Hash Review/Lab

• Hashes are like arrays, but associate a key and value instead of an index number and value.
• You can get a value by its key, get all values, or get all keys.
• There are more functions in the book that we will not cover: removing keys/values, checking to see if a key exists.
• Why use this?
• Imagine saving keys and values to a file.  You can read these keys and values into a hash, and then do with them as you please.
• You already do use this.  Remember $query->param{'city'} ?
• Now, the Lab:
• Write a Perl script with a hash.
• In the hash, the keys should be names of pets you have had (make some up if you never had pets), and the values should be the type of animal (dog, cat, bird, snake, etc.).
• Print the name and type in an HTML doc.
• Hints:
• The easiest way to start a Perl script is to copy one you already have.
• Start with the four necessary lines: shebang, use CGI, new CGI, and startform.   operators.pl example
• You can assign the hash right in your script, the way we did earlier.
• Use  the while loop .
• And don't forget the URL syntax and  chmod to change the permissions .
• If you get an error, go to oz and type perl -c scriptname.pl to have Perl check the syntax.
• example