Recent questions tagged C++

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c++ - Should implicitly generated assignment operators be & ref-qualified?

The following code compiles without problem on gcc 4.8.1: #include <utility> struct foo { }; int main() { foo bar; ... operator=( foo && ) &; }; 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++ - specializing iterator_traits

I'd like to specialize std::iterator_traits<> for iterators of a container class template that does not have the ... instances of Container<T>. 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 improve fixed point square-root for small values

I am using Anthony Williams' fixed point library described in the Dr Dobb's article "Optimizing Math-Intensive ... square of the limit! 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 the move constructor of ifsteam implicitly deleted?

I have the following simple class: class Source { public: Source() = default; Source(Source const&) = delete; Source( ... 4.7.2 has a bug? 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++ - Algorithm for dividing very large numbers

I need to write an algorithm(I cannot use any 3rd party library, because this is an assignment) to divide( ... 5 until reaching to the end 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 compiler sometimes cache variable declared as volatile

From what I know, the compiler never optimizes a variable that is declared as volatile. However, I have an array ... 't see the modified value. 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++ - Structure of arrays and array of structures - performance difference

I have a class like this: //Array of Structures class Unit { public: float v; float u; //And ... static and dynamically allocated memory? 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++ - Removing widgets from QGridLayout

I try to remove widgets from a specified row in a QGridLayout like this: void delete_grid_row(QGridLayout *layout ... iteration. Any ideas? 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++ - Avoiding extra move in make_unique/make_shared/emplace/etc for structures that use aggregate initialization

std::make_unique() (and similar functions) have a little problem: #include <cstdio> #include <memory> using ... factory. See details here. 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 stop Windows from blocking the program during a window drag or menu button being held down?

I am novice with Win32, and I have been pursuing a problem (if it can be called a problem at all) with ... is still hard for me to interpret. See Question&Answers more detail:os...

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

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192 views

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c++ - Find the subsequence with largest sum of elements in an array

I recently interviewed with a company and they asked me to write an algorithm that finds the subsequence with ... are very much 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++ - class template instantiation

I just read the wiki article about CRTP, and I'm a little confused about template instantiation. According to the ... in question 1, right? } 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 the rule that allows `this->` to access members of dependent base classes?

As we know, the code below is ill-formed because the member x is in a dependent base class. However, ... specifies the "correct" behaviour? See Question&Answers more detail:os...

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

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265 views

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c++ - Xlib How Does This (Removing Window Decoration) Work?

How does the following code remove window borders? //note the struct is declared elsewhere, is here just for ... Thanks in advance, ell. See Question&Answers more detail:os...

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

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316 views

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c++ - how do i prevent screen-savers and sleeps during my program execution?

In a c++ program run on Win7, is there a way to fake a mouse movement or something like that, just to keep ... not to use .NET. Thanks, -nuun See Question&Answers more detail:os...

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

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83 views

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c++ - Cost of using std::map with std::string keys vs int keys?

I know that the individual map queries take a maximum of log(N) time. However I was wondering, I have seen a ... <int, aClass*> someMap; 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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264 views

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c++ - uint8_t iostream behavior

Abstract: I was expecting the code: cout << uint8_t(0); to print "0", but it doesn't print anything. Long version: When ... ,f}) { print(i); } } See Question&Answers more detail:os...

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

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116 views

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c++ - Why does my program run way faster when I enable profiling?

I have a program that's running pretty slowly (takes like 20 seconds even on release) so, wanting to fix it, I ... I have a memory leak :-/ See Question&Answers more detail:os...

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

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147 views

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c++ - std::bind vs lambda performance

I wanted to time a few functions' execution and I've written myself a helper: using namespace std; template<int ... . How would you explain it? See Question&Answers more detail:os...

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

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218 views

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c++ - LNK2022 metadata operation: Inconsistent layout information in duplicated types

I'm having a new-to-me linker error in a project I'm working with: 1>MSVCMRTD.lib(locale0_implib.obj) : ... size or something... Any ideas? See Question&Answers more detail:os...

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

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187 views

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c++ - Accessing same-type inactive member in unions

I have something like this: union DataXYZ { struct complex_t { float real, imag; } complex; struct vector_t { ... yet - hence this 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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394 views

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c++ - Create va_list dynamically

I have a function void foo(int cnt, va_list ap); I need to use it, but requirement is quite strict, number ... clue about how I could do this? See Question&Answers more detail:os...

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

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192 views

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c++ - Linking not working in homebrew's cmake since Mojave

I've reproduced this symptom on two computers now, cmake seems to no longer look in /usr/local/lib (or ... and the Apple developer forums. 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++ - boost::asio UDP broadcasting

I want to broadcast UDP messages to all computers in a local network using boost::asio. Working through the examples ... What am I doing wrong? See Question&Answers more detail:os...

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

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215 views

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c++ - Check whether iterator belongs to a list

Is there any way to check whether a given iterator belongs to a given list in 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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110 views

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c++ - calling operator<< in gdb

How do you call operator<<(std::ostream &os, const ClassX &x) from inside gdb ? In other words, how do you print ... to work for me! Any ideas? See Question&Answers more detail:os...

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

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375 views

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c++ - Why is the std::accumulate function showing the wrong sum of a vector<double>?

Consider the following code for adding all the elements of a vector: #include<iostream> #include<algorithm> #include< ... a vector of doubles? See Question&Answers more detail:os...

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

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227 views

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c++ - Constructor with by-value parameter & noexcept

In this example code: explicit MyClass(std::wstring text) noexcept; Is the use of noexcept here correct? ... taking a by-value parameter. See Question&Answers more detail:os...

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

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