public function testLen()
{
$l = new DoublyLinkedList();
$this->assertEquals(0, $l->len());
// pushFront and pushBack will increases list's length.
$e1 = $l->pushFront(1);
$e2 = $l->pushFront(2);
$e3 = $l->pushBack(3);
$e4 = $l->pushBack('four');
$this->assertEquals(4, $l->len());
// remove will decreases list's length.
$l->remove($e1);
$this->assertEquals(3, $l->len());
// remove inexistsent element won't decrease list's length.
$l->remove($e1);
$this->assertEquals(3, $l->len());
$l->remove($e2);
$l->remove($e3);
$l->remove($e4);
$this->assertEquals(0, $l->len());
}
if ($node == NULL) {
//if $node points to NULL
echo "Linked List is empty";
return NULL;
}
while ($node->next != NULL) {
echo "Node value is " . $node->value . "<br />";
$node = $node->next;
//now have $node point to where $node->next is pointing to
}
echo "Node value is " . $node->value . "<br />";
//have it print the last node value
}
}
$dll = new DoublyLinkedList();
//creates a new instance of the doubly linked list
$dll->add(5);
//should add a new node with the value of 5
$dll->add(7);
//should add a new node with the value of 7
$dll->add(10);
$dll->removeAllNodesWithValueOf(7);
//should remove all nodes with value of 7
$dll->remove(1);
//removes node of position 1
$dll->add(3);
//should add a new node with the value of 3
$dll->insert(1, 100);
//insert a new node of value 100 in the position 1
$dll->printValues();
//should print all the values in the doubly linked list
