Re: char substitution without regexes

[ikegami]

Awww, jwkrahn beat me to it. Here's one that doesn't use tr/// either:

my %complement = ( a t g c );
%complement = ( %complement, reverse %complement );

print map $complement{$_}, reverse split //, $chain;

%hash and $string are awful names, so I changed them.

[jwkrahn]

Yes, but, that uses a regex and the OP said "without regexes".

[ikegami]

It passes a pattern, but it's actually special-cased not to use the regex engine.

Ok, so I did it without thinking.

print map $complement{$_}, reverse unpack '(a)*', $chain;

[jwkrahn]

Now you've got it!   :-)

By the way, which do you think would be more efficient, reversing the list, or reversing the string first?