Not sure what you are needing this to do but the following would preserve clarity as to what was going on. 

#in a loop
s/[A-Z]+/REPLACE/, next;
s/[a-z]+/replace/, next;
s/[A-Z][a-z]+/Replace/, next;

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If its simple letter translation you could of course use tr/// which would keep your cases straight.

In reply to Re: Case-preserving regexp search and replace? by dga
in thread Case-preserving regexp search and replace? by rrwo

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