Recent questions tagged C++

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c++ - What's the difference between new char[10] and new char(10)

In C++, what's the difference between char *a = new char[10]; and char *a = new char(10); 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++ - Eigen how to concatenate matrix along a specific dimension?

I have two eigen matrices and I would like to concatenate them, like in matlab cat(0, A, B) Is there anything equivalent in eigen? 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++ - Idiomatic use of std::rel_ops

What is the preferred method of using std::rel_ops to add the full set of relational operators to a ... curious about the standard library. 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++ - Boolean values as 8 bit in compilers. Are operations on them inefficient?

I'm reading Agner Fog's "Optimizing software in C++" (specific to x86 processors for Intel, AMD and VIA) ... reference and then operate on 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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c++ - Is std::array movable?

Is std::array movable? In Bjarne Native 2012 presentation slides (slide 41) it lists std::array as one of the ... moved while std::vector can? 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 exactly is va_end for? Is it always necessary to call it?

va_end - Macro to reset arg_ptr. After accessing a variable argument list, the arg_ptr pointer is usually reset with ... : in your switch"? 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 isn't `std::initializer_list` defined as a literal type?

This is a follow-up of this question: Is it legal to declare a constexpr initializer_list object?. Since C++14 ... will get fixed in the future? 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 current working directory in a Qt application

I'm writing a program in C++ using the Qt library. There is a symbolic link in my home bin directory ... I find my current working directory? 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++ - Visual Studio: LINK : fatal error LNK1181: cannot open input file

I've been encountering a strange bug in Visual Studio 2010 for some time now. I have a solution consisting of a ... work. What is wrong 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++ - Symbol visibility and namespace

I'm experimenting with C++ symbol visibility on Linux and gcc. It seems that the preferred way is to ... is different to fvisibility=hidden? 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 execute two threads asynchronously using boost?

I have the book "beyond the C++ standard library" and there are no examples of multithreading using boost. ... boost- lets say asynchronously? 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++ - Reshaping a 1-d array to a multidimensional array

Taking into consideration the entire C++11 standard, is it possible for any conforming implementation to succeed the ... intermediate void *)? 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++ - strict aliasing and alignment

I need a safe way to alias between arbitrary POD types, conforming to ISO-C++11 explicitly considering 3.10/10 ... one modify this to be legal? 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 use of volatile keyword?

What is the use of volatile keyword in C/C++? What is the difference between declaring a variable volatile and not declaring it as volatile? 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 Allowed in a constexpr Function?

constexpr functions are not supposed to contain: A definition of a variable of non-literal type But in this ... to the div_t definition. 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 void* and to what variables/objects it can point to

Specifically, can it point to int/float etc.? What about objects like NSString and the like? Any examples will be greatly 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++ - Template tricks with const char* as a non-type parameter

I am very well aware that passing directly a const char* as a template non-type parameter is erroneous, since ... not the address of a variable 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++ - Global variable "count" ambiguous

#include <algorithm> using namespace std; int count = 0, cache[50]; int f(int n) { if(n == 2) count++; if ... for int 'cache[]'. Any reason why? 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 access a global variable within a local scope?

This is my code #include <iostream> using namespace std; int x = 5; int main() { int x = 1; cout << ... the global x variable. 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++ - How can I quickly enumerate directories on Win32?

I'm trying to speedup directory enumeration in C++, where I'm recursing into subdirectories. I currently ... accomplish something like 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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c++ - Can we get the type of a lambda argument?

Using std::function, we can get the type of an argument using the argument_type, second_argument_type etc. typedefs, but ... . C'est la vie! 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++ - Intel AVX: 256-bits version of dot product for double precision floating point variables

The Intel Advanced Vector Extensions (AVX) offers no dot product in the 256-bit version (YMM register) for ... give hints for the suggestions? 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++ - SFINAE and partial class template specializations

I have been using SFINAE-based approaches for quite some time, especially to enable/disable specific class template ... really a grey area? 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 test if a constexpr function is evaluated at compile time?

Since the extended versions of constexpr (I think from C++14) you can declare constexpr functions that could ... was evaluated at compile time? 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 functions be used to initialize member variables in an initialization list?

OK, member variables can be used to initialize other member variables in an initialization list (with care taken about ... // other stuff }; 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++ - Implementation of operators for enum class

Following the discussion in question Incrementation and decrementation of enum class , I'd like to ask about ... docs/papers/2016/p0138r2.pdf See Question&Answers more detail:os...

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

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286 views

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c++ - Convert a quadratic bezier to a cubic one

What is the algorithm to convert a quadratic bezier (with 3 points) to a cubic one (with 4 points)? 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 lambdas: member variable capture gotcha

Consider this code: #include <memory> #include <iostream> class A { public: A(int data) : data_(data) { ... it's something entirely different? See Question&Answers more detail:os...

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

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