows 7 SP1 I have similar situation like in this post After installing windows ... skipped ========== 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 C++11 constexpr so restrictive?

As you probably know, C++11 introduces the constexpr keyword. C++11 introduced the keyword constexpr, which ... proving function a is pure? 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++ - Prevent Firing Signals in Qt

We have a QCheckBox object, when user checks it or removes check we want to call a function so we ... firing signal under some conditions? 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 so much space allocated on the stack?

This question comes from answering Stack Overflow question Why do books say, the compiler allocates space for variables ... my `double` goes 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++ - Return value optimization and copy elision in C

Some people are not aware that it's possible to pass and return structs by value in C. My question ... is an interesting question nevertheless. 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++ - Makefile improvements, dependency generation not functioning

I'm currently trying to build a proper Makefile. What I want is full control of what's happening, so I ... 't the dependency generation work? 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++ - Getting undefined symbol error while dynamic loading of shared library

I am getting undefined symbol error while loading library dynamically. Here is my code snippet that generates ... help would be appreciated. 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++ - Best DirectShow way to capture image from web cam preview ? SampleGrabber is deprecated

I have developed DirectShow C++ app which successfully previews web cam view into provided window. Now I want to ... from live web cam preview? 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++ - Return bestMove in minimax algorithm for tictactoe

I have tried to code the minimax algorithm for tic-tac-toe given in Russel Norvig's book on Artificial ... http://ideone.com/XPswCl 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 configure project with COMPONENTS in cmake

I want to create a project of projects using cmake which is accessible in a similar manner to that used by ... code now works, thankyou! 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 it not efficient to use a single assignment operator handling both copy and move assignment?

Here is an exercise from C++ Primer 5th Edition: Exercise 13.53: As a matter of low-level efficiency, the HasPtr ... is not efficient to do so? 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++ - Is it possible to create a vector of pointers?

Just wondering, because of a problem I am running into, is it possible to create a vector of pointers? And if so, how ... ++) { citer->func(); } 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++ - Return values for active objects

Back in 2010, Herb Sutter advocated the use of active objects instead of naked threads in an article on Dr. Dobb ... ::future and std::promise. 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++ - IP Camera access using OpenCV

The code given below is for accessing an Axis IP camera using OpenCV. On running the program it first displays " ... Where am I going 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++ - std::align and std::aligned_storage for aligned allocation of memory blocks

I'm trying to allocate a block of memory of size size which needs to be Alignment aligned where the ... create an aligned_allocator this way? 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++ - Using ifstream to read floats

I'm trying to read a series of floats from a .out file using ifstream, but if I output them afterwards, ... 'm not getting the right output? 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++ - Perfect forwarding for void and non-void returning functions

Previously I was using a macro to measure the time a function call took whenever I wanted to quickly check that. Now, ... <Args>(args)...); } 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++ - read arguments from variadic template

I am a little confused about how can I read each argument from the tuple by using variadic templates. Consider ... the arguments in an array. 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++ - Ubuntu recognizes executable as shared library and won't run it by clicking

I am first experiencing this issue on my fresh installation of lubuntu 17.04. I have used to use Ubuntu before and ... :10: Elapsed time: 00:05 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::lockfree::spsc_queue busy wait strategy. Is there a blocking pop?

So i'm using a boost::lockfree::spec_queue to communicate via two boost_threads running functors of two objects in ... boost:: data structures? 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++ - Colorize sprites from grayscale to color

I have a lot of same graphics but different colors. I want to optimize it by colorizing from grayscale image. Also ... to: -> colorized to: 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 dynamically increase the array size?

I've been trying to make a program that adds 2 arrays of different size. But I would like to know to to dynamically ... [] a1.ptr; a1.ptr=ptr2; 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++ - smart pointers + "this" considered harmful?

In a C++ project that uses smart pointers, such as boost::shared_ptr, what is a good design philosophy ... prevent bugs related to this? See Question&Answers more detail:os...

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

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