« SplHeap::current SplHeap::insert » PHP Manual SplHeap Extracts a node from top of the heap and sift up SplHeap::extract (PHP 5 >= 5.3.0, PHP 7) SplHeap::extract — Extracts a node from top of the heap and sift up 说明 public SplHeap::extract ( void ) : mixed 参数 此函数没有参数。 返回值 The value of the extracted node. 错误/异常 Throws RuntimeException when the data-structure is empty.