-- Perl 5.8.6 documentation --
ref
  • ref EXPR
  • ref
  • Returns a non-empty string if EXPR is a reference, the empty string otherwise. If EXPR is not specified, $_ will be used. The value returned depends on the type of thing the reference is a reference to. Builtin types include:

        SCALAR
        ARRAY
        HASH
        CODE
        REF
        GLOB
        LVALUE

    If the referenced object has been blessed into a package, then that package name is returned instead. You can think of ref as a typeof operator.

        if (ref($r) eq "HASH") {
    	print "r is a reference to a hash.\n";
        }
        unless (ref($r)) {
    	print "r is not a reference at all.\n";
        }
        if (UNIVERSAL::isa($r, "HASH")) {  # for subclassing
    	print "r is a reference to something that isa hash.\n";
        }

    See also perlref.