shared_ptr 亦可不占有对象,该情况下称它为空 (empty) (空 shared_ptr 可拥有非空存储指针,若以别名使用构造函数创建它)。 shared_ptr 的所有特化满足可复制构造 (CopyConstructible) 、可复制赋值 (CopyAssignable) 和可小于比较 (LessThanComparable) 的要求并可按语境转换为 bool 。 多个线程能在 shared_ptr ...
{ _GLIBCXX_THROW_OR_ABORT(bad_weak_ptr()); }using__gnu_cxx::_Lock_policy;using__gnu_cxx::__default_lock_policy;using__gnu_cxx::_S_single;using__gnu_cxx::_S_mutex;using__gnu_cxx::_S_atomic;//Empty helper class except when the template argument is _S_mutex.template<_Lock_polic...
to_be_deleted_(nullptr), threads_in_pop_(0) {}~LockFreeStack() {while(Pop()) {// Do nothing and wait for all elements are poped.}}LockFreeStack(constLockFreeStack& other) =delete;LockFreeStack&operator=(constLockFreeStack& other) =delete;boolIsEmpty()const{returnhead...
//Initialize with copy constructor. Increments ref count.autosp3(sp2);//Initialize via assignment. Increments ref count.autosp4 = sp2;//Initialize with nullptr. sp7 is empty.shared_ptr<Song> sp7(nullptr);// Initialize with another shared_ptr. sp1 and sp2// swap pointers as well as ref ...
no arguments: The resulting object is an emptyshared_ptrobject or an emptyweak_ptrobject. ptr: A pointer of typeOther*to the resource to be managed.Tmust be a complete type. If the function fails (because the control block can't be allocated), it evaluates the expressiondelete ptr. ...
If use_count returns zero, the shared pointer is empty and manages no objects (whether or not its stored pointer is nullptr). comparison with 1. If use_count returns 1, there are no other owners. The deprecated (since C++17) member function unique() is provided for this use case. (...
Return value the number of shared_ptr instances managing the current object or 0 if there is no managed object. Notes Common use cases include * comparison with 0. If use_count returns zero, the shared pointer is empty and manages no objects (whether or not its stored pointer is null). ...
LWG 2980C++11emptyshared_ptrs are never equivalentequivalent if they store the same pointer value See also atomic_is_lock_free (C++11) checks if the atomic type's operations are lock-free (function template) atomic_storeatomic_store_explicit ...
public member function <memory> std::shared_ptr::unique bool unique() const noexcept; Check if unique Returns whether theshared_ptrobject does not share ownership over its pointer with othershared_ptrobjects (i.e., it isunique). Empty pointers are neverunique(as they do not own any pointers...
#include<iostream>#include<memory>// for std::shared_ptr#include<string>classPerson{std::string m_name;std::shared_ptr<Person>m_partner;// initially created emptypublic:Person(conststd::string&name):m_name(name){std::cout<<m_name<<" created\n";}~Person(){std::cout<<m_name<<" d...