std::experimental::observer_ptr::operator bool
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                    < cpp | experimental | observer ptr
                    
                                                            
                    | constexpr explicit operator bool() const; | (library fundamentals TS v2) | |
Checks whether *this has an associated watched object, i.e. whether get() != nullptr.
Parameters
(none)
Return value
true if *this has an associated watched object, false otherwise.
Exceptions
noexcept specification:  
noexcept
  Example
| This section is incomplete Reason: no example | 
See also
| returns a pointer to the watched object (public member function) |