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std::weak_ptr::expired

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< cpp‎ | memory‎ | weak ptr

 
 
 
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Zuweiser
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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
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Uninitialized storage
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uninitialized_copy
uninitialized_copy_n(C++11)
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Intelligente Zeiger
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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
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Garbage collection support
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Miscellaneous
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pointer_traits(C++11)
addressof(C++11)
align(C++11)
C-Bibliothek
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C Library
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std::weak_ptr
Member-Funktionen
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Member functions
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weak_ptr::weak_ptr
weak_ptr::~weak_ptr
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Modifiers
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Modifiers
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weak_ptr::reset
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Beobachter
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Observers
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weak_ptr::use_count
weak_ptr::expired
weak_ptr::lock
weak_ptr::owner_before
Non-Member-Funktionen
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Non-member functions
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std::swap
 
bool expired() const;
(seit C++11)
Überprüft, ob das verwaltete Objekt wurde bereits gelöscht. Entspricht use_count() == 0 .
Original:
Checks whether the managed object has already been deleted. Equivalent to use_count() == 0.
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Inhaltsverzeichnis

[Bearbeiten] Parameter

(None)
Original:
(none)
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[Bearbeiten] Rückgabewert

true wenn das verwaltete Objekt bereits gelöscht wurde, false sonst .
Original:
true if the managed object has already been deleted, false otherwise.
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[Bearbeiten] Ausnahmen

noexcept specification:  
noexcept
  (seit C++11)

[Bearbeiten] Notes

expired() kann schneller sein als use_count() .
Original:
expired() may be faster than use_count().
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[Bearbeiten] Beispiel

Veranschaulicht, wie abgelaufene verwendet wird, um die Gültigkeit des Zeigers überprüfen .
Original:
Demonstrates how expired is used to check validity of the pointer.
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#include <iostream>
#include <memory>
 
std::weak_ptr<int> gw;
 
void f()
{
    if (!gw.expired()) {
	std::cout << "gw is valid\n";
    }
    else {
        std::cout << "gw is expired\n";
    }
}
 
int main()
{
    {
        auto sp = std::make_shared<int>(42);
	gw = sp;
 
	f();
    }
 
    f();
}

Output:

gw is valid
gw is expired


[Bearbeiten] Siehe auch

schafft eine shared_ptr, die das referenzierte Objekt verwaltet
Original:
creates a shared_ptr that manages the referenced object
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(öffentliche Elementfunktion) [edit]
gibt die Anzahl der shared_ptr Objekte, die das Objekt verwalten
Original:
returns the number of shared_ptr objects that manage the object
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(öffentliche Elementfunktion) [edit]