Learning Perl, 7th Edition

Appendix A. Exercise Answers

This appendix contains the answers to the exercises that appear throughout the book.

Answers to Chapter 1 Exercises

1. This exercise is easy since we already gave you the program. Your job was to make it work:

   print "Hello, world!\n";

   If you have v5.10 or later, you can try say:

   use v5.10;
   say "Hello, world!";

   If you want to try it from the command line without creating a file, you can specify your program on the command line with the -e switch:

   $ perl -e 'print "Hello, World\n"'

   There’s another switch, -l, that automatically adds the newline for you:

   $ perl -le 'print "Hello, World"'

   The quoting on Windows in command.exe (or cmd.exe) needs the double quotes on the outside, so you switch them:

   C:> perl -le "print 'Hello, World'"

   You can save yourself some headaches with quoting by using the generalized quotes inside the shell quoting:

   C:> perl -le "print q(Hello, World)"

   With v5.10 and later, you can use the -E switch to enable new features. That allows you to use say:

   $ perl -E 'say q(Hello, World)'

   We didn’t expect you to try this on the command line because we didn’t tell you about that yet. Still, it’s another way to do it. See perlrun for a complete listing of command-line switches and features.

2. The perldoc command should come with your perl, so you should be able to run it directly. If you can’t find perldoc, you may have to install another package on your system. Ubuntu, for instance, puts it in the perl-doc package.

3. This program is easy too, as long as you got the ...