Recent questions tagged C++

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c++ - How do I convert a char string to a wchar_t string?

I have a string in char* format and would like to convert it to wchar_t*, to pass to a Windows 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++ - does presence of mutex help getting rid of volatile key word ?

I have a multi-R/W lock class that keeps the read, write and pending read , pending write counters. A ... the optimizations. Regards, -Jay. 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 to use Move Constructors/Assignments

I've searched but cannot find the answer to "When" to use them. I just keep hearing that it's good because it ... is an array of bytes/pixels.) 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 `JNI_CreateJavaVM' linux

I'm trying to get familiar with the JNI API but can't get a sample c++ program to compile. Here is the ... oracle/jre/lib/amd64/server ./a.out 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 atomic_thread_fence(memory_order_seq_cst) have the semantics of a full memory barrier?

A full/general memory barrier is one where all the LOAD and STORE operations specified before the barrier will appear ... a full barrier has. 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 'enable_if' and 'is_same' with variadic function templates?

These two non-variadic function templates do compile: template <typename T, typename U> typename std:: ... for initializer list arguments. 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 do I have to use boost::asio:strand

Reading the document of boost::asio, it is still not clear when I need to use asio::strand. Suppose that I have ... I have to use asio::strand ? 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++ - changing probability of getting a random number

I would like to generate a random number between 0 and 3 and I have the following in my code: int ... algorithms to address this problem? 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++ - Double inheritance of enable_shared_from_this

I have an object (Z) which derives from two other objects (A and B). A and B both derive from ... I use the virtual trick too ? 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 declaration, scope and access control

Typically the 'using' declaration is used to bring into scope some member functions of base classes that would ... issue some kind of warning 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 only async-signal-safe functions be called from signal handlers safely?

I am still a little confused as to why exactly it is unsafe to receive a signal and call a non async ... to distinguish between the two calls. 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++ - Correct signature of / detect presence of Container::reserve()

Given a type C which is an STL-conforming container, how do I correctly detect if C contains a member ... requires a direct member 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++ - How is the memory layout of a class vs. a struct

I come from C programming where the data in a struct is laid out with the top variable first, then the ... in memory then the private variable? 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 the point-of-instantiation be delayed until the end of the translation unit?

Consider the following small code fragment: #include <iostream> template<class T> int test(); int main() { std ... end of the translation unit? 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 static_cast<Derived *>(Base pointer) give compile time error?

Should static_cast(Base pointer) give compile time error? class A { public: A() { } }; class B : public A { public ... >(a); // Compile Error? } 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++ - TNonblockingServer, TThreadedServer and TThreadPoolServer, which one fits best for my case?

Our analytic server is written in c++. It basically queries underlying storage engine and returns a fairly big ... fits my needs the best? 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++ - Listening to keyboard events without consuming them in X11 - Keyboard hooking

I tried to write a program which hooks keyboard messages to pronounce the name of each key whenever it is pressed in ... How can this be fixed? 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++ - unnamed namespace

What does it exactly mean when the Standard states $7.3.1.1/2 - "The use of the static keyword is ... names (e.g global static variables) 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++ - INT_[MIN|MAX] limit macros vs numeric_limits<T>

Is there any argument for using the numeric limits macros (e.g. INT64_MAX) over std::numeric_limits<T>? From ... C99 so therefore non-standard. 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++ - Operators overloading for enums

Is it possible to define operators for enums? For example I have enum Month in my class and I would like to be ... : ++my_month_; break; } } 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++ - Create shared_ptr to stack object

In my method a Player object is created like: Player player(fullName,age); My teacher gave us a piece of code ... new Player {fullName,age} }; 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 strong typedef as a more lightweight alternative to Boost Parameter library?

I often use the Boost strong typedef utility to improve the safety of my programs. For example by writing ... boost parameter library instead? 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++ - Configuring C++11 in Netbeans

I am using Netbeans 7.2, and I have downloaded GCC 4.7 using the Cygwin setup. I have also added the ... this specific to c++11 syntax? 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++ - Get index by type in std::variant

Is there a utility in the standard library to get the index of a given type in std::variant? Or should I make ... types on std::variant 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++ - How to expose std::vector<int> as a Python list using SWIG?

I'm trying to expose this function to Python using SWIG: std::vector<int> get_match_stats(); And I want ... will break strict-aliasing rules 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++ - Sorry, unimplemented: 64 bit mode not compiled in

This is what I'm trying to do(on Windows 7 64-bits): g++ -m64 -o main main.cpp And the error I get is: ... : win32? gcc version 4.9.3 <GCC> 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++ - Constructors : difference between defaulting and delegating a parameter

Today, I stumbled upon these standard declarations of std::vector constructors : // until C++14 explicit vector( ... second from the first ? 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++ - openCV imshow not rendering image on screen

I am new to openCV, have recently obtained a pre-compiled version of openCV 2.4.7 and was successfully ... help would be highly 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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