You almost surely don't have to think about this problem in terms of chr() (unless you really wanted to). Perl simplifies this task so much that I was initially not sure how to respond. Your question is incomplete. What data are you searching? What did you want to do with it? What are the additional rules for what you call a "word"?

C:\stuff>  perl -ne "print if /\b(foo)\b/"  < input.txt  > matching.tx
+t
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