PHP基础之预定义接口4——ArrayAccess接口

提供像访问数组一样访问对象的能力的接口。

ArrayAccess { /* 方法 */ abstract public boolean offsetExists ( mixed $offset ) abstract public mixed offsetGet ( mixed $offset ) abstract public void offsetSet ( mixed $offset , mixed $value ) abstract public void offsetUnset ( mixed $offset )}

Example #1 使用范例

<?php class obj implements ArrayAccess {private $container = array();public function __construct() { $this->container = array('one' => 1,'two' => 2,'three' => 3, );}public function offsetSet($offset, $value) { if (is_null($offset)) {$this->container[] = $value; } else {$this->container[$offset] = $value; }}public function offsetExists($offset) { return isset($this->container[$offset]);}public function offsetUnset($offset) { unset($this->container[$offset]);}public function offsetGet($offset) { return isset($this->container[$offset]) ? $this->container[$offset] : null;} } $obj = new obj; var_dump(isset($obj['two'])); var_dump($obj['two']); unset($obj['two']); var_dump(isset($obj['two'])); $obj['two'] = 'A value'; var_dump($obj['two']); $obj[] = ’Append 1’; $obj[] = ’Append 2’; $obj[] = ’Append 3’; print_r($obj);?>

以上例程的输出类似于：

bool(true)int(2)bool(false)string(7) 'A value'obj Object( [container:obj:private] => Array( [one] => 1 [three] => 3 [two] => A value [0] => Append 1 [1] => Append 2 [2] => Append 3))方法列表ArrayAccess::offsetExists — 检查一个偏移位置是否存在ArrayAccess::offsetGet — 获取一个偏移位置的值ArrayAccess::offsetSet — 设置一个偏移位置的值ArrayAccess::offsetUnset — 复位一个偏移位置的值