structX{X(X&&other);// move constructor// X(X other); // Error: incorrect parameter type};unionY{Y(Y&&other,intnum=1);// move constructor with multiple parameters// Y(Y&& other, int num); // Error: `num` has no default argument}; ...
将Lvalue -> Rvalue ,进而调用参数为右值类型的函数,如move ctor / move assgin 函数参数为const左值引用&意味着拷贝,为右值引用&&意味着移动。 TestCase #include<iostream> #include<string> using namespace std; class Apple { public: Apple() { val = 1; std::cout << " Apple default ctor" <<...
(D&&)=default;// 强制生成移动构造函数};intmain(){std::cout<<"尝试移动 A\n";A a1=f(A());// 按值返回时,从函数形参移动构造它的目标std::cout<<"移动前,a1.s = "<<std::quoted(a1.s)<<" a1.k = "<<a1.k<<'\n';A a2=std::move(a1);// 从亡值移动构造std::cout<<"...
测试代码如下: #include<iostream>usingnamespacestd;// 对构造函数进行explicit修饰classExplicitClass{public:ExplicitClass(){cout<<"Default construction"<<endl;data=nullptr;}explicitExplicitClass(inta){cout<<"Single-parameter construction"<<endl;data=newint(a);}explicitExplicitClass(constExplicitClass&rhs)...
#include <string> #include <type_traits> struct S1 { std::string str; // member has a non-trivial default constructor }; static_assert(std::is_default_constructible_v<S1> == true); static_assert(std::is_trivially_default_constructible_v<S1> == false); struct S2 { int n; S2() =...
move constructor does not match the calculated one Foo(Foo&&) noexcept = default; // won't help ^ yaml3.cpp:8:10: error: exception specification of explicitly defaulted move assignment operator does not match the calculated one Foo& operator=(Foo&&) noexcept = default; // won't help ^ ...
only inherit from the direct base class. default, copy and move constructors can not inherit. any data members of its own are default initialized. the rest details are in the section section 15.7.4.Bulk_quoteExercise 15.28Exercise 15.29:Repeat your program, but this time store shared_ptrs to...
— has no non-trivial move assignment operators (13.5.3, 12.8), and — has a trivial destructor (12.4).A trivial class is a class that has a trivial default constructor (12.1) and is trivially copyable.[Note: In particular, a trivially copyable or trivial class does not have virtual fu...
struct move_only_type { move_only_type() = delete; move_only_type(int ii): i(ii) {} move_only_type(const move_only_type&) = delete; move_only_type(move_only_type&&) = default; int i; }; namespace nlohmann { template <> struct adl_serializer<move_only_type> { // note: the...
在C++11中增加了move操作,如果需要某个类支持移动操作,那么需要实现移动构造和移动赋值操作符。移动构造函数和移动赋值操作符都是具有移动语义的,应该同时出现或者禁止。// 同时出现 class Foo { public: ... Foo(Foo&&); Foo& operator=(Foo&&); ... }; // 同时default, C++11支持 class Foo { publi...