What are the differences between $, @, % in Perl variable declaration? [duplicate]

Question

Example:

my $some_variable; my @some_variable; my %some_variable; 

I know, @ seems to be for array, $ for primitive, is it totally right? What is % for?

Answer 1

One of the nice things about Perl is that it comes with a built in manual. Type in the following command:

perldoc perlintro 

and take a look at the section Perl variable types. You can also see this on line with the perldoc.perl.org section on Perl variables.

A quick overview:

• $foo is a scalar variable. It can hold a single value which can be a string, numeric, etc.
• @foo is an array. Arrays can hold multiple values. You can access these values using an index. For example $foo[0] is the first element of the array and $foo[1] is the second element of the array, etc. (Arrays usually start with zero).

• %foo is a hash, this is like an array because it can hold more than one value, but hashes are keyed arrays. For example, I have a password hash called %password. This is keyed by the user name and the values are the user's password. For example:

  $password{Fred} = "swordfish"; $password{Betty} = "secret";

  $user = "Fred"; print "The Password for user $user is $password{$user}\n"; #Prints out Swordfish $user = "Betty"; print "The Password for user $user is $password{$user}\n"; #Prints out secret

Note that when you refer to a single value in a hash or array, you use the dollar sign. It's a little confusing for beginners.

I would recommend that you get the Llama Book. The Llama Book is Learning Perl and is an excellent introduction to the language.