As perlman:perlfaq4 says, is would be better to remove leading and trailing whitespace with two steps, not one:

       for ($string) {
         s/^\s+//;
         s/\s+$//;
       }
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So, I'd suggest doing it with two separate supstitutions and the custom-character-class-as-a-string that davorg and John M. Dlugosz suggested. HTH

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