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    std::pointer_traits

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    C++
     
    Utilities-Bibliothek
     
    Dynamische Speicherverwaltung
    Low-Level-Speicherverwaltung
    Zuweiser
    Original:
    Allocators
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    allocator
    allocator_traits(C++11)
    allocator_arg_t(C++11)
    allocator_arg(C++11)
    uses_allocator(C++11)
    scoped_allocator_adaptor(C++11)
    Initialisierter Speicher
    Original:
    Uninitialized storage
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    uninitialized_copy
    uninitialized_copy_n(C++11)
    uninitialized_fill
    uninitialized_fill_n
    raw_storage_iterator
    get_temporary_buffer
    return_temporary_buffer
    Intelligente Zeiger
    Original:
    Smart pointers
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    unique_ptr(C++11)
    shared_ptr(C++11)
    weak_ptr(C++11)
    auto_ptr(veraltet)
    owner_less(C++11)
    enable_shared_from_this(C++11)
    bad_weak_ptr(C++11)
    default_delete(C++11)
    Garbage Collection Unterstützung
    Original:
    Garbage collection support
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    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)
    Verschiedenes
    Original:
    Miscellaneous
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    pointer_traits(C++11)
    addressof(C++11)
    align(C++11)
    C-Bibliothek
    Original:
    C Library
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    definiert in Header <memory>
    template<class Ptr >struct pointer_traits;
    		 (1) (seit C++11)
    template<class T >struct pointer_traits<T*>;
    		 (2) (seit C++11)
    Die pointer_traits Klassen-Template bietet die standardisierte Möglichkeit, bestimmte Eigenschaften der Zeiger-ähnliche Typen zugreifen. Das Standard-Template std::allocator_traits setzt auf pointer_traits, um die Standardeinstellungen für verschiedene typedefs bestimmen erfordert von 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)
    Die nicht-spezialisierten pointer_traits erklärt die folgenden Typen:
    Original:
    The non-specialized pointer_traits declares the following types:
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    Inhaltsverzeichnis

    [Bearbeiten]Mitglied Typen

    Type
    Original:
    Type
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    		 Definition
    pointerPtr
    element_type
    Ptr::element_type falls vorhanden. Ansonsten T wenn Ptr ist eine Vorlage Instanziierung Template<T, Args...>
    Original:
    Ptr::element_type if present. Otherwise T if Ptr is a template instantiation Template<T, Args...>
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    difference_type
    Ptr::difference_type falls vorhanden, sonst std::ptrdiff_t
    Original:
    Ptr::difference_type if present, otherwise std::ptrdiff_t
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    [Bearbeiten]Mitglied alias Vorlagen

    Template
    Original:
    Template
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    		 Definition
    template <class U> using rebind
    Ptr::rebind<U> wenn vorhanden, sonst Tempate<U, Args...> wenn Ptr ist eine Vorlage Instanziierung Template<T, Args...>
    Original:
    Ptr::rebind<U> if exists, otherwise Tempate<U, Args...> if Ptr is a template instantiation Template<T, Args...>
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    [Bearbeiten]Member-Funktionen

    [statisch]
    erhält eine dereferencable Zeiger auf sein Argument
    Original:
    obtains a dereferencable pointer to its argument
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    (public static Elementfunktion)
    2)
    Eine Spezialisierung ist für Zeigertypen, T*, die die folgenden Arten bereitgestellt erklärt
    Original:
    A specialization is provided for pointer types, T*, which declares the following types
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    [Bearbeiten]Mitglied Typen

    Type
    Original:
    Type
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    		 Definition
    pointerT*
    element_typeT
    difference_typestd::ptrdiff_t

    [Bearbeiten]Mitglied alias Vorlagen

    Template
    Original:
    Template
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    		 Definition
    template< class U > using rebind U*

    [Bearbeiten]Member-Funktionen

    [statisch]
    erhält eine dereferencable Zeiger auf das Argument}
    Original:
    obtains a dereferencable pointer to its argument}
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    (public static Elementfunktion)

    [Bearbeiten]Notes

    Die rebind Elementtemplate Alias ​​ist es möglich, da ein Zeiger-ähnliche Aktivität, die auf T, um die gleiche wie Typ-Zeiger, der auf U. Beispielsweise erhalten
    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>> :: value), "")
    Original:
    std::is_same<std::pointer_traits< std::shared_ptr<int>>::rebind<double>, std::unique_ptr<double> >::value), "")
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    [Bearbeiten]Beispiel

    #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​

    [Bearbeiten]Siehe auch

    (C++11)
    		 liefert Informationen über Allokatoren
    (Klassen-Template)[edit]
    (C++11)
    		 ermittelt die tatsächlichen Adresse eines Objekts, selbst wenn der Dereferenzierungsoperator überladen ist
    (Funktions-Template)[edit]
    Von „https://de.cppreference.com/mwiki/index.php?title=cpp/memory/pointer_traits&oldid=29428“
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