//栈（后进先出）
$stack =new SplStack();
$stack->push("data1");
$stack->push("data2");
echo $stack->pop();
echo $stack->pop();
//队列(先进先出)
$queue = new SplQueue();
$queue->enqueue("aaaaaa");
$queue->enqueue("bbbbbb");
echo $queue->dequeue();
echo $queue->dequeue();
//最小堆(从小到大)
$heap = new SplMinHeap();
$heap->insert("555");
$heap->insert("444");
echo $heap->extract();
echo $heap->extract();
//最大堆(从大到小)
$maxHeap = new SplMaxHeap();
$maxHeap->insert(888);
$maxHeap->insert(999);
echo $maxHeap->extract();
echo $maxHeap->extract();
//固定长度的数组
$array = new SplFixedArray(10);
$array[0] = 111;
$array[8] = 888;
var_dump($array);
