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std:: swap (std::shared_ptr)

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std::shared_ptr
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swap (std::shared_ptr)
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Definiert im Header <memory>
template < class T >
void swap ( std:: shared_ptr < T > & lhs, std:: shared_ptr < T > & rhs ) noexcept ;
(seit C++11)

Spezialisiert den std::swap -Algorithmus für std:: shared_ptr . Tauscht die Inhalte von lhs und rhs . Ruft lhs. swap ( rhs ) auf.


Inhaltsverzeichnis

Parameter

lhs, rhs - Smart Pointer, deren Inhalte ausgetauscht werden sollen

Rückgabewert

(keine)

Komplexität

Konstante.

Beispiel

Diesen Code ausführen 
#include <iostream>
#include <memory>
#include <string>
struct Foo {
    Foo(int _val) : val(_val) { std::cout << "Foo...\n"; }
    ~Foo() { std::cout << "~Foo...\n"; }
    std::string print() { return std::to_string(val); }
    int val;
};
int main()
{
    std::shared_ptr<Foo> p1 = std::make_shared<Foo>(100);
    std::shared_ptr<Foo> p2 = std::make_shared<Foo>(200);
    auto print = [&]() {
        std::cout << " p1=" << (p1 ? p1->print() : "nullptr");
        std::cout << " p2=" << (p2 ? p2->print() : "nullptr") << '\n';  
    };
    print();
    std::swap(p1, p2);
    print();
    p1.reset();
    print();
    std::swap(p1, p2);
    print();   
}

Ausgabe: 

Foo...
Foo...
 p1=100 p2=200
 p1=200 p2=100
~Foo...
 p1=nullptr p2=100
 p1=100 p2=nullptr
~Foo...

Siehe auch

tauscht die Werte zweier Objekte
(Funktions-Template)
tauscht die Inhalte
(öffentliche Elementfunktion)