Recent questions tagged C++

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c++ - Virtual dispatch implementation details

First of all, I want to make myself clear that I do understand that there is no notion of vtables and vptrs in ... B and C) Thanks in advance. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to pass and execute anonymous function as parameter in C++11?

The code I'm looking for is like following. bool Func1(int Arg1, C++11LambdaFunc Arg2){ if(Arg1 > 0){ return Arg2(Arg1) ... ) -> bool { ... } ); See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - What's the best hashing algorithm to use on a stl string when using hash_map?

I've found the standard hashing function on VS2005 is painfully slow when trying to achieve high performance ... should void most collisions? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How do I encode a string to base64 using only boost?

I'm trying to quickly encode a simple ASCII string to base64 (Basic HTTP Authentication using boost::asio) ... algorithm explicitly to my code? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Get list of static libraries used in an executable

Since ldd lists only the dynamic libraries, is there a way to extract the information about the static libraries used to create the executable? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - When to use std::async vs std::threads?

Can anybody give a high level intuition about when to use each of them? References: Is it smart to replace ... the other std::thread mechanisms? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Exclude source file in compilation using Makefile

Is it possible to exclude a source file in the compilation process using wildcard function in a Makefile? Like have ... .cpp. Is this possible? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - If a 32-bit integer overflows, can we use a 40-bit structure instead of a 64-bit long one?

If, say, a 32-bit integer is overflowing, instead of upgrading int to long, can we make use of some 40- ... and space is a bigger constraint. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Current date and time as string

I wrote a function to get a current date and time in format: DD-MM-YYYY HH:MM:SS. It works but let's ... dateString += tmp; return dateString; } See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - operator << must take exactly one argument

a.h #include "logic.h" ... class A { friend ostream& operator<<(ostream&, A&); ... }; logic.cpp #include ... one argument. What is the problem? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Is "long long" = "long long int" = "long int long" = "int long long"?

I found both long int long and int long long can compile for a variable type. Is there any difference between ... lilp; long long int* llip; See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Template class with template container

How can I declare template class (adaptor) with different containers as template arguments? For example, I ... template argument to container. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Why emplace_back is faster than push_back?

I thought that emplace_back would be the winner, when doing something like this: v.push_back(myClass(arg1, arg2)); ... the code in release mode. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - What's the difference between sockaddr, sockaddr_in, and sockaddr_in6?

I know that sockaddr_in is for IPv4, and sockaddr_in6 for IPv6. The confusion to me is the difference between sockaddr ... , sizeof(ipStr)); } See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Parallel for vs omp simd: when to use each?

OpenMP 4.0 introduces a new construct called "omp simd". What is the benefit of using this construct over ... related to the SIMD directive. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Can I use Qt without qmake or Qt Creator?

I want to program using Qt, but I don't want to use special compilers or IDE such as Qt Creator and qmake. I want ... do I compile it with g++? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Multiple classes in a header file vs. a single header file per class

For whatever reason, our company has a coding guideline that states: Each class shall have it's own header and ... .4 as our everyday compiler] See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - error: ‘NULL’ was not declared in this scope

I get this message when compiling C++ on gcc 4.3 error: NULL' was not declared in this scope It appears and ... don't know why. Why? Thanks. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Locking strategies and techniques for preventing deadlocks in code

The common solution to preventing deadlock in code is to make sure the sequence of locking occur in a ... guarantee dead lock prevention? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - C++11 styled callbacks?

I have a void function inside of a class. In old C++ i'd make a function static ... creating callbacks to myclassVar.voidReturnVoidParamFunc See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Modifying vertex properties in a Boost::Graph

I am trying to figure out how to use boost::graph to store some information. However, there is information I ... for a simple example use. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - C++11 memory pool design pattern?

I have a program that contains a processing phase that needs to use a bunch of different object instances (all ... so is there a workaround? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Function pointer as parameter

I try to call a function which passed as function pointer with no argument, but I can't make it work. ... *disconnectFunc; connected = false; } See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - C++11: why does std::condition_variable use std::unique_lock?

I am a bit confused about the role of std::unique_lock when working with std::condition_variable. As far as I ... , how exactly is it faster? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Why can a T* be passed in register, but a unique_ptr<T> cannot?

I'm watching Chandler Carruth's talk in CppCon 2019: There are no Zero-Cost Abstractions in it, he gives the example ... baz(std::move(ptr)); } See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Memory model ordering and visibility?

I tried looking for details on this, I even read the standard on mutexes and atomics... but still I couldnt ... /1234-random idx in array } See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How does Intel TBB's scalable_allocator work?

What does the tbb::scalable_allocator in Intel Threading Building Blocks actually do under the hood ? It can certainly ... 3.0 from testing). See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Difference between steady_clock vs system_clock?

I am trying to see whether my data is 120 second old or not by looking at the timestamp of the data so I have ... this code on Ubuntu 14.04 box. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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