Variables

时间：2008-01-17 来源：xiaoaizhen

$var	a simple scalar variable.
$var[28]	29th element of array @var.
$p = \@var	now $p is a reference to array @var.
$$p[28]	29th element of array referenced by $p. Also, $p->[28].
$var[-1]	last element of array @var.
$var[$i][$j]	$jth element of the $ith element of array @var.
$var{'Feb'}	one value from hash (associative array) %var.
$p = \%var	now $p is a reference to hash %var.
$$p{'Feb'}	a value from hash referenced by $p. Also, $p->{'Feb'}.
$#var	last index of array @var.
@var	the entire array; in a scalar context, the number of elements in the array.
@var[3,4,5]	a slice of array @var.
@var{'a','b'}	a slice of %var; same as ($var{'a'},$var{'b'}).
%var	the entire hash; in a scalar context, true if the hash has elements.
$var{'a',1,...}	emulates a multidimensional array.
('a'...'z')[4,7,9]	a slice of an array literal.
PKG::VAR	a variable from a package, e.g., $pkg::var, @pkg::ary.
\OBJECT	reference to an object, e.g., \$var, \%hash.
*NAME	refers to all objects represented by NAME. n1 = n2 makes n1 an alias for n2. *n1 = $n2 makes $n1 an alias for $n2.

You can always use a {BLOCK} returning the right type of reference instead of the variable identifier, e.g., ${...}, &{...}. $$p is just a shorthand for ${$p}.

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