< cpp‎ | memory‎ | unique ptr
unique_ptr& operator=( unique_ptr&& r );
(1) (since C++11)
template< class U, class E >
unique_ptr& operator=( unique_ptr<U,E>&& r );
(1) (since C++11)
unique_ptr& operator=( nullptr_t );
(2) (since C++11)
1) Transfers ownership from r to *this as if by calling reset(r.release()) followed by an assignment of get_deleter() from std::forward<E>(r.get_deleter()). If Deleter is not a reference type, requires that it is nothrow-MoveAssignable. If Deleter is a reference type, requires that std::remove_reference<Deleter>::type is nothrow-CopyAssignable. The template version of this assignment operator only participates in overload resolution if U is not an array type and unique_ptr<U,E>::pointer is implicitly convertible to pointer.
2) Effectively the same as calling reset().

Note that unique_ptr's assignment operator only accepts xvalues, which are typically generated by std::move. (The unique_ptr class explicitly deletes its lvalue copy constructor and lvalue assignment operator.)


[edit] Parameters

r - smart pointer from which ownership will be transfered

[edit] Return value


[edit] Exceptions

noexcept specification:  

[edit] Example

#include <iostream>
#include <memory>
struct Foo {
    Foo() { std::cout << "Foo\n"; }
    ~Foo() { std::cout << "~Foo\n"; }
int main() 
    std::unique_ptr<Foo> p1;
        std::cout << "Creating new Foo...\n";
        std::unique_ptr<Foo> p2(new Foo);
        // p1 = p2; // Error ! can't copy unique_ptr
        p1 = std::move(p2);
        std::cout << "About to leave inner block...\n";
        // Foo instance will continue to live, 
        // despite p2 going out of scope
    std::cout << "About to leave program...\n";


Creating new Foo...
About to leave inner block...
About to leave program...