Perl Cd Bookshelf [Electronic resources] نسخه متنی

A.16. Answer to Chapter 17 Exercises

1. 
   

   Here's one way to do it:

   my $filename = 'path/to/sample_text';
   open FILE, $filename
   or die "Can't open '$filename': $!";
   chomp(my @strings = <FILE>);
   while (1) {
   print "Please enter a pattern: ";
   chomp(my $pattern = <STDIN>);
   last if $pattern =~ /^\s*$/;
   my @matches = eval {
   grep /$pattern/, @strings;
   };
   if ($@) {
   print "Error: $@";
   } else {
   my $count = @matches;
   print "There were $count matching strings:\n",
   map "$_\n", @matches;
   }
   print "\n";
   }

   
   

   This one uses an eval block to trap any failure
   that might occur when using the regular expression. Inside that
   block, a grep pulls the matching strings from the
   list of strings.
   

   Once the eval is finished, we can report either
   the error message or the matching strings. Note that we
   "unchomped" the strings for output by using
   map to add a newline to each string .