在自定义分配器中,一般不需要手动实现construct和destroy,因为标准库中的std::allocator_traits会处理这些工作。std::allocator_traits默认会使用placement new来调用对象的构造函数,并调用对象的析构函数。 相当于在CustomAllocator中增加以下函数: template<typenameU,typename...
template <typename T> class CustomAllocator { public: using value_type = T; using size_type = std::size_t; using difference_type = std::ptrdiff_t; CustomAllocator() = default; ~CustomAllocator() = default; template <typename U> CustomAllocator(const CustomAllocator<U>&) noexcept {} T*...
分配器(allocator):用于分配和释放控制块和对象的内存的分配器,通常是 std::allocator。 引用计数(Reference Counting) 当我们创建一个 std::shared_ptr,它会初始化引用计数为1,并创建一个控制块。当我们复制或赋值一个 shared_ptr,它会指向同一个对象,并增加该对象控制块中的引用计数。当 shared_ptr 的实例被...
std::shared_ptr<int> p4 (newint, std::default_delete<int>()); std::shared_ptr<int> p5 (newint, [](int* p){delete p;}, std::allocator<int>()); std::shared_ptr<int>p6 (p5); std::shared_ptr<int>p7 (std::move(p6)); std::shared_ptr<int> p8 (std::unique_ptr<int>(n...
* the allocator (type-erased); * the number of shared_ptrs that own the managed object; * the number of weak_ptrs that refer to the managed object. When shared_ptr is created by calling std::make_shared or std::allocate_shared, the memory for both the control block and the managed ...
问如何重新循环为std::shared_ptr分配的控制块EN多个shared_ptr管理同一个指针，仅当最后一个shared_ptr...
the allocator (type-erased); the number of shared_ptrs that own the managed object; the number of weak_ptrs that refer to the managed object. When shared_ptr is created by calling std::make_shared or std::allocate_shared, the memory for both the control block and the managed object...
引用计数指的是，所有管理同一个裸指针（raw pointer）的shared_ptr，都共享一个引用计数器，每当一个...
creates a shared pointer that manages a new object allocated using an allocator (function template) static_pointer_cast dynamic_pointer_cast const_pointer_cast appliesstatic_castdynamic_cast (function template) get_deleter returns the deleter of specified type, if owned ...
alloc-an allocator to use for allocations of data for internal use r-another smart pointer to share the ownership to or acquire the ownership from Postconditions 1,2)use_count()equals0andget()equalsnullptr. 3-7)use_count()equals1andget()equalsptr. ...