A.16 Chapter 17, Database Manipulation

1. Here's one way to do it:

   # program 1:
   dbmopen(%WORDS,"words",0644);
   while (
   
   <>) {
     foreach $word (split(/\W+/)) {
       $WORDS{$word}++;
     }
   }
   dbmclose(%WORDS);

   The first program (the writer) opens a DBM in the current directory called words , creating files named words.dir and words.pag . The while loop grabs each line using the diamond operator. This line is split apart using the split operator, with a delimiter of /\W+/ , meaning nonword characters. Each word is then counted into the DBM array, using the foreach statement to step through the words.

   # program 2:
   dbmopen(%WORDS,"words",undef);
   foreach $word (sort { $WORDS{$b} 
   
   <=> $WORDS{$a} } keys %WORDS) {
     print "$word $WORDS{$word}\n";
   }
   dbmclose(%WORDS);

   The second program opens a DBM in the current directory called words . That complicated looking foreach line does most of the dirty work. The value of $word each time through the loop will be the next element of a list. The list is the sorted keys from %WORDS , sorted by their values (the count) in descending order. For each word in the list, we print the word and the number of times the word has occurred.