问题
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?
回答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.
回答2:
$ is for scalars, @ is for arrays, and % is for hashes. See the Variable Types section of the the docs for more information.
回答3:
$ is scalar, @ is array, and % is hash.
回答4:
$var denotes a single-valued scalar variable
@var denotes an array
%var denotes an associative array or hash (they are both the same)
来源：https://stackoverflow.com/questions/5553898/what-are-the-differences-between-in-perl-variable-declaration