use strict; my $seq1 = 'aabcdefg'; my $seq2 = 'aabcdefgabcde'; my $ok; # moved up to the file scope sub in_sequence_debug { my $str = shift; $ok = 1; print "Value of OK is $ok\n"; $str =~ m/(.)(.)(??{ print "$1 - $2 "; if ($2 lt $1) { $ok = 0; print "Not Ok\n" } else { print "Ok\n"; }; 0 })/; print "Value of OK is $ok\n"; return $ok; } print "Sequence is ", in_sequence_debug($seq1)?"good":"bad", "\n"; print "-"x40, "\n"; print "Sequence is ", in_sequence_debug($seq2)?"good":"bad", "\n";