(PHP 5 >= 5.3.0, PHP 7, PHP 8)
SplDoublyLinkedList::bottom — Peeks at the node from the beginning of the doubly linked list
此函数没有参数。
The value of the first node.
Throws RuntimeException when the data-structure is empty.
A note on top() and bottom():
Picture the doubly-linked list (or queue) in the same way that you would a stack.
Say you started with an empty queue, and added five values:
$myList = new SplDoublyLinkedList
$mylist->push(1)
$mylist->push(2)
$mylist->push(3)
$mylist->push(4)
$mylist->push(5)
$mylist->top()
-> 5
$mylist->bottom()
-> 1<?php
/*
* Examples of DoublyLinkedList
*/
$obj = new SplDoublyLinkedList();
// Check wither linked list is empty
if ($obj->isEmpty())
{
echo "Adding nodes to Linked List<br>";
$obj->push(2);
$obj->push(3);
echo "Adding the node at beginning of doubly linked list <br>";
$obj->unshift(10);
}
echo "<br>Our Linked List:";
print_r($obj);
echo "<br>Pick the node from beginning of doubly linked list";
echo $obj->bottom();
?>$a = new SplDoublyLinkedList;
$arr=[1,2,3,4,5,6,7,8,9];
for($i=0;$i<count($arr);$i++){
$a->add($i,$arr[$i]);
}
echo "SplDoublyLinkedList array last/top value " . $a->top() ." \n";
echo "SplDoublyLinkedList array first/top value " . $a->bottom() . " \n\n";
print_r($a);
//Another Example
$spl = new SplDoublyLinkedList;
$spl->push(11);
$spl->push(2);
$spl->push(3);
$spl->push(8);
$spl->push(5);
//array last value
echo $spl->top();
echo PHP_EOL;
//Array first value
echo $spl->bottom();
echo PHP_EOL;
print_r($spl);