Section A.2.  Answers to Chapter 3 Exercises

Here's one way to do it:

    print "Enter some lines, then press Ctrl-D:\n"; # or maybe Ctrl-Z
    @lines = <STDIN>;
    @reverse_lines = reverse @lines;
    print @reverse_lines;

or, even more simply:

    print "Enter some lines, then press Ctrl-D:\n";
    print reverse <STDIN>;

Most Perl programmers would prefer the second one as long as you don't need to keep the list of lines for later use.

Here's one way to do it:

    @names = qw/ fred betty barney dino wilma pebbles bamm-bamm /;
    print "Enter some numbers from 1 to 7, one per line, then press Ctrl-D:\n";
    chomp(@numbers = <STDIN>);
    foreach (@numbers) {
      print "$names[ $_ - 1 ]\n";
    }

We have to subtract one from the index number so the user can count from 1 to 7 even though the array is indexed from 0 to 6. Another way to accomplish this would be to have a dummy item in the @names array, like this:

    @names = qw/ dummy_item fred betty barney dino wilma pebbles bamm-bamm /;

Give yourself extra credit if you checked to make sure that the user's choice of index was in the range 1 to 7.

Here's one way to do it if you want the output all on one line:

    chomp(@lines = <STDIN>);
    @sorted = sort @lines;
    print "@sorted\n";

To get the output on separate lines, do it this way:

    print sort <STDIN>;