operator==,!=,<,<=,>,>=,<=>(std::unique_ptr)
Defined in header <memory> |
||
---|---|---|
template< class T1, class D1, class T2, class D2 > bool operator==( const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y ); |
(1) | (since C++11) (constexpr since C++23) |
template< class T1, class D1, class T2, class D2 > bool operator!=( const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y ); |
(2) | (since C++11) (until C++20) |
template< class T1, class D1, class T2, class D2 > bool operator<( const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y ); |
(3) | (since C++11) |
template< class T1, class D1, class T2, class D2 > bool operator<=( const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y ); |
(4) | (since C++11) |
template< class T1, class D1, class T2, class D2 > bool operator>( const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y ); |
(5) | (since C++11) |
template< class T1, class D1, class T2, class D2 > bool operator>=( const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y ); |
(6) | (since C++11) |
template< class T1, class D1, class T2, class D2 > requires std::three_way_comparable_with< typename unique_ptr<T1, D1>::pointer, typename unique_ptr<T2, D2>::pointer> std::compare_three_way_result_t<typename unique_ptr<T1, D1>::pointer, typename unique_ptr<T2, D2>::pointer> operator<=>( const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y ); |
(7) | (since C++20) |
template< class T, class D > bool operator==( const unique_ptr<T, D>& x, std::nullptr_t) noexcept; |
(8) | (since C++11) (constexpr since C++23) |
template< class T, class D > bool operator==(std::nullptr_t, const unique_ptr<T, D>& x) noexcept; |
(9) | (since C++11) (until C++20) |
template< class T, class D > bool operator!=( const unique_ptr<T, D>& x, std::nullptr_t) noexcept; |
(10) | (since C++11) (until C++20) |
template< class T, class D > bool operator!=(std::nullptr_t, const unique_ptr<T, D>& x) noexcept; |
(11) | (since C++11) (until C++20) |
template< class T, class D > bool operator<( const unique_ptr<T, D>& x, std::nullptr_t ); |
(12) | (since C++11) (constexpr since C++23) |
template< class T, class D > bool operator<(std::nullptr_t, const unique_ptr<T, D>& y ); |
(13) | (since C++11) (constexpr since C++23) |
template< class T, class D > bool operator<=( const unique_ptr<T, D>& x, std::nullptr_t ); |
(14) | (since C++11) (constexpr since C++23) |
template< class T, class D > bool operator<=(std::nullptr_t, const unique_ptr<T, D>& y ); |
(15) | (since C++11) (constexpr since C++23) |
template< class T, class D > bool operator>( const unique_ptr<T, D>& x, std::nullptr_t ); |
(16) | (since C++11) (constexpr since C++23) |
template< class T, class D > bool operator>(std::nullptr_t, const unique_ptr<T, D>& y ); |
(17) | (since C++11) (constexpr since C++23) |
template< class T, class D > bool operator>=( const unique_ptr<T, D>& x, std::nullptr_t ); |
(18) | (since C++11) (constexpr since C++23) |
template< class T, class D > bool operator>=(std::nullptr_t, const unique_ptr<T, D>& y ); |
(19) | (since C++11) (constexpr since C++23) |
template< class T, class D > requires std::three_way_comparable<typename unique_ptr<T, D>::pointer> std::compare_three_way_result_t<typename unique_ptr<T, D>::pointer> operator<=>( const unique_ptr<T, D>& x, std::nullptr_t ); |
(20) | (since C++20) (constexpr since C++23) |
Compares the pointer values of two unique_ptr
s, or a unique_ptr
and nullptr
.
1-7) Compares two
unique_ptr
s
8-20) Compares a
unique_ptr
and
nullptr
.
The |
(since C++20) |
Parameters
x, y | - | unique_ptr s to compare |
Return value
1)
x.get() == y.get()
2)
x.get() != y.get()
3)
std::less<CT>()(x.get(), y.get())
, where
CT
is
std::common_type<unique_ptr<T1, D1>::pointer, unique_ptr<T2, D2>::pointer>::type
4)
!(y < x)
5)
y < x
6)
!(x < y)
7)
std::compare_three_way{}(x.get(), y.get())
8-9)
!x
10-11)
(bool)x
12)
std::less<unique_ptr<T,D>::pointer>()(x.get(), nullptr)
13)
std::less<unique_ptr<T,D>::pointer>()(nullptr, y.get())
14)
!(nullptr < x)
15)
!(y < nullptr)
16)
nullptr < x
17)
y < nullptr
18)
!(x < nullptr)
19)
!(nullptr < y)
20)
std::compare_three_way{}(x.get(), static_cast<typename unique_ptr<T, D>::pointer>(nullptr))
Example
#include <iostream> #include <memory> int main() { std::unique_ptr<int> p1(new int(42)); std::unique_ptr<int> p2(new int(42)); std::cout << std::boolalpha << "(p1 == p1) : " << (p1 == p1) << '\n' << "(p1 <=> p1) == 0 : " << ((p1 <=> p1) == 0) << '\n' // Since C++20 // p1 and p2 point to different memory locations, so p1 != p2 << "(p1 == p2) : " << (p1 == p2) << '\n' << "(p1 < p2) : " << (p1 < p2) << '\n' << "(p1 <=> p2) < 0 : " << ((p1 <=> p2) < 0) << '\n' // Since C++20 << "(p1 <=> p2) == 0 : " << ((p1 <=> p2) == 0) << '\n'; // Since C++20 }
Possible output:
(p1 == p1) : true (p1 <=> p1) == 0 : true (p1 == p2) : false (p1 < p2) : true (p1 <=> p2) < 0 : true (p1 <=> p2) == 0 : false
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 3426 | C++20 | operator<=>(unique_ptr, nullptr_t) was ill-formed |
constraints and definition fixed |
See also
returns a pointer to the managed object (public member function) |
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