move-constructor Questions

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I've got the following implementation of the c++ concept move_constructible from cppreference template<typename _Tp> concept move_constructible = constructible_from<_Tp, _Tp> &&amp...
Beneath asked 22/11, 2021 at 4:40

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I want to refresh my memory on the conditions under which a compiler typically auto generates a default constructor, copy constructor and assignment operator. I recollect there were some rules, bu...

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I was working on some C++ code using std::move on shared_ptr and got really weird output. I've simplified my code as below int func(std::shared_ptr<int>&& a) { return 0; } int main(...

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I'm confused about when a move constructor gets called vs a copy constructor. I've read the following sources: Move constructor is not getting called in C++0x Move semantics and rvalue reference...
Manet asked 29/10, 2012 at 16:22

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As per this post, which says that[emphasise mine]: The move assignment operator is auto-generated if there is no user-declared copy constructor, copy assignment operator or destructor, and if the ...
Montserrat asked 4/5, 2022 at 3:54

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For move construction: After the move, other is guaranteed to be empty(). 1 For move assignment, the oft-quoted: other is in a valid but unspecified state afterwards. 2 Why is the state of othe...

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Synopsis How can I safely design a move constructor when a class uses multiple inheritance? Details Consider the following scenario: struct T { }; struct U { }; struct X : public T, public U {...

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Firstly, I really checked if there is a question already been asked but I could not find any. Error message should not deceive you my situation is a bit different I guess or I am just missing somet...

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Why does an explicitly defaulted destructor disable default move constructor in the class? I know that it does, as explained in several existing answers. (e.g. Explicitly defaulted destructor disab...
Saraband asked 2/12, 2021 at 22:3

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I'm working through Stroustrup's "Tour of C++ v2". It's certainly not a C++ beginner's book, but enjoyable. I've had a google and look through SO but no joy on this one. Now, I thought I ...
Northnorthwest asked 9/9, 2021 at 7:32

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Ok so I ran into a problem when implementing a c# property like system in c++ (see: https://mcmap.net/q/16573/-c-like-properties-in-native-c). Consider the following example: struct TransformCmp { ...
Phagy asked 28/7, 2021 at 11:46

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I'm using VS Code to compile and debug with g++ in Linux. Needed includes and usings: #include <string> #include <iostream> using namespace std; Here is my class which is moveab...
Hurtado asked 25/6, 2021 at 7:33

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I've recently learned about move constructors, but a lot of the online resources don't talk about copy elision. Copy elision makes sense to me too, but it left me wondering when is the move constru...
Caput asked 1/6, 2021 at 14:48

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Is there a better way to build a move constructor for a union-like class? If I were to have a union-like class like the class in the following code, is there a way to build the class or the move co...
Weinman asked 12/3, 2015 at 0:57

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It compiles with /permissive but fails with /permissive-. What is not conforming and how to fix it? Why it's fine in (2) but fails in (4)(3)? If I remove operator long it also fine. How to fix it...

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I am trying to understand the implementation of move-constructor. We all know if we need to manage resources in a C++ class, we need to implement Rule of five (C++ programming). Microsoft gives us...
Gesso asked 4/4, 2016 at 14:26

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Assume I have an object with both copy and move assignment operators defined. When I write this: Object a(/*parameters 1*/); /* some code */ a = Object(/*parameters 2*/); the third line will mos...
Annmarie asked 30/1, 2020 at 15:27

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According to the answer of this question, a default move constructor can be defined as noexcept under certain conditions. For instance, the following class generates a noexcept move constructor: c...
Cropeared asked 22/1, 2020 at 8:55

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What is the feature that allows me use auto for non-copyable (and non-movable) types in C++17 and didn't for C++14? Consider the following code: struct A{ A(A const&)=delete; A(A&&)...
Within asked 20/10, 2019 at 3:22

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Just came from is_assignable and std::unique_ptr. @Angew tells me that because std::unique_ptr<int, do_nothing> and std::unique_ptr<int> are different types, so static_assert(not std::i...
Cordierite asked 21/12, 2018 at 13:23

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I recently stumbled upon some strange behaviour (strange from my point of view) from move constructor. The result is different when compiling with GCC and Visual Studio. I would like to hear the ex...
Riyadh asked 15/12, 2018 at 15:14

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The MSDN article, How to: Write a Move Constuctor, has the following recommendation. If you provide both a move constructor and a move assignment operator for your class, you can eliminate redun...
Lowering asked 14/6, 2013 at 22:36

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The below code can be compiled successfully using Visual Studio 2015, but it failed using Visual Studio 2017. Visual Studio 2017 reports: error C2280: “std::pair::pair(const std::pair &)”: a...
Mullite asked 6/11, 2018 at 9:14

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Minimal working example. #include <cassert> #include <list> #include <queue> //#define USE_PQ struct MyClass { const char* str; MyClass(const char* _str) : str(_str) {} MyCla...
Mckeever asked 22/11, 2013 at 16:14

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In several places I've seen the recommended signatures of copy and move constructors given as: struct T { T(); T(const T& other); T(T&& other); }; Where the copy constructor takes...
Eclosion asked 26/5, 2012 at 22:11

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