std::shared_lock::operatorbool (3) Linux Manual Page

std::shared_lock<Mutex>::operatorbool – std::shared_lock<Mutex>::operatorbool

Synopsis

explicit operator bool() const noexcept; (since C++14)
Checks whether *this owns a locked mutex or not. Effectively calls owns_lock().

Parameters

(none)

Return value

true if *this has an associated mutex and has acquired shared ownership of it, false otherwise.

See also

          tests whether the lock owns its associated mutex
owns_lock (public member function)