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

From cppreference.com
< cpp‎ | memory‎ | shared ptr
 
 
 
 
 
Compare two shared_ptr objects
template < class T, class U >
bool operator==( const shared_ptr<T>& lhs, const shared_ptr<U>& rhs );
(1) (since C++11)
template< class T, class U >
bool operator!=( const shared_ptr<T>& lhs, const shared_ptr<U>& rhs );
(2) (since C++11)
template< class T, class U >
bool operator<( const shared_ptr<T>& lhs, const shared_ptr<U>& rhs );
(3) (since C++11)
template< class T, class U >
bool operator>( const shared_ptr<T>& lhs, const shared_ptr<U>& rhs );
(4) (since C++11)
template< class T, class U >
bool operator<=( const shared_ptr<T>& lhs, const shared_ptr<U>& rhs );
(5) (since C++11)
template< class T, class U >
bool operator>=( const shared_ptr<T>& lhs, const shared_ptr<U>& rhs );
(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 );
(7) (since C++11)
template< class T >
bool operator==( std::nullptr_t lhs, const shared_ptr<T>& rhs );
(8) (since C++11)
template< class T >
bool operator!=( const shared_ptr<T>& lhs, std::nullptr_t rhs );
(9) (since C++11)
template< class T >
bool operator!=( std::nullptr_t lhs, const shared_ptr<T>& rhs );
(10) (since C++11)
template< class T >
bool operator<( const shared_ptr<T>& lhs, std::nullptr_t rhs );
(11) (since C++11)
template< class T >
bool operator<( std::nullptr_t lhs, const shared_ptr<T>& rhs );
(12) (since C++11)
template< class T >
bool operator<=( const shared_ptr<T>& lhs, std::nullptr_t rhs );
(13) (since C++11)
template< class T >
bool operator<=( std::nullptr_t lhs, const shared_ptr<T>& rhs );
(14) (since C++11)
template< class T >
bool operator>( const shared_ptr<T>& lhs, std::nullptr_t rhs );
(15) (since C++11)
template< class T >
bool operator>( std::nullptr_t lhs, const shared_ptr<T>& rhs );
(16) (since C++11)
template< class T >
bool operator>=( const shared_ptr<T>& lhs, std::nullptr_t rhs );
(17) (since C++11)
template< class T >
bool operator>=( std::nullptr_t lhs, const shared_ptr<T>& rhs );
(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.

Contents

[edit] Parameters

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

[edit] 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 T* and U*
4) rhs < lhs
5) !(rhs < lhs)
6) !(lhs < rhs)
7) !lhs
8) !rhs
9) (bool)lhs
10) (bool)rhs
11) std::less<T*>()(lhs.get(), nullptr)
12) std::less<T*>()(nullptr, rhs.get())
13) nullptr < lhs
14) rhs < nullptr
15) !(nullptr < lhs)
16) !(rhs < nullptr)
17) !(lhs < nullptr)
18) !(nullptr < rhs)

[edit] Exceptions

noexcept specification:  
noexcept
  

[edit] 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.

[edit] Example

[edit] See also

returns a pointer to the managed object
(public member function) [edit]