Learning Perl, Second Edition

3.4. Array Operators and Functions

Array functions and operators act on entire arrays. Some return a list, which can then either be used as a value for another array function, or assigned into an array variable.

3.4.1. Assignment

Probably the most important array operator is the array assignment operator, which gives an array variable a value. It is an equal sign, just like the scalar assignment operator. Perl determines whether the assignment is a scalar assignment or an array assignment by noticing whether the assignment is to a scalar or an array variable. For example:

@fred = (1,2,3); # The fred array gets a three-element literal
@barney = @fred; # now that is copied to @barney

If a scalar value is assigned to an array variable, the scalar value becomes the single element of an array:

@huh = 1; # 1 is promoted to the list (1) automatically

Array variable names may appear in a list literal list. When the value of the list is computed, Perl replaces the names with the current values of the array, like so:

@fred = qw(one two);
@barney = (4,5,@fred,6,7); # @barney becomes 
                           # (4,5,"one","two",6,7)
@barney = (8,@barney);     # puts 8 in front of @barney
@barney = (@barney,"last");# and a "last" at the end
                        # @barney is now (8,4,5,"one","two",6,7,"last")

Note that the inserted array elements are at the same level as the rest of the literal: a list cannot contain another list as an element.^[2]

^[2] Although a list reference is permitted as a list element, it's not really a list as a ...