W3cubDocs

/C++

std::shared_ptr<T>::operator==, !=, <, <=, >, >=

Compare two `shared_ptr` objects
template < class T, class U > bool operator==( const shared_ptr<T>& lhs, const shared_ptr<U>& rhs ) noexcept;	(1)	(since C++11)
template< class T, class U > bool operator!=( const shared_ptr<T>& lhs, const shared_ptr<U>& rhs ) noexcept;	(2)	(since C++11)
template< class T, class U > bool operator<( const shared_ptr<T>& lhs, const shared_ptr<U>& rhs ) noexcept;	(3)	(since C++11)
template< class T, class U > bool operator>( const shared_ptr<T>& lhs, const shared_ptr<U>& rhs ) noexcept;	(4)	(since C++11)
template< class T, class U > bool operator<=( const shared_ptr<T>& lhs, const shared_ptr<U>& rhs ) noexcept;	(5)	(since C++11)
template< class T, class U > bool operator>=( const shared_ptr<T>& lhs, const shared_ptr<U>& rhs ) noexcept;	(6)	(since C++11)
Compare a `shared_ptr` with a null pointer
template< class T > bool operator==( const shared_ptr<T>& lhs, std::nullptr_t rhs ) noexcept;	(7)	(since C++11)
template< class T > bool operator==( std::nullptr_t lhs, const shared_ptr<T>& rhs ) noexcept;	(8)	(since C++11)
template< class T > bool operator!=( const shared_ptr<T>& lhs, std::nullptr_t rhs ) noexcept;	(9)	(since C++11)
template< class T > bool operator!=( std::nullptr_t lhs, const shared_ptr<T>& rhs ) noexcept;	(10)	(since C++11)
template< class T > bool operator<( const shared_ptr<T>& lhs, std::nullptr_t rhs ) noexcept;	(11)	(since C++11)
template< class T > bool operator<( std::nullptr_t lhs, const shared_ptr<T>& rhs ) noexcept;	(12)	(since C++11)
template< class T > bool operator>( const shared_ptr<T>& lhs, std::nullptr_t rhs ) noexcept;	(13)	(since C++11)
template< class T > bool operator>( std::nullptr_t lhs, const shared_ptr<T>& rhs ) noexcept;	(14)	(since C++11)
template< class T > bool operator<=( const shared_ptr<T>& lhs, std::nullptr_t rhs ) noexcept;	(15)	(since C++11)
template< class T > bool operator<=( std::nullptr_t lhs, const shared_ptr<T>& rhs ) noexcept;	(16)	(since C++11)
template< class T > bool operator>=( const shared_ptr<T>& lhs, std::nullptr_t rhs ) noexcept;	(17)	(since C++11)
template< class T > bool operator>=( std::nullptr_t lhs, const shared_ptr<T>& rhs ) noexcept;	(18)	(since C++11)

Compares two shared_ptr<T> objects or compares shared_ptr<T> with a null pointer.

Note that the comparison operators for shared_ptr simply compare pointer values; the actual objects pointed to are not compared. Having operator< defined for shared_ptr allows shared_ptrs to be used as keys in associative containers, like std::map and std::set.

Parameters

lhs	-	the left-hand `shared_ptr` to compare
rhs	-	the right-hand `shared_ptr` to compare

Return value

1) lhs.get() == rhs.get()

2) !(lhs == rhs)

3) std::less<V>()(lhs.get(), rhs.get()), where V is the composite pointer type of std::shared_ptr<T>::element_type* and std::shared_ptr<U>::element_type*

4) rhs < lhs

5) !(rhs < lhs)

6) !(lhs < rhs)

7) !lhs

8) !rhs

9) (bool)lhs

10) (bool)rhs

11) std::less<std::shared_ptr<T>::element_type*>()(lhs.get(), nullptr)

12) std::less<std::shared_ptr<T>::element_type*>()(nullptr, rhs.get())

13) nullptr < lhs

14) rhs < nullptr

15) !(nullptr < lhs)

16) !(rhs < nullptr)

17) !(lhs < nullptr)

18) !(nullptr < rhs)

Notes

In all cases, it is the stored pointer (the one returned by get()) that is compared, rather than the managed pointer (the one passed to the deleter when use_count goes to zero). The two pointers may differ in a shared_ptr created using the aliasing constructor.

W3cubDocs

std::shared_ptr<T>::operator==, !=, <, <=, >, >=

Parameters

Return value

Notes

Example

See also