std::unique_ptr<T,Deleter>::operator*, std::unique_ptr<T,Deleter>::operator->

 

C++

Compiler support

Freestanding and hosted

Language

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)

Technical specifications

Symbols index

External libraries

 

Memory management library

voidify (exposition only*) Uninitialized memory algorithms uninitialized_copy uninitialized_fill uninitialized_move (C++17) uninitialized_default_construct (C++17) uninitialized_value_construct (C++17) destroy (C++17) destroy_at (C++17) uninitialized_copy_n (C++11) uninitialized_fill_n uninitialized_move_n (C++17) uninitialized_default_construct_n (C++17) uninitialized_value_construct_n (C++17) destroy_n (C++17) construct_at (C++20) Constrained uninitialized memory algorithms ranges::uninitialized_copy (C++20) ranges::uninitialized_fill (C++20) ranges::uninitialized_move (C++20) ranges::construct_at (C++20) ranges::destroy (C++20) ranges::destroy_n (C++20) ranges::destroy_at (C++20) ranges::uninitialized_copy_n (C++20) ranges::uninitialized_fill_n (C++20) ranges::uninitialized_move_n (C++20) ranges::uninitialized_default_construct (C++20) ranges::uninitialized_value_construct (C++20) ranges::uninitialized_default_construct_n (C++20)  ranges::uninitialized_value_construct_n (C++20) C Library malloc calloc realloc aligned_alloc (C++17) free

Allocators allocator allocator_traits (C++11) allocation_result (C++23) allocator_arg (C++11) uses_allocator (C++11) uses_allocator_construction_args (C++20) make_obj_using_allocator (C++20) uninitialized_construct_using_allocator (C++20)  scoped_allocator_adaptor (C++11) pmr::polymorphic_allocator (C++17) Memory resources pmr::memory_resource (C++17) pmr::get_default_resource (C++17) pmr::set_default_resource (C++17) pmr::new_delete_resource (C++17) pmr::null_memory_resource (C++17) pmr::synchronized_pool_resource (C++17) pmr::unsynchronized_pool_resource (C++17) pmr::monotonic_buffer_resource (C++17) pmr::pool_options (C++17) Garbage collection support declare_reachable (C++11)(until C++23) undeclare_reachable (C++11)(until C++23) declare_no_pointers (C++11)(until C++23) undeclare_no_pointers (C++11)(until C++23) pointer_safety (C++11)(until C++23) get_pointer_safety (C++11)(until C++23) Uninitialized storage raw_storage_iterator (until C++20*) get_temporary_buffer (until C++20*) return_temporary_buffer (until C++20*) Explicit lifetime management start_lifetime_asstart_lifetime_as_array (C++23)(C++23)

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) Low level memory management operator new operator new[] operator delete operator delete[] get_new_handler (C++11) set_new_handler launder (C++17) bad_alloc bad_array_new_length (C++11) nothrow_t align_val_t (C++17) destroying_delete_t (C++20) new_handler nothrow Miscellaneous pointer_traits (C++11) to_address (C++20) addressof (C++11) align (C++11) assume_aligned (C++20) is_sufficiently_aligned (C++26)

 

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>

 

typename std::add_lvalue_reference<T>::type operator*() const     noexcept(noexcept(*std::declval<pointer>()));	(1)	(since C++11) (constexpr since C++23)
pointer operator->() const noexcept;	(2)	(since C++11) (constexpr since C++23)

operator* and operator-> provide access to the object owned by *this.

These member functions are only provided for unique_ptr for the single objects i.e. the primary template.

1) If std::reference_converts_from_temporary_v     <std::add_lvalue_reference_t<T>,      decltype(*std::declval<pointer>())> is true, the program is ill-formed.

(since C++23)

If get() is a null pointer, the behavior is undefined.

Return value

1) Returns the object owned by *this, equivalent to *get().

2) Returns a pointer to the object owned by *this, i.e. get().

Exceptions

1) May throw if pointer has a throwing operator*.

Notes

The use of std::add_lvalue_reference is to make it possible to instantiate std::unique_ptr<void> since void& isn't allowed in C++ while std::add_lvalue_reference<void> produces void. See LWG673 for details.

Example

Run this code

#include <iostream>
#include <memory>
 
struct Foo
{
    void bar() { std::cout << "Foo::bar\n"; }
};
 
void f(const Foo&) 
{
    std::cout << "f(const Foo&)\n";
}
 
int main() 
{
    std::unique_ptr<Foo> ptr(new Foo);
 
    ptr->bar();
    f(*ptr);
}

Output:

Foo::bar
f(const Foo&)

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 2762	C++11	operator* might be potentially-throwing even if *get() was noexcept	added a conditional exception specification
LWG 4148	C++23	operator* could return a dangling reference if element_type* differs from Deleter::pointer	the program is ill- formed in this case

See also

get	returns a pointer to the managed object (public member function)