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std::weak_ptr::expired

Da cppreference.com.
< cpp‎ | memory‎ | weak ptr

 
 
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std::weak_ptr
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weak_ptr::use_count
weak_ptr::expired
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Non-member functions
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std::swap
 
bool expired() const;
(dal C++11)
Controlla se l'oggetto gestito è già stato cancellato. Equivalente a use_count() == 0.
Original:
Checks whether the managed object has already been deleted. Equivalent to use_count() == 0.
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Indice

[modifica] Parametri

(Nessuno)
Original:
(none)
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[modifica] Valore di ritorno

true se l'oggetto gestito è già stato eliminato, false altrimenti.
Original:
true if the managed object has already been deleted, false otherwise.
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[modifica] Eccezioni

noexcept specification:  
noexcept
  (dal C++11)

[modifica] Note

expired() può essere più veloce use_count().
Original:
expired() may be faster than use_count().
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[modifica] Esempio

Viene illustrato come scaduto viene utilizzato per controllare la validità del puntatore .
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


[modifica] Vedi anche

crea un shared_ptr che gestisce l'oggetto indicato
Original:
creates a shared_ptr that manages the referenced object
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(membro pubblico funzione) [edit]
restituisce il numero di oggetti shared_ptr che gestiscono l'oggetto
Original:
returns the number of shared_ptr objects that manage the object
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(membro pubblico funzione) [edit]