Recent questions tagged C++

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c++ - Do pthread mutexes work across threads if in shared memory?

I found this: Fast interprocess synchronization method I used to believe that a pthread mutex can only be shared between ... C++, on MacOSX. 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++ - Hash function for a string

We are currently dealing with hash function in my class. Our instructor asked us to a hash function on the ... my own efficient hash function. 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++ - Erase/Remove contents from the map (or any other STL container) while iterating it

Allegedly you cannot just erase/remove an element in a container while iterating as iterator becomes invalid. What ... or erase algorithm ? 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++ - Vary range of uniform_int_distribution

So i have a Random object: typedef unsigned int uint32; class Random { public: Random() = default; Random(std ... advice on other style issues) 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 writing to &str[0] buffer (of a std:string) well-defined behaviour in C++11?

char hello[] = "hello world"; std::string str; str.resize(sizeof(hello)-1); memcpy(&str[0], hello, sizeof(hello)-1 ... 98. Is it legal in C++11? 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++ - Fast divisibility tests (by 2,3,4,5,.., 16)?

What are the fastest divisibility tests? Say, given a little-endian architecture and a 32-bit signed integer: how to ... 2*2*...) k times 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++ - Do I have to use atomic<bool> for "exit" bool variable?

I need to set a flag for another thread to exit. That other thread checks the exit flag from time to time. Do I have ... exit = true; f.get(); } 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 member variables be used to initialize other members in an initialization list?

Consider the following (simplified) situation: class Foo { private: int evenA; int evenB; int evenSum; public: Foo ... . Thanks for your help! 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 check that the passed Iterator is a random access iterator?

I have the following code, which does some iterator arithmetic: template<class Iterator> void Foo(Iterator ... iterator meets this requirement? 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++ - Should I use cstdint?

I have been pondering on whether or not I should use the typedefs inside <cstdint> or not. I personally ... not? Are there any disadvantages? 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++ - Declaring type of pointers?

I just read that we need to give the type of pointers while declaring them in C (or C++) i.e.: int * ... why do we need to declare its type? 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++ - Convert char * to LPWSTR

I am trying to convert a program for multibyte character to Unicode. I have gone through the program and ... projects for several years now. 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++ - Vector Iterators Incompatible

I have a class with a std::vector data member e.g. class foo{ public: const std::vector<int> getVec() ... loop, I get the aforementioned error. 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 it possible to set an object to null?

Further in my code, I check to see check if an object is null/empty. Is there a way to set an object to null? 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 the 'type' of a lambda expression be expressed?

Thinking of lambda expressions as 'syntactic sugar' for callable objects, can the unnamed underlying type be expressed? An ... r; }) > s2; 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++ - Uses for anonymous namespaces in header files

Someone asserted on SO today that you should never use anonymous namespaces in header files. Normally this is correct, ... fill in the details? 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't std::ostream be moved?

Clearly, streams can't be copied. It should be possible to move streams. According to 27.9.1.11 [ofstream. ... std::ostream be moved itself? 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 const in vectors to allow adding elements, but not modifications to the already added?

My comments on this answer got me thinking about the issues of constness and sorting. I played around a bit and reduced ... = 1; // not allowed 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++ - Convert Eigen Matrix to C array

The Eigen library can map existing memory into Eigen matrices. float array[3]; Map<Vector3f>(array, 3).fill(10) ... stored as in normal c 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++ - C++11 std::to_string(double) - No trailing zeros

Today I tried out some new functions of the C++11 STL and encountered std::to_string. Lovely, lovely ... w/cpp/string/basic_string/to_string) 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 call memcpy() and memmove() with "number of bytes" set to zero?

Do I need to treat cases when I actully have nothing to move/copy with memmove()/memcpy() as edge cases ... in the former snippet necessary? 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++ - Compile OpenMP programs with gcc compiler on OS X Yosemite

$ gcc 12.c -fopenmp 12.c:9:9: fatal error: 'omp.h' file not found #include<omp.h> ^ 1 error generated ... So how do I compile programs with gcc? 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++ - Easiest way to make a cyclic iterator (circulator)?

I have an object that I want to travel in a continuous loop in a game. I have a series of coordinates in a std ... to write it in standard C++). 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 build Boost 1.64 in 64 bits?

I am running Windows 10 and have Visual Studio 2017 Community Edition installed in my laptop. I have some older ... wrong? Regards, Juan Dent 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++ - Creating a thread pool using boost

Is it possible to create a thread pool using boost's thread? i was looking all over boost's libs and I couldn't ... there a way to do it? tnx! 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 is better: reserve vector capacity, preallocate to size or push back in loop?

I have a function that takes a pointer to char array and segment size as input arguments and calls another function ... First post, big fan :) 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 load a custom binary resource in a VC++ static library as part of a dll?

I have custom binary resources (animated cursors) that would like to store as resources in a static lib in ... question are pretty cumbersome. 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 must std::sort compare function return false when arguments are equal?

In std::sort you can supply a third argument which is the basis for how it sorts a list. If you want ... when the compare function returns true. See Question&Answers more detail:os...

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

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