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if( $string =~ /^$RE{num}{real}$/ ) { print "Match!\n"; ... else { print "Reject!\n"; }
perl -MRegexp::Common=number -E 'say $RE{num}{real}' (?:(?i)(?:[-+]?)(?:(?=[.]?[0123456789])(?:[0123456789]*)(?:(?:[.])(?:[ +0123456789]{0,}))?)(?:(?:[E])(?:(?:[-+]?)(?:[0123456789]+))|))