Arrays

• A named list
• Dynamically sized
• 0-based index

• Can push or pop an array (the end of the array is treated like the top of a stack)
  

• Prefixed by @ to refer to the entire array or a slice of the array
• Prefixed by $ to refer to an indexed element of the array
• Prefixed by $# to refer to the index number of the last element (0-based)
• When @array_name is used in a scalar context (where a number would usually be used), the resulting value is the number of elements in the array.

@arr       # array
@arr       # array size (when used as a number)

$arr[n]    # element [n]
$#arr      # element number (last element)

@arr            # the entire array
@arr[2]         # a subarray consisting of the element at index [2]
@arr[0, 1, 3]   # a subarray consisting of the elements at indexes [0], [1], and [3]
$arr[3]         # the element at index [3]

@arr + 0        # array length
scalar(@arr)    # array length

my @arr = ('one', 'two');    # Named array (parentheses)
['one', 'two'];              # Reference to an anonymous array (square brackets)
[@arr];                      # Reference to an anonymous copy of the array (square brackets)

Functions

push

push(@array, LIST)

• Adds a list to the end of the array

pop

pop(@array)

• Removes and returns the last element of the array

shift

shift(@array)

• Removes and returns the first element of the array

unshift

unshift(@array, LIST)

• Adds a list to the front of the array

scalar

scalar(@array)

• Returns the number of elements in the array

Examples

if (@arr1 == 5) {    # If there are exactly 5 elements in the array
    statements;
}

my @arr = ("zero", "one", "two");
my @arr2 = @arr[0, 1];                  # Slice: ("zero", "one")

my $arr_ref = ["zero", "one", "two"];   # Reference to an anonymous array (using square brackets instead of parentheses)

my ($a, $b, $c) = @arr;

my @arr = ();                  # Empty array

my $arr_ref = [];              # Reference to an anonymous empty array (using square brackets instead of parentheses)

# Convert an array reference into a formatted string: (one, two, ...)
sub array_to_string {
    my $arr_ref = shift;
    return '(' . join(", ", @$arr_ref) . ')';
}

# Sample use
my @arr = ("one", "two", "three");
print array_to_string(\@arr);                        # Pass a reference to the array

print array_to_string( ["one", "two", "three"] );    # Pass a reference to an anonymous array (square brackets)
print array_to_string( [@arr] );                     # Pass a reference to an anonymous copy of the array