Recent questions tagged C++

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c++ - Why does std::array not have an constructor that takes a value for the array to be filled with?

Is the absence of std::array<T,size>::array(const T& value); an oversight? It seems mighty useful to me, and ... want all -1's like this guy? 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 pass std::string to a DLL?

I separated a code fragment into a DLL because it will be frequently updated and in this way it should be easier ... or a Cstring? 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++ - How to set baud rate to 307200 on Linux?

Basically I'm using the following code to set the baud rate of a serial port: struct termios options; tcgetattr( ... just reports it as 16550A. 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++ - Acquire/release semantics with non-temporal stores on x64

I have something like: if (f = acquire_load() == ) { ... use Foo } and: auto f = new Foo(); ... as long as there's a compiler barrier. 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 class functions/variables have to be declared before being used?

So I was learning about classes and I stumbled upon something I found was quite awkward to me. class Nebla { public ... , I get an error? 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++ - Why is memset() incorrectly initializing int?

Why is the output of the following program 84215045? int grid[110]; int main() { memset(grid, 5, 100 * sizeof(int)) ... ", grid[0]); return 0; } 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 are by-value parameters excluded from NRVO?

Imagine: S f(S a) { return a; } Why is it not allowed to alias a and the return value slot? S s = f ... of move/copy constructor). Why is that? 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 tell if the c function atoi failed or if it was a string of zeros?

When using the function atoi (or strtol or similar functions for that matter), how can you tell if the ... may also have leading whitespace. 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++ - Unresolved external symbol LNK2019

First of all, I know this question is all over this site but I have looked at almost all of them and can't seem to ... , 0 skipped ========== 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++ - Are int8_t and uint8_t intended to be char types?

Given this C++11 program, should I expect to see a number or a letter? Or not make expectations? #include < ... or will be a character 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++ - Identifier not found error on function call

I have a program here where I invert the case of an entered string. This is the code in my .cpp file ... for syntax or semantics is appreciated. 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++ - Cancelling boost asio deadline timer safely

I'm trying to cancel a boost::asio::basic_waitable_timer<std::chrono::steady_clock> safely. According to this ... . Main waits forever. 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 does this variadic template code do?

template <class F, class... Args> void for_each_argument(F f, Args&&... args) { [](...){}((f ... featured on isocpp.org without explanation. 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++ - Initialisation and assignment

What EXACTLY is the difference between INITIALIZATION and ASSIGNMENT ? PS : If possible please give examples in ... doing implicit assignments. 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 initialize std::vector over already allocated memory?

My question is fairly simple and I am quite surprised I can't find anything related. Probably it is easy or ... needs to be able to reallocate. See Question&Answers more detail:os...

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

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278 views

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c++ - dereferencing the null pointer

int* p = 0; int* q = &*p; Is this undefined behavior or not? I browsed some related questions, but this specific aspect didn't show up. 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++ - Create an Application without a Window

How would you program a C/C++ application that could run without opening a window or console? 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++ - overloading base class method in derived class

I am trying to understand why the following code does not compile, apparently the solution relies in specifically ... behaves in this case. See Question&Answers more detail:os...

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

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240 views

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c++ - Find all a substring's occurrences and locations

I'm writing a program to parse some data saved as text files. What I am trying to do is find the location ... looking to find the index also. 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++ - Multi-dimensional vector

How can I create a 2D vector? I know that in 2D array, I can express it like: a[0][1]=98; a[0][2]=95 ... one do this using the C++ STL Vector? 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 can I get rid of the __imp__ prefix in the linker in VC++?

I'm using libcurl and am getting the following sort of linker errors in VC++ 10. 1>main.obj : error LNK2019: ... the right lib, right path etc. 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 print __int128 in g++?

I am using the GCC built-in type __int128 for a few things in my C++ program, nothing really significant, at least ... C++ as I am asking 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++ - Error: variable "cannot be implicitly captured because no default capture mode has been specified"

I am trying to follow this example to use a lambda with remove_if. Here is my attempt: int flagId = ... flagId, in the lambda expression? 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 create the Cartesian product of a type list?

I'd like to create the cross product of a list of types using variadic templates. Here's what I have ... unwrap" the nested type_lists somehow? 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++ - SDL2: Fast Pixel Manipulation

I want to draw pixels on the monitor which change frequently after certain parameters. E.G. if a Red and Green ... Pixels in a fast manner? See Question&Answers more detail:os...

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

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306 views

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c++ - Copy constructor of template class

I read that template copy-con is never default copy onstructor, and template assignment-op is never a copy ... of template class. 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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262 views

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c++ - CUDA how to get grid, block, thread size and parallalize non square matrix calculation

I am new to CUDA and need help understanding some things. I need help parallelizing these two for loops. ... going and use them effectively. 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++ - Inferring the call signature of a lambda or arbitrary callable for "make_function"

In some situations it's desirable to be able to type-erase a callable (e.g. function, function pointer, ... Edit: answering my own question. See Question&Answers more detail:os...

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

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