Here's how your for line reads, assuming you have 9 things in your array:

for ( $a=0;$a 9; $a++)
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I'll leave it up to you to figure out what the missing character is =)

Also, note that your substitution will only replace the first occurrence of each code in each line. You'll need to add the /g modifier if you want to change all the matches.

Also, note that $a is a special variable in Perl, it's a package global used by sort subroutines and it's not usually the best choice for a throwaway.

If not P, what? Q maybe?
"Sidney Morgenbesser"