Recent questions tagged C++

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c++ - Using unique_ptr to control a file descriptor

In theory, I should be able to use a custom pointer type and deleter in order to have unique_ptr manage an ... here that simply cannot be done? 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 can't a typedef of a function be used to define a function?

From § 8.3.5.11 of ISO/IEC 14882:2011(E): A typedef of function type may be used to ... potential expressive usefulness of function typedefs. 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++ - Python using ctypes to pass a char * array and populate results

I'm trying to use ctypes to create a char * array in python to be passed to a library for populating ... Any insight would be much 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++ - Pick a unique random subset from a set of unique values

C++. Visual Studio 2010. I have a std::vector V of N unique elements (heavy structs). How can ... std::random_shuffle for heavy objects? 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-callback to function template: explicitly instantiate template

Premise I'm using a C library (from C++) which provides the following interface: void register_callback(void* f, ... cast to make it compile) 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 index and query STL map containers by multiple keys?

I came across one requirement where the record is stored as Name : Employee_Id : Address where Name and ... function will look like. 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++ - Structured binding to replace std::tie abuse

In reading this summary of the c++17 final features I was a bit surprised by the section on structured bindings ... to above example as a hack? 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++ - debugging a process spawned with CreateProcess in Visual Studio

I've created a Windows/C++/WTL application that spawns a child process. The two processes communicate via ... Any insights greatly 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++ - Will C++0x support __stdcall or extern "C" capture-nothing lambdas?

Yesterday I was thinking about whether it would be possible to use the convenience of C++0x lambda functions ... lambdas can be compatible. 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 std::forward have two overloads?

Given the following reference collapsing rules T& & --> T& T&& & --> T& T& && --> T& T&& && --> T&& ... t really make sense in that case either. 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 integer to array

I would like to convert an integer into an array, so that it looks like the following: int number = 123456 ; int array[7 ... 2 ... array[6] = 6 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++ - If std::max() returns by reference (as it must), might that lead to a dangling reference?

Consider the paradigmatic max template function, std::max(): // From the STL // TEMPLATE FUNCTION _Debug_lt ... discussed in this question? 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 definitions outside class body

Is it O.K. to define virtual function of class template outside its body? Virtual function can not be inlined, ... Is it only gcc's behaviour? 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 `memset` function call be removed by compiler?

I have read here that compiler is free to remove call to memset if it knows that passed memory buffer is ... will have to investigate 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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c++ - Can virtual functions be constexpr?

Can virtual functions like X::f() in the following code struct X { constexpr virtual int f() const { return 0; } }; be constexpr? 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++ - "l-value required" error

When do we get "l-value required" error...while compiling C++ program???(i am using VC++ ) 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 protected inheritance cause dynamic_cast to fail?

I changed my C++ base class to be protected inheritance and my dynamic_cast(s) stopped working. Why should changing the ... < std::endl; } }; 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 send a set object in MPI_Send

I searched to send a set object and the closest I found was with vector (it's different and don't work ... Anyone can put a simple example? 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 read UTF-8 characters via a pointer?

Suppose I have UTF-8 content stored in memory, how do I read the characters using a pointer? I presume I need ... } ... return unicodeChar; } 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 use boost::filter_iterator for output?

I am using std::transform with an std::back_inserter to append elements to an std::deque. Now the ... filter_iterator as an output iterator? 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++ - Eigen boolean array slicing

In MATLAB it is common to slice out values that satisfy some condition from a matrix/array (called logical indexing). vec ... = vec.array() > 3; See Question&Answers more detail:os...

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

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137 views

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c++ - Reasons to not pass simple types by reference?

So far as I understand you should not pass simple types by reference in c++ because it does not improve perfomance ... variable or what is 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++ - Why doesn't printf format unicode parameters?

When using printf to format a double-byte string into a single-byte string: printf("%ls ", L"s:\яшертыHello"); ... way to make this not 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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256 views

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c++ - Cmake cannot find Boost libraries

I am new to Cmake and boost libraries in C++. I am working on a project that needs boost and Cmake. ... . Suggestions are most welcome. 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++ - Correctly over-loading a stringbuf to replace cout in a MATLAB mex file

MathWorks currently doesn't allow you to use cout from a mex file when the MATLAB desktop is open because they ... cout.rdbuf(mout.rdbuf()); 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 check if the binary representation of an integer is a palindrome?

How to check if the binary representation of an integer is a palindrome? See Question&Answers more detail:os...

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

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333 views

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c++ - Using commas inside a macro without parenthesis: How can I mix and match with a template?

Consider a simple macro: #define ECHO(x) x ECHO(foo(1, 2)) This produces the exact output we expect: foo(1, ... a template like this in a macro? 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++ - Check if class is a template specialization

I want to check if a class is a template specialization of another one. What I have tried is: template <class T, ... , class... Args> class foo; See Question&Answers more detail:os...

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

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