std::swap(std::unique_ptr)
From cppreference.com
< cpp | memory | unique ptr
| Defined in header <memory>
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| template< class T, class D > void swap( std::unique_ptr<T, D>& lhs, std::unique_ptr<T, D>& rhs ) noexcept; |
(since C++11) (constexpr since C++23) |
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Specializes the std::swap algorithm for std::unique_ptr. Swaps the contents of lhs and rhs. Calls lhs.swap(rhs).
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This function does not participate in overload resolution unless std::is_swappable_v<D> is true. |
(since C++17) |
Parameters
| lhs, rhs | - | smart pointers whose contents to swap |
Return value
(none)
Complexity
Constant.
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() { return std::to_string(val); } int val; }; int main() { std::unique_ptr<Foo> p1 = std::make_unique<Foo>(100); std::unique_ptr<Foo> p2 = std::make_unique<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(); }
Output:
Foo... Foo... p1=100 p2=200 p1=200 p2=100 ~Foo... p1=nullptr p2=100 p1=100 p2=nullptr ~Foo...
See also
| swaps the values of two objects (function template) | |
| swaps the contents (public member function) |