How to tell apart numeric scalars and string scalars in Perl?

Question

Perl usually converts numeric to string values and vice versa transparently. Yet there must be something which allows e.g. Data::Dumper to discriminate between

Answer 1

One simple solution that wasn't mentioned was Scalar::Util's looks_like_number. Scalar::Util is a core module since 5.7.3 and looks_like_number uses the perlapi to determine if the scalar is numeric.