```{index} single: id (Hash::Util::FieldHash) ``` ```{index} single: Hash::Util::FieldHash::id ``` # id The id of a reference: the number a field hash stores it under. ## Synopsis ```perl use Hash::Util::FieldHash qw(id); my $id = id($obj); ``` ## What you get back For a reference, the address of what it points to, as a number - the same value `Scalar::Util::refaddr` gives. The id stays the object's for its lifetime. Anything that is not a reference comes back unchanged, where `refaddr` gives `undef`.