std::unique_ptr<T,Deleter>::release

 

C++

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Freestanding and hosted

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Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Diagnostics library

Memory management library

Metaprogramming library (C++11)

General utilities library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Strings library

Text processing library

Numerics library

Date and time library

Input/output library

Filesystem library (C++17)

Concurrency support library (C++11)

Execution control library (C++26)

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Symbols index

External libraries

 

Memory management library

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Low level memory management operator newoperator new[] operator deleteoperator delete[] nothrow_t nothrow new_handler set_new_handler get_new_handler (C++11) bad_alloc bad_array_new_length (C++11) align_val_t (C++17) destroying_delete_t (C++20) launder (C++17) Smart pointers unique_ptr (C++11) shared_ptr (C++11) weak_ptr (C++11) auto_ptr (until C++17*) owner_less (C++11) owner_less<void> (C++17) owner_hash (C++26) owner_equal (C++26) enable_shared_from_this (C++11) bad_weak_ptr (C++11) default_delete (C++11) out_ptr_t (C++23) inout_ptr_t (C++23) Miscellaneous pointer_traits (C++11) to_address (C++20) addressof (C++11) align (C++11) assume_aligned (C++20) is_sufficiently_aligned (C++26) C Library malloc calloc realloc free aligned_alloc (C++17)

 

std::unique_ptr

Member functions

unique_ptr::unique_ptr

unique_ptr::~unique_ptr

unique_ptr::operator=

Modifiers

unique_ptr::release

unique_ptr::reset

unique_ptr::swap

Observers

unique_ptr::get

unique_ptr::get_deleter

unique_ptr::operator bool

unique_ptr::operator*unique_ptr::operator->

unique_ptr::operator[]

Non-member functions

make_uniquemake_unique_for_overwrite (C++14)(C++20)

operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(C++20)

operator<< (C++20)

swap(std::unique_ptr)

Helper classes

hash<std::unique_ptr>

 

pointer release() noexcept;		(since C++11) (constexpr since C++23)

Releases the ownership of the managed object, if any.

get() returns nullptr after the call.

The caller is responsible for cleaning up the object (e.g. by use of get_deleter()).

Parameters

(none)

Return value

Pointer to the managed object or nullptr if there was no managed object, i.e. the value which would be returned by get() before the call.

Example

Run this code

#include <cassert>
#include <iostream>
#include <memory>
 
struct Foo
{
    Foo() { std::cout << "Foo\n"; }
    ~Foo() { std::cout << "~Foo\n"; }
};
 
/ Ownership of the Foo resource is transferred when calling this function
void legacy_api(Foo* owning_foo)
{
    std::cout << __func__ << '\n';
    / [legacy code that no one understands or dares touch anymore]
    / [...]
    delete owning_foo;
}
 
int main()
{
    std::unique_ptr<Foo> managed_foo(new Foo);
    / [code that might return or throw or some such]
    / [...]
    legacy_api(managed_foo.release();
 
    assert(managed_foo == nullptr);
}

Output:

Foo
legacy_api
~Foo

See also

get	returns a pointer to the managed object (public member function)
get_deleter	returns the deleter that is used for destruction of the managed object (public member function)
reset	replaces the managed object (public member function)

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