Recent questions tagged C++

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c++ - Is it safe to "upcast" a method pointer and use it with base class pointer?

Let's say I have a pointer type that can hold the address of a base class method. Can I assign the ... the situation in my example 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++ - Why would connect() give EADDRNOTAVAIL?

I have in my application a failure that arose which does not seem to be reproducible. I have a TCP socket ... try to recover from this failure? 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++ - unique_ptr, pimpl/forward declaration and complete definition

I already checked out the questions here and here, but still cannot figure out what is wrong. This is the calling ... else am I missing 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++ - Why does std::fstream set the EOF bit the way it does?

I recently ran into a problem caused by using fstream::eof(). I read the following line from here: The function eof( ... would I use eof() for? 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++ - Constructor and copy-constructor for class containing union with non-trivial members

I am trying to implement a custom variant type which uses a union to store data of various different ... constructor and copy constructor? See Question&Answers more detail:os...

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

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390 views

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c++ - Can I remove elements from std::list, when I'm iterating on it?

Can I remove elements from std::list, when I'm iterating on it? For example so: std::list<int> lst; //.... ... lst.remove(*itr); } ? And why? 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 the equivalent of boost::make_transform_iterator in the standard library?

When dealing with a const vector, the following doesn't work: const std::vector<std::string> v; v.push_back ... library doesn't have 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++ - Does the alignas specifier work with 'new'?

My question is rather simple; Does the alignas specifier work with 'new'? That is, if a struct is defined ... aligned when allocated with new? 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++ - Replace giant switch statement with what?

I have a code that parses some template files and when it finds a placeholder, it replaces it with a value. ... . Should I care about 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++ - Detect if a type is a std::tuple?

Currently I have two functions : template<typename Type> bool f(Type* x); template<typename... List> bool f(std::tuple< ... */> bool f(Type* x); See Question&Answers more detail:os...

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

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769 views

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c++ - Fast controlled copy from istream to ostream

I have to copy several bytes from a istream to a ostream, there are 2 ways that I know to perform this copy. ... to a given number of bytes? 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's the difference between declaring functions before or after main()?

What's the difference between: void function(); int main() {......} void function() {......} ... writes functions like the first 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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443 views

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c++ - Get a font filename based on Font Name and Style (Bold/Italic)

This has been driving me crazy all day. I need to get a font filename (eg. Arial.ttf) based on its name ( ... could achieve this in C++ (Win32) See Question&Answers more detail:os...

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

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257 views

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c++ - Why does std::result_of take an (unrelated) function type as a type argument?

I realize "why are things the way they are" questions are not usually the best, but there are many people ... of decltype fairly easily anyway? See Question&Answers more detail:os...

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

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294 views

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c++ - Visual Studio 2015 C# XAML Designer doesn't load

In the new Visual Studio 2015 RC the XAML designer does not bring up a UI for a C# Windows Universal ... and have a workaround/solution? See Question&Answers more detail:os...

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

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458 views

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c++ - Fast sparse matrix multiplication

for class I have to write my own linear equation solver for sparse matrices. I am free to use any type ... with another data structure? 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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542 views

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c++ - What is the reason for `std::result_of` deprecated in C++17?

I saw std::result_of is being deprecated in C++17. What is the reason for std::result_of deprecated in C ... ::result_of and std::invoke_result. See Question&Answers more detail:os...

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

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179 views

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c++ - Legal definitions of main() in C++14

The last draft of C++14 that I was able to find says, regarding main() [3.6.1]: An implementation shall not ... return 0; } auto 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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375 views

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c++ - C++11 vector<bool> performance issue (with code example)

I notice that vector is much slower than bool array when running the following code. int main() { int count ... than std::vector::assign. See Question&Answers more detail:os...

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

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210 views

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c++ - Will std::string end up being our compile-time string after all?

Many developers and library authors have been struggling with compile-time strings for quite a few years now - as the ... to be std::string. See Question&Answers more detail:os...

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

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303 views

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c++ - How do I invoke the MinGW cross-compiler on Linux?

I have a project that I want to cross-compile for Windows. I have the appropriate Makefile and everything works ... I actually compile with 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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318 views

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c++ - How can I detect the last iteration in a loop over std::map?

I'm trying to figure out the best way to determine whether I'm in the last iteration of a loop over a ... no random access iterators for maps! See Question&Answers more detail:os...

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

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390 views

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c++ - Why aren't static data members allowed in local classes?

What is the reasoning to why static const members cannot exist in local classes? It seems like a rather silly ... not have static data members. 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 I determine the number of channels in cv::Mat Opencv

This maybe rudimentary, but is it possible to know how many channels a cv::Mat has? For eg, we load an RGB ... help me here. Thanks 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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c++ - Container of fixed dynamic size

Is there a standard container for a sequence of fixed length, where that length is determined at runtime. Preferrably, ... ctor_args2.end()); } See Question&Answers more detail:os...

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

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283 views

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c++ - Unable to get hudson to parse JUnit test output XML

EDIT: This issue has been fixed by google in gtest 1.4.0; see the original bug report for more information. ... point me in the right direction? See Question&Answers more detail:os...

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

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232 views

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c++ - How to run Cmake in Visual Studio Code using tasks

I'm trying to run cmake with ctrl+shift+B like so: { "version": "2.0.0", "tasks": [ { "label" ... cwd variable in the options item should 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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273 views

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c++ - A clean way to store a function and its (arbitrary-type, arbitrary-number) arguments

For a library, I'd like a function to accept another function and its arguments, then store them all for calling ... method I'd like to add. See Question&Answers more detail:os...

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

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