std::shared_ptr<T>::swap
From cppreference.com
< cpp | memory | shared ptr
void swap( shared_ptr& r )noexcept; | (since C++11) | |
Exchanges the stored pointer values and the ownerships of *this and r. Reference counts, if any, are not adjusted.
[edit]Parameters
| r | - | smart pointer to exchange the contents with |
[edit]Return value
(none)
[edit]Example
Run this code
#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(){returnstd::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(); p1.swap(p2); print(); p1.reset(); print(); p1.swap(p2); print();}
Output:
Foo... Foo... p1=100 p2=200 p1=200 p2=100 ~Foo... p1=nullptr p2=100 p1=100 p2=nullptr ~Foo...
