I think to make this work we need to add another line at the end to tell it what to do with the last of the string that is less than $wrap. 
sub wrap {
    my ($s, $wrap) = @_;
    my (@lines, $line);
    
    while (length $s > $wrap) {
        ### Take one extra character so we can see if
        ### we're wrapping inside a word or not
        $line = substr($s, 0, $wrap+1);
        $line =~ s/\s+(\S*)$//;
        push @lines, $line;

        ### Add any word fragments back on
        $s = $1 . substr($s, $wrap);
        $s =~ s/^\s+//;
    }
    push @lines, $s;  ##  Adds the the last of the $s string to @lines
    return join "\n", @lines;
}

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In reply to Re^2: Word wrapping using a regex. by Additude
in thread Word wrapping using a regex. by Anonymous Monk

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