Recent questions tagged C++

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c++ - When should I prefer non-member non-friend functions to member functions?

Meyers mentioned in his book Effective C++ that in certain scenarios non-member non-friend functions are better ... when to use which? 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 wait until all child processes called by fork() complete?

I am forking a number of processes and I want to measure how long it takes to complete the whole task, that is when ... endl; } }//for }//main 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++ - Should I prefer Rcpp::NumericVector over std::vector?

Is there any reason why I should prefer Rcpp::NumericVector over std::vector<double>? For example, the two ... problems when interacting with R? 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 type of exception should I throw?

After going through some links on exception handling (1, 2, and 3), I know that C++ programs can ... way to implement such exceptions class. 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++ - SSE-copy, AVX-copy and std::copy performance

I'm tried to improve performance of copy operation via SSE and AVX: #include <immintrin.h> const int ... vectorization of copy operation? 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++ - warning: control reaches end of non-void function [-Wreturn-type]

I am having a slight is regarding functions. I believe it is likely because I am not using them. My code is ... it alone. Hope someone can help! 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 will happen if you do "delete this;" in a member function?

What will exactly happen if a member function try to do delete this;, like in the constructor of the following class? ... ~A() { delete pi; } 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++ - C++0x memory model and speculative loads/stores

So I was reading about the memory model that is part of the upcoming C++0x standard. However, I'm a bit confused ... 3.1.3 in N2197 as well. 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++ - Fast Arc Cos algorithm?

I have my own, very fast cos function: float sine(float x) { const float B = 4/pi; const float C = -4 ... fast way to calculate acos(x) Thanks. 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++ - Implementing a "variant" class

Note: I'm aware of boost::variant, but I am curious about the design principles. This question mostly ... <AbstractVariantImpl> mImpl; }; 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++ - Interoperability between boost::date_time and std::chrono

How interoperable are boost::date_time and std::chrono? For example, is there a way to convert between boost:: ... but couldn't find any. 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 obtain the index permutation after the sorting

Given an array arr = {5, 16, 4, 7}, we can sort it through sort(arr, arr+sizeof(arr)/sizeof(arr[0 ... can get the permutation index? Thank you 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 do I use Qt and SDL together?

I am building a physics simulation engine and editor in Windows. I want to build the editor part using Qt and ... since it uses SDL threads. 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++ - Saving to disk an in-memory database

I made a database through sqlite in c++. The db has been created in memory (using the ":memory:" parameter insted ... from c/c++ code). Greets. 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++ - inline function linker error

I am trying to use inline member functions of a particular class. For example the function declaration and ... these inline member functions)? 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++ - Debug Assertion Failed! Expression: _pFirstBlock == pHead

I am calling into a statically linked .dll, and I see this error: I wrote both the .dll and the calling ... nice solution, see the answer below. 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++ - Add/Remove data members with template parameters?

Consider the following code : template<bool AddMembers> class MyClass { public: void myFunction(); template< ... myVariable and addedVariable) ? 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 a call to 'this->template [somename]' do?

I've searched for this question and I can't find anything on it. Is there a better way to query something like ... Code and is not my own code. 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++ - Can/Should I inherit from an STL iterator?

Can/Should i inherit from STL iterator to implement my own iterator class? If no, why not? 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::any without RTTI, how does it work?

If I want to use std::any I can use it with RTTI switched off. The following example compiles and runs as ... code is nearly unreadable to me. 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 does Q_FOREACH (= foreach) macro work and why is it that complex?

In Qt, there is a foreach loop which is implemented using macros (Q_FOREACH). There are different implementations, ... a bit clearer for me! 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++ - When a compiler can infer a template parameter?

Sometimes it works sometimes not: template <class T> void f(T t) {} template <class T> class MyClass ... compiler can infer template parameter? 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 is an "operator int" function?

What is the "operator int" function below? What does it do? class INT { int a; public: INT(int ix = 0) { a = ix; ... ++(int) { return a++; } }; 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 explicit allowed for default constructors and constructors with 2 or more (non-default) parameters?

I understand that constructors with one (non-default) parameter act like implicit convertors, which convert from ... conversion of some sort? 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++ - Passing by value vs const & and && overloads

So after looking up move semantics I see that general consensus is to pass by value when you intend to ... simple pass by value function? 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 vectorization mean?

Is it a good idea to vectorize the code? What are good practices in terms of when to do it? What happens underneath? 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++ - Matlab Coder vs hand coding?

Some background for people reading this in the future (in case it's not locked). I tend to do my ... translation is there any other benefit? 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++ - Speeding up file I/O: mmap() vs. read()

I have a Linux application that reads 150-200 files (4-10GB) in parallel. Each file is read in turn in ... the discussions in mmap-vs-read. See Question&Answers more detail:os...

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

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