while(<FILE>){
   if (/$pattern/ox)  #options to allow whitespace in the pattern, and to prevent the compiler from recalculating it at every run)

     $chars{$&}++; #$& is the part of the string that actually matches the pattern
}

foreach (keys %chars){
  print "unpack 'U*', $_ matched $chars{$_} times.\n";

#I am unsure on the "unpack"