Question

For example, return the part of the string that is after the last x in axxxghdfx445 (should return 445).

Answer 1

my($substr) = $string =~ /.*x(.*)/;

From perldoc perlre:

By default, a quantified subpattern is “greedy”, that is, it will match
as many times as possible (given a particular starting location) while
still allowing the rest of the pattern to match.

That’s why .*x will match up to the last occurence of x.