Difference between "@" and "$" in Perl

Question

What are the differences between @variable and $variable in Perl?

I have read code with the symbol $ and the symbol @ before a variable name.

For example:

$info = "Caine:Michael:Actor:14, Leafy Drive";
@personal = split(/:/, $info);

What are the difference between a variable containing $ as opposed to @?

Answer 1

It isn't really about the variable, but more about the context how the variable is used. If you put a $ in front of the variable name, then it is used in scalar context, if you have a @ that means you use the variable in list context.

• my @arr; defines variable arr as array
• when you want to access one individual element (that is a scalar context), you have to use $arr[0]

You can find more about Perl contexts here: http://www.perlmonks.org/?node_id=738558

Answer 2

All your knowledge about Perl will be crashed with mountains, when you don't feel context of this language.

As many people, you use in your speech single value (scalars) and many things in a set.

So, the difference between all of them:

i have a cat. $myCatName = 'Snowball';

it jump on bed where sit @allFriends = qw(Fred John David);

And you can count them $count = @allFriends;

but can't count them at all cause list of names not countable: $nameNotCount = (Fred John David);

So, after all:

print $myCatName = 'Snowball';           # scalar
print @allFriends = qw(Fred John David); # array! (countable)
print $count = @allFriends;              # count of elements (cause array)
print $nameNotCount = qw(Fred John David); # last element of list (uncountable)

So, list is not the same, as an array.

Interesting feature is slices where your mind will play a trick with you:

this code is a magic:

my @allFriends = qw(Fred John David);
$anotherFriendComeToParty =qq(Chris);
$allFriends[@allFriends] = $anotherFriendComeToParty; # normal, add to the end of my friends
say  @allFriends;
@allFriends[@allFriends] = $anotherFriendComeToParty; # WHAT?! WAIT?! WHAT HAPPEN? 
say  @allFriends;

so, after all things:

Perl have an interesting feature about context. your $ and @ are sigils, that help Perl know, what you want, not what you really mean.

$ like s, so scalar
@ like a, so array

Answer 3

Variables that start $ are scalars, a single value.

   $name = "david";

Variables that start @ are arrays:

   @names = ("dracula", "frankenstein", "dave");

If you refer to a single value from the array, you use the $

   print "$names[1]"; // will print frankenstein