Recent questions tagged C++

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I have a code with multiple files, that uses the GSL Library. When I compile the code through the terminal ... find any answers online. 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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c++ - Why only std::atomic_flag is guaranteed to be lock-free?

From C++ Concurrency in Action: difference between std::atomic and std::atomic_flag is that std::atomic may not ... , is that the reason? 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 does subtracting X.begin() return the index of an iterator?

Having trouble understanding the below code: int data[5] = { 1, 5, 2, 4, 3 }; vector<int> X(data, ... returns the index of the max/min element? 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 shared_ptr has an explicit constructor

I was wondering why shared_ptr doesn't have an implicit constructor. The fact it doesn't is alluded to here: ... :shared_ptr<int>' requested */ 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 virtual keyword increase the size of derived a class?

I have two classes - one base class and one derived from it : class base { int i ; public : virtual ~ base ... 05, if someone really need this ) 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 indexing a new map element and having something that reads it assigned to it undefined behaviour, or just unspecified?

After answering this question, there was a long discussion over whether the code in question was undefined ... behavior and sequence points 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 does ~0 do?

Does ~0 mean its flipping 000000000 to 1111111111? printf("Check: %i", ~0); The printf results to -1 ... same thing as 11111111111111111 bits? 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++ - c++20 library support for xcode 12

can i use the c++20 library with xcode 12? (xcode 12 beta 5, with clang version 10.0.0). so in xcode ... c++20 library with xcode 12? 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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c++ - avx2 register bits reverse

Is there a (fast) way to perform bits reverse of 32bit int values within avx2 register ... representation of 1001011100101010011101101000101 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++ - IWebBrowser2: how to force links to open in new window?

The MSDN documentation on WebBrowser Customization explains how to prevent new windows from being opened and how ... . Replies 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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c++ - Why does this code crash at the places mentioned?

Can you please elaborate why this code crashes at the places mentioned? I am a bit stumped on this. I guess ... (derivedArray); return 0; } 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++ - automatic registration of object creator function with a macro

Basically, I want to automatically register object creator functions with an object factory for a bunch ... constructor DerivedD 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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c++ - How can I prevent my program from closing when a open console window is closed?

I am trying to open the console from my main program (Win32). I found some code, and it works, but I don't ... no idea of what I was reading. 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++ dynamic memory allocation using "new"

I'm new to C++, trying to learn by myself (I've got Java background). There's this concept of dynamic memory ... only copy it to a new array? 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++ - a problem with cl.exe and ml.exe

I used cl command to compile a cpp file: cl test.cpp //the generated test.exe can work well then I used ... to solve it? please help me. See Question&Answers more detail:os...

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

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262 views

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c++ - Is taking the address of a member of an uninitialized object well defined?

Consider the following example. When bar is constructed, it gives it's base type (foo) constructor the address of ... to back that up either. 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++ - Partial class template argument deduction in C++17

In the example below, we use the C++17 feature "Class template argument deduction" to deduce that val is of ... are there any good workarounds? 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++ - Function to check if string contains a number

I'm working on a project in c++ (which I just started learning) and can't understand why this function is not ... return false; } return true; } 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 winsock2 thread safe?

I am writing a small 3 servers and 1 client program. the 2 servers send tcp messages and the last one sends ... . Thank you for your help. 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++ - Comprehensive vector vs linked list benchmark for randomized insertions/deletions

So I am aware of this question, and others on SO that deal with issue, but most of those deal with the ... world performance" on some hardware. See Question&Answers more detail:os...

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

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487 views

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c++ - Intrinsic to count trailing zero bits in 64-bit integers?

this is sort of a follow up on some previous questions on bit manipulation. I modified the code from this ... do some inline assembler? 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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328 views

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c++ - If a global variable is initialized twice (statically, then dynamically), which initialization starts its lifetime?

Inspired by this question. We know that global variables with non-constexpr initializers undergo two different " ... be very weird. 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++ - Conversion between numeric types of the same kind

I was reading http://www.cplusplus.com/doc/tutorial/typecasting/. It says that: Otherwise, if the conversion is ... value? What is the reason? 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 dnorm with RcppArmadillo

From R, I'm trying to run sourceCpp on this file: #include <RcppArmadillo.h> // [[Rcpp::depends(RcppArmadillo)] ... dnorm above with R::dnorm4. 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 do I get a template error if I name my function `swap`, but `Swap` is okay?

Alright so heres the program and works absolutely right #include <iostream> using namespace std; template <typename T ... a capital letter ? 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++ - Enumerate members of a structure?

Is there a way to enumerate the members of a structure (struct | class) in C++ or C? I need to ... (pub_values) / sizeof(struct pub_values_t); See Question&Answers more detail:os...

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

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217 views

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c++ - How is "std::cin>>value" evaluated in a while loop?

Currently I'm self-learning C++ Primer 5th. Here comes something I'm not sure. (I couldn't find the exact ... it "returns its left operand". See Question&Answers more detail:os...

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

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380 views

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c++ - QApplication in unicode

QApplication's constructor takes an (int argc, char**argv) to handle any Qt specific commandline arguments. What ... that is itself unicode. See Question&Answers more detail:os...

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

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