The (*F) operator was introduced with 5.10. Prior to that, (?!) can be used.
>perl wMstrict le
"for my $n (4 .. 9) {
my $str = qq{I have 5 apples, $n oranges, and 8 limes.};
print qq{'$str'};
next unless $str =~ m{
(\d+) \s+ apples \D+
(\d+) \s+ oranges \D+
(\d+) \s+ limes
(?(?{ $1 < $2 && $2 < $3 })  (*F) )
}xms;
print qq{'$2'};
}
"
'I have 5 apples, 4 oranges, and 8 limes.'
'I have 5 apples, 5 oranges, and 8 limes.'
'I have 5 apples, 6 oranges, and 8 limes.'
'6'
'I have 5 apples, 7 oranges, and 8 limes.'
'7'
'I have 5 apples, 8 oranges, and 8 limes.'
'I have 5 apples, 9 oranges, and 8 limes.'
