std::pointer_traits

 

C++

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Utilità libreria

Tipo di supporto (basic types, RTTI, type traits)

Gestione della memoria dinamica

La gestione degli errori

Programma di utilità

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Funzione oggetti

initializer_list (C++11)

bitset

hash (C++11)

Gli operatori relazionali Original: Relational operators The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

rel_ops::operator!= rel_ops::operator> rel_ops::operator<= rel_ops::operator>=

Coppie e tuple Original: Pairs and tuples The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

pair

tuple (C++11)

piecewise_construct_t (C++11)

piecewise_construct (C++11)

Swap, in avanti e spostare Original: Swap, forward and move The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

swap

forward (C++11)

move (C++11)

move_if_noexcept (C++11)

declval (C++11)

 

Gestione della memoria dinamica

Basso livello di gestione della memoria
Allocatori Original: Allocators The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
allocator
allocator_traits (C++11)
allocator_arg_t (C++11)
allocator_arg (C++11)
uses_allocator (C++11)
scoped_allocator_adaptor (C++11)
Non inizializzata stoccaggio Original: Uninitialized storage The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
uninitialized_copy
uninitialized_copy_n (C++11)
uninitialized_fill
uninitialized_fill_n
raw_storage_iterator
get_temporary_buffer
return_temporary_buffer
Puntatori intelligenti Original: Smart pointers The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
unique_ptr (C++11)
shared_ptr (C++11)
weak_ptr (C++11)
auto_ptr (deprecato)
owner_less (C++11)
enable_shared_from_this (C++11)
bad_weak_ptr (C++11)
default_delete (C++11)
Garbage collection supporto Original: Garbage collection support The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
declare_reachable (C++11)
undeclare_reachable (C++11)
declare_no_pointers (C++11)
undeclare_no_pointers (C++11)
pointer_safety (C++11)
get_pointer_safety (C++11)
Varie Original: Miscellaneous The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
pointer_traits (C++11)
addressof (C++11)
align (C++11)
C Library Original: C Library The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
malloc calloc	realloc free

 

Elemento definito nell'header <memory>
template<class Ptr >struct pointer_traits;	(1)	(dal C++11)
template<class T >struct pointer_traits<T*>;	(2)	(dal C++11)

Il modello di classe pointer_traits fornisce il modo standard per accedere alle proprietà di alcuni tipi di puntatore di tipo. Il std::allocator_traits modello standard si basa su pointer_traits per determinare le impostazioni predefinite per diversi typedef richiede da Allocator.

Original:

The pointer_traits class template provides the standardized way to access certain properties of pointer-like types. The standard template std::allocator_traits relies on pointer_traits to determine the defaults for various typedefs requires by Allocator.

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1)

Il non specializzato pointer_traits dichiara i seguenti tipi:

Original:

The non-specialized pointer_traits declares the following types:

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Membri tipi

Tipo Original: Type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.	Definition
pointer	Ptr
element_type	Ptr::element_type se presente. In caso contrario, se TPtr è un Template<T, Args...> istanziazione di template Original: Ptr::element_type if present. Otherwise T if Ptr is a template instantiation Template<T, Args...> The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
difference_type	Ptr::difference_type se presente, altrimenti std::ptrdiff_t Original: Ptr::difference_type if present, otherwise std::ptrdiff_t The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

Membri alias modelli

Template Original: Template The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.	Definition
template <class U> using rebind	Ptr::rebind<U> se esiste, altrimenti se Tempate<U, Args...>Ptr è un Template<T, Args...> istanziazione di template Original: Ptr::rebind<U> if exists, otherwise Tempate<U, Args...> if Ptr is a template instantiation Template<T, Args...> The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

Membri funzioni

pointer_to [statico]	ottiene un puntatore dereferencable al suo argomento Original: obtains a dereferencable pointer to its argument The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico statico)

2)

Una specializzazione è previsto per i tipi di puntatore, T*, che dichiara i seguenti tipi

Original:

A specialization is provided for pointer types, T*, which declares the following types

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Membri tipi

Tipo Original: Type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.	Definition
pointer	T*
element_type	T
difference_type	std::ptrdiff_t

Membri alias modelli

Template Original: Template The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.	Definition
template< class U > using rebind	U*

Membri funzioni

pointer_to [statico]	ottiene un puntatore dereferencable al suo argomento} Original: obtains a dereferencable pointer to its argument} The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico statico)

Note

Le riassociare alias modello utente permette, dato un puntatore come tipo che punta a T, per ottenere lo stesso puntatore come tipo che punta a U. Per esempio,

Original:

The rebind member template alias makes it possible, given a pointer-like type that points to T, to obtain the same pointer-like type that points to U. For example,

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std :: is_same <std :: pointer_traits <std :: shared_ptr <int>> :: Rebind <double>, std :: unique_ptr <double>> :: valore), "")

Original:

std::is_same<std::pointer_traits< std::shared_ptr<int>>::rebind<double>, std::unique_ptr<double> >::value), "")

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Esempio

#include <memory>#include <iostream>   template<class Ptr>struct BlockList {// Predefine a memory block struct block;   // Define a pointer to a memory block from the kind of pointer Ptr s// If Ptr is any kind of T*, block_ptr_t is block*// If Ptr is smart_ptr<T>, block_ptr_t is smart_ptr<block>typedeftypename std::pointer_traits<Ptr>::template rebind<block> block_ptr_t;   struct block {std::size_t size; block_ptr_t next_block;};   block_ptr_t free_blocks;};   int main(){ BlockList<int*> bl1;// The type of bl1.free_blocks is block*   BlockList<std::shared_ptr<char>> bl2;// The type of bl2.free_blocks is std::shared_ptr<block>std::cout<< bl2.free_blocks.use_count()<<'\n';}

Output:

​0​

Vedi anche

allocator_traits (C++11)	fornisce informazioni sui tipi di allocatore Original: provides information about allocator types The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (classe template)
addressof (C++11)	ottiene l'indirizzo reale di un oggetto, anche se l'operatore &' è sovraccarico Original: obtains actual address of an object, even if the & operator is overloaded The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (funzione di modello)