Section 3: library functions
std::any::operator= – std::any::operator= Synopsis any &operator=(const any &rhs); (1)(since C++ 17) any & operator=(any &&rhs) noexcept; (2)(since C++ 17) template <typename ValueType> (3)(since C++ 17) any & operator=(ValueType &&rhs); Assigns contents to the contained value. 1) Assigns by copying the state of rhs, as if by any(rhs).swap(*this). 2) Assigns by moving the state of rhs,…
std::any::has_value – std::any::has_value Synopsis bool has_value() const noexcept; (since C++17) Checks whether the object contains a value. Parameters (none) Return value true if instance contains a value, otherwise false.
std::any::emplace – std::any::emplace Synopsis template< class ValueType, class… Args > (1) (since C++17) std::decay_t<ValueType>& emplace( Args&&… args ); template< class ValueType, class U, class… Args > (2) (since C++17) std::decay_t<ValueType>& emplace( std::initializer_list<U> il, Args&&… args ); Changes the contained object to one of type std::decay_t<ValueType> constructed from the arguments. First destroys the current contained object…
std::any::~any – std::any::~any Synopsis ~any(); (since C++17) Destroys the contained object, if any, as if by a call to reset(). See also destroys contained object reset (public member function)
std::any – std::any Synopsis Defined in header <any> class any; (since C++17) The class any describes a type-safe container for single values of any type. 1) An object of class any stores an instance of any type that satisfies the constructor requirements or is empty, and this is referred to as the state of the…
std::allocator_traits<Alloc>::select_on_container_copy_construction – std::allocator_traits<Alloc>::select_on_container_copy_construction Synopsis Defined in header <memory> static Alloc select_on_container_copy_construction( const Alloc& a ); (since C++11) If possible, obtains the copy-constructed version of the allocator a, by calling a.select_on_container_copy_construction(). If the above is not possible (e.g. a does not have the member function select_on_container_copy_construction(), then returns a, unmodified. This function is called by the…
std::allocator_traits<Alloc>::max_size – std::allocator_traits<Alloc>::max_size Synopsis Defined in header <memory> static size_type max_size( const Alloc& a ) noexcept; (since C++11) If possible, obtains the maximum theoretically possible allocation size from the allocator a, by calling a.max_size() If the above is not possible (e.g. a does not have the member function max_size()), then returns std::numeric_limits<size_type>::max() (until C++17) std::numeric_limits<size_type>::max()…
std::allocator_traits<Alloc>::destroy – std::allocator_traits<Alloc>::destroy Synopsis Defined in header<memory> template <class T> (since C++ 11) static void destroy(Alloc &a, T *p); Calls the destructor of the object pointed to by p. If possible, does so by calling a.destroy(p). If not possible (e.g. a does not have the member function destroy()), then calls the destructor of *p directly,…
std::allocator_traits<Alloc>::deallocate – std::allocator_traits<Alloc>::deallocate Synopsis Defined in header <memory> static void deallocate( Alloc& a, pointer p, size_type n ); (since C++11) Uses the allocator a to deallocate the storage referenced by p, by calling a.deallocate(p, n) Parameters a – allocator to use p – pointer to the previously allocated storage n – the number of objects…
std::allocator_traits<Alloc>::construct – std::allocator_traits<Alloc>::construct Synopsis Defined in header<memory> template <class T, class… Args> (since C++ 11) static void construct(Alloc &a, T *p, Args &&…args); If possible, constructs an object of type T in allocated uninitialized storage pointed to by p, by calling a.construct(p, std::forward<Args>(args)…) If the above is not possible (e.g. a does not have the…
std::allocator_traits<Alloc>::allocate – std::allocator_traits<Alloc>::allocate Synopsis Defined in header <memory> static pointer allocate( Alloc& a, size_type n ); (since C++11) (until C++20) [[nodiscard]] static pointer allocate( Alloc& a, size_type n ); (since C++20) static pointer allocate( Alloc& a, size_type n, (1) (since C++11) const_void_pointer hint ); (2) (until C++20) [[nodiscard]] static pointer allocate( Alloc& a, size_type n,…
std::allocator_traits – std::allocator_traits Synopsis Defined in header<memory> template <class Alloc> (since C++ 11) struct allocator_traits; The allocator_traits class template provides the standardized way to access various properties of Allocators. The standard containers and other standard library components access allocators through this template, which makes it possible to use any class type as an allocator, as…
std::allocator_arg_t – std::allocator_arg_t Synopsis Defined in header<memory> struct allocator_arg_t { }; (since C++ 11)(until C++ 17) struct allocator_arg_t { explicit allocator_arg_t() = default; }; (since C++ 17) std::allocator_arg_t is an empty class type used to disambiguate the overloads of constructors and member functions of allocator-aware objects, including std::tuple, std::function, std::packaged_task, (until C++17)and std::promise. See also…
std::allocator_arg – std::allocator_arg Synopsis Defined in header <memory> constexpr std::allocator_arg_t allocator_arg = std::allocator_arg_t(); (since C++11) (until C++17) inline constexpr std::allocator_arg_t allocator_arg = std::allocator_arg_t(); (since C++17) std::allocator_arg is a constant of type std::allocator_arg_t used to disambiguate, at call site, the overloads of the constructors and member functions of allocator-aware objects, such as std::tuple, std::function, std::packaged_task, (until…
std::allocator<T>::max_size – std::allocator<T>::max_size Synopsis size_type max_size() const throw(); (until C++11) (since C++11) size_type max_size() const noexcept; (deprecated in C++17) (removed in C++20) Returns the maximum theoretically possible value of n, for which the call allocate(n, 0) could succeed. In most implementations, this returns std::numeric_limits<size_type>::max() / sizeof(value_type). Parameters (none) Return value The maximum supported allocation size…
std::allocator<T>::destroy – std::allocator<T>::destroy Synopsis Defined in header <memory> void destroy( pointer p ); (until C++11) template< class U > (since C++11) void destroy( U* p ); (deprecated in C++17) (removed in C++20) Calls the destructor of the object pointed to by p 1) Calls ((T*)p)->~T() 2) Calls p->~U() Parameters p – pointer to the object…
std::allocator<T>::deallocate – std::allocator<T>::deallocate Synopsis void deallocate(T *p, std::size_t n); Deallocates the storage referenced by the pointer p, which must be a pointer obtained by an earlier call to allocate(). The argument n must be equal to the first argument of the call to allocate() that originally produced p; otherwise, the behavior is undefined. Calls ::operator_delete(void*)…
std::allocator<T>::construct – std::allocator<T>::construct Synopsis Defined in header <memory> void construct( pointer p, const_reference val ); (1) (until C++11) template< class U, class… Args > (since C++11) void construct( U* p, Args&&… args ); (2) (deprecated in C++17) (removed in C++20) Constructs an object of type T in allocated uninitialized storage pointed to by p, using…
std::allocator<T>::~allocator – std::allocator<T>::~allocator Synopsis ~allocator(); Destroys the default allocator.
std::allocator<T>::allocate – std::allocator<T>::allocate Synopsis pointer allocate(size_type n, const void *hint = 0); (1)(until C++ 17)(since C++ 17) T *allocate(std::size_t n, const void *hint); (1)(deprecated)(removed in C++ 20) T *allocate(std::size_t n); (since C++ 17)(2)(until C++ 20) [[nodiscard]] T *allocate(std::size_t n); (since C++ 20) Allocates n * sizeof(T) bytes of uninitialized storage by calling ::operator_new(std::size_t) or ::operator_new(std::size_t,…