Indexed Arrays (Lists)
A list is an ordered set of scalar data. List names follow the same basic rules as for scalars. A reference to a list has the form @foo.
List literals
List literals consist of comma-separated values enclosed in parentheses:
(1,2,3)
(“foo”,4.5)A range can be represented using a list constructor function (such as “..”):
(1..9) = (1,2,3,4,5,6,7,8,9)
($a..$b) = ($a, $a+1, … , $b-1,$b)In the case of string values, it can be convenient to use the “quote-word” syntax
@a = (“fred”,”barney”,”betty”,”wilma”);
@a = qw( fred barney betty wilma );Accessing List Elements
List elements are subscripted by sequential integers, beginning with 0
$foo[5] is the sixth element of @foo
The special variable $#foo provides the index value of the last element of @foo.
A subset of elements from a list is called a slice.
@foo[0,1] is the same as
($foo[0],$foo[1])You can also access slices of list literals:
@foo = (qw( fred barney betty wilma ))[2,3]List operators and functions
Many list-processing functions operate on the paradigm in which the list is a stack. The highest subscript end of the list is the “top,” and the lowest is the bottom.
| push | Appends a value to the end of the list push(@mylist,$newvalue) |
| pop | Removes the last element from the list (and returns it) pop(@mylist) |
| shift | Removes the first element from the list (and returns it) shift(@mylist) |
| unshift | Prepends a value to the beginning of the list unshift(@mylist,$newvalue) |
| splice | Inserts elements into a list at an arbitrary position splice(@mylist,$offset,$replace,@newlist) |
The reverse function reverses the order of the elements of a list
@b = reverse(@a);The sort function sorts the elements of its argument as strings in ASCII order. You can also customize the sorting algorithm if you want to do something special.
@x = sort(@y);The chomp function works on lists as well as scalars. When invoked on a list, it removes newlines (record separators) from each element of its argument.