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std::weak_ptr::expired

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C++
 
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支援を入力します (basic types, RTTI, type traits)
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std::weak_ptr
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Observers
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weak_ptr::use_count
weak_ptr::expired
weak_ptr::lock
weak_ptr::owner_before
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Non-member functions
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std::swap
 
bool expired() const;
 (C + + 11以来)
管理対象オブジェクトが既に削除されているかどうかをチェックします。 use_count() == 0に相当.
Original:
Checks whether the managed object has already been deleted. Equivalent to use_count() == 0.
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目次

[編集] パラメータ

（なし）
Original:
(none)
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[編集] 値を返します

true管理対象オブジェクトが既に削除されている場合、falseその他のとき.
Original:
true if the managed object has already been deleted, false otherwise.
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[編集] 例外

noexcept specification:  
noexcept
  (C + + 11以来)

[編集] ノート

expired()はuse_count()よりも速いかもしれません.
Original:
expired() may be faster than use_count().
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[編集] 例

ポインタの妥当性をチェックするために使用される方法を示し期限切れ.
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


[編集] も参照してください
参照されるオブジェクトを管理shared_ptrを作成します
Original:
creates a shared_ptr that manages the referenced object
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(パブリックメンバ関数) [edit]
オブジェクトを管理shared_ptrオブジェクトの数を返します
Original:
returns the number of shared_ptr objects that manage the object
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(パブリックメンバ関数) [edit]
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