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      std::weak_ptr

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      < cpp‎ | memory

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      rel_ops::operator!=
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      Swap, forward and move
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      std::weak_ptr
      Funções de membro
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      Member functions
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      weak_ptr::weak_ptr
      weak_ptr::~weak_ptr
      weak_ptr::operator=
      Modificadores
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      Modifiers
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      weak_ptr::reset
      weak_ptr::swap
      Observadores
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      Observers
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      weak_ptr::use_count
      weak_ptr::expired
      weak_ptr::lock
      weak_ptr::owner_before
      Não-membros funções
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      Definido no cabeçalho <memory>
      template<class T >class weak_ptr;
      		(desde C++11)
      std::weak_ptr é um ponteiro inteligente que contém um não-proprietária de referência ("fraco") a um objeto que é gerenciado pelo std::shared_ptr. Ele deve ser convertido para std::shared_ptr para acessar o objeto referenciado.
      Original:
      std::weak_ptr is a smart pointer that holds a non-owning ("weak") reference to an object that is managed by std::shared_ptr. It must be converted to std::shared_ptr in order to access the referenced object.
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      std::weak_ptr modelos de propriedade temporária:. quando um objeto precisa ser acessado somente se ele existe, e ele pode ser excluído a qualquer momento por outra pessoa, std::weak_ptr é usado para rastrear o objeto, e ele é convertido para std::shared_ptr para assumir a propriedade temporária. std::shared_ptr Se o original é destruído neste momento, a vida útil do objeto é prorrogado até o std::shared_ptr temporário é destruído, bem.
      Original:
      std::weak_ptr models temporary ownership: when an object needs to be accessed only if it exists, and it may be deleted at any time by someone else, std::weak_ptr is used to track the object, and it is converted to std::shared_ptr to assume temporary ownership. If the original std::shared_ptr is destroyed at this time, the object's lifetime is extended until the temporary std::shared_ptr is destroyed as well.
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      Além disso, std::weak_ptr é usado para quebrar as referências circulares de std::shared_ptr.
      Original:
      In addition, std::weak_ptr is used to break circular references of std::shared_ptr.
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      Índice

      [editar]Tipos de membro

      Tipo de membro
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      Member type
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      		 Definition
      element_typeT

      [editar]Funções de membro

      cria um novo weak_ptr
      Original:
      creates a new weak_ptr
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      (função pública membro)[edit]
      destrói uma weak_ptr
      Original:
      destroys a weak_ptr
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      (função pública membro)[edit]
      atribui o weak_ptr
      Original:
      assigns the weak_ptr
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      (função pública membro)[edit]
      Modificadores
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      Modifiers
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      libera a propriedade do objeto gerenciado
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      releases the ownership of the managed object
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      (função pública membro)[edit]
      troca os objetos gerenciados
      Original:
      swaps the managed objects
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      (função pública membro)[edit]
      Observadores
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      Observers
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      retorna o número de objetos shared_ptr que gerenciam o objeto
      Original:
      returns the number of shared_ptr objects that manage the object
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      (função pública membro)[edit]
      Verifica se o objeto referenciado já foi excluído
      Original:
      checks whether the referenced object was already deleted
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      (função pública membro)[edit]
      cria um shared_ptr que gerencia o objeto referenciado
      Original:
      creates a shared_ptr that manages the referenced object
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      (função pública membro)[edit]
      fornece-proprietário baseado ordenação dos ponteiros fracos
      Original:
      provides owner-based ordering of weak pointers
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      (função pública membro)[edit]

      [editar]Não-membros funções

      (C++11)
      o algoritmo especializado std::swap
      Original:
      specializes the std::swap algorithm
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      (modelo de função)[edit]

      [editar]Exemplo

      Demonstra como bloqueio é usado para garantir a validade do ponteiro .
      Original:
      Demonstrates how lock is used to ensure validity of the pointer.
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      #include <iostream>#include <memory>   std::weak_ptr<int> gw;   void f(){if(auto spt = gw.lock()){// Has to be copied into a shared_ptr before usagestd::cout<<*spt <<"\n";}else{std::cout<<"gw is expired\n";}}   int main(){{auto sp =std::make_shared<int>(42); gw = sp;   f();}   f();}

      Saída: 

      42 gw is expired
      Obtida de "https://pt.cppreference.com/mwiki/index.php?title=cpp/memory/weak_ptr&oldid=21169"
      close