Recent questions tagged C++

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c++ - Replacing PyString_FromString method in python 3

TLDR; PyString_FromString doesn't work in Python3.5 so I need an alternative. I am following an example for ... string to start with already. 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 I use a std::map with std::weak_ptr as key?

How can I use std::weak_ptr as key for a std::map as shown in the following code? #include <map> #include < ... class type and not an int.) 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 GCC's printf format attribute with C++11 variadic templates?

I have a C++ class that is the frontend for a logging system. Its logging function is implemented using C++11 ... C++11's variadic templates? 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++ - string and const char* and .c_str()?

I'm getting a weird problem and I want to know why it behaves like that. I have a class in ... between the two aforementioned methods? 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 an out-of-range enum conversion produce a value outside the underlying type?

Consider the following: #include <iostream> enum class E : bool { A, B }; void foo(E e) { switch(e) { ... if it were intended that it did. 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 required to explicitly list default parameters when using template template parameter?

I'd like to ask whether the following code sample should compile: #include <iostream> #include <vector> #include < ... this is not a duplicate. 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 unique_ptr's template arguments be deduced?

When you have class template argument deduction available from C++17, why can't you deduce the template ... a variable and variable template 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++ - sending/receiving a struct in boost::asio

I was going to send a struct from a client to a server using boost::asio::async_write_some, in this case ... other ideas please share them) 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 minimum spanning tree, how to do depth first?

I would like to construct a minimum spanning tree using the kruskal_minimum_spanning_tree algorithm available in the boost ... hint on 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++ exporting and using dll function

I can't quite figure out where there is a mistake. I am creating a DLL and then using it in a C ... be something really simple and fundamental. See Question&Answers more detail:os...

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

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166 views

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c++ - AST and operator precedence in rule definition

Hello [1] I have a simple parser (see below). It intends to parse conditional expressions (relational arithmetic ... [spirit-general] user list 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++ - Flickering on window when resizing from left side

It seems that my window is flickering whenever I move and window and resize at the same time. This usually occurs ... its origin X and Y. 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++ - "undefined reference" to a template class function

I am writing a template class for an array of objects, call it arrayobjclass, which holds pointers to other objects, ... true; } return false; } See Question&Answers more detail:os...

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

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359 views

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c++ - How to display a cv::Mat in a Windows Form application?

I tried to use imwrite to successfully to display an image on a Windows Form, but it damages the disk, so I ... . How do I accomplish 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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225 views

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c++ - Boost group_threads Maximal number of parallel thread

i want to apply boost group_thread in my program with a maximal number of Threads. For example int ... Thank you for your 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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2.6k views

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c++ - 'std::filesystem' has not been declared after including <experimental/filesystem>

I have checked a lot of issues about the link of filesystem under c++17 and I still cannot make the link successfully. ... : *** [all] Error 2 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++11 array initialization won't call copy constructor

I'm making a little class that uses an array templated on its size. Here's some code... .hpp template < ... .;@m64 Selected multilib: .;@m64 See Question&Answers more detail:os...

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

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207 views

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c++ - What is the scope of variables declared in a class constructor?

I was curious, what is the scope of variables declared inside a class constructor which are not data members of ... then global for the program? See Question&Answers more detail:os...

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

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140 views

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c++ - Value of int i = i ^ i ; Is it always zero or undefined behavior?

in following program, is output always zero, or undefined behavior? #include<iostream> int main() { int i= i ^ ... compiled, and output is 0. See Question&Answers more detail:os...

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

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157 views

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c++ - For each char in string gives wrong result

There's a string that is in UTF-8 encoding, I can read it from a file and write it into another ... n afternoon_gb_1 is u afternoon_gb_1 is n See Question&Answers more detail:os...

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

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512 views

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c++ - non-copyable objects and value initialization: g++ vs msvc

I'm seeing some different behavior between g++ and msvc around value initializing non-copyable objects. Consider ... with boost::noncopyable. See Question&Answers more detail:os...

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

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327 views

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c++ - Is it safe to serialize a raw boost::variant?

boost::variant claims that it is a value type. Does this mean that it's safe to simply write out the raw ... :variant be used in shared memory? See Question&Answers more detail:os...

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

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208 views

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c++ - Preventing multiple process instances on Linux

What is the best way on Linux platform for the process (C++ application) to check its instance is not already running? See Question&Answers more detail:os...

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

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298 views

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c++ - Explicit instantiation of function template using incomplete type

The following: template< typename > struct S; template< typename T > S< T >& f (S< T >& s) { ... dependent 'nested' well-formed. Any opinions? 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 access pixels data from ID3D11Texture2D?

I'm using Windows Desktop Duplication API to make my own mirroring protocol. I have this piece of code : // Get ... a RGB sequence ? 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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1.2k views

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c++ - Convert string from UTF-8 to ISO-8859-1

I'm trying to convert a UTF-8 string to a ISO-8859-1 char* for use in legacy code. The only way I'm ... if it is the only solution you know. See Question&Answers more detail:os...

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

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367 views

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c++ - Android NDK assert.h problems

First one - is what NDEBUG somehow already defined by default, so asserts don't work until you #undef it. Second ... i just do something 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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435 views

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c++ - Shared library on Linux and -fPIC error

I am trying to compile a shared library in Linux using a Makefile created with Cmake, but running make I obtain ... ? Thanks a lot in advance See Question&Answers more detail:os...

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

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