php 实现hash表

<?php
/*hash表又称散列表，通过把关键字key经过hash函数映射到hash表中某个位置获取记录。
 * 
 * 存放记录的数组就是hash表
 *  
*/
class hashtable{
	private $buckets;//存储数据的数组
	private $size = 10;//数组长度
	
	public function __construct(){//hash表数组初始化
		$this->buckets = new SplFixedArray($this->size);
	}
	/*=====hash函数=====*/
	private function hashfun($key){
		$strlen = strlen($key);
		$hashval = 0;
		for($i=0;$i<$strlen;$i++){
			$hashval+=ord($key[$i]);
		}
		
		return $hashval%$this->size;
	}
	
	/*=====hash插入操作=====*/
	public function insert($key,$val){
		$index = $this->hashfun($key);
		if(isset($this->buckets[$index])){
			$newnode = new hashnode($key, $val,$this->buckets[$index]);//新增值在头部
		}else{
			$newnode = new hashnode($key, $val);
		}
		$this->buckets[$index] = $newnode;
	}
	
	/*=====hash表取值操作=====*/
	public function find($key){
		$index = $this->hashfun($key);
		$current = $this->buckets[$index];
		
		while(isset($current)){
			if($current->key == $key){
				return $current->value;
			}
			$current = $current->nextnode;
		}
		return NULL;
	}
}

//拉链法解决冲突
class hashnode{
	public $key;
	public $value;
	public $nextnode;
	
	public function __construct($key,$value,$nextnode=NULL){
		$this->key = $key;
		$this->value = $value;
		$this->nextnode = $nextnode;
	}
}

$m = new hashtable();
$m->insert(‘key1‘, ‘value1‘);
$m->insert(‘key12‘, ‘value2‘);
echo $m->find(‘key1‘);
echo $m->find(‘key12‘);


?>