##
@x = qw( 5xxx 2xxx 300x 10xx );
@x = sort {$a =~/^d+/ <=> $b =~/^d+/} @x; # WRONG
print "regex sort: @x\n";
####
@x = qw( 5xxx 2xxx 300x 10xx );
@x = sort {my ($y) = $a =~/^(\d+)/;
my ($z) = $b =~/^(\d+)/;
$y <=> $z} @x;
print "regex sort: @x\n";
####
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