PHP对象遍历
foreach用法和之前的数组遍历是一样的,只不过这里遍历的key是属性名,value是属性值。在类外部遍历时,只能遍历到public属性的,因为其它的都是受保护的,类外部不可见。
示例:
<?php class HardDiskDrive { public $brand; public $color; public $cpu; public $workState; protected $memory; protected $hardDisk; private $price; public function __construct($brand, $color, $cpu, $workState, $memory, $hardDisk, $price) { $this->brand = $brand; $this->color = $color; $this->cpu = $cpu; $this->workState = $workState; $this->memory = $memory; $this->hardDisk = $hardDisk; $this->price = $price; } } $hardDiskDrive = new HardDiskDrive('希捷', 'silver', 'tencent', 'well', '1T', 'hard', '$456'); foreach ($hardDiskDrive as $property => $value) { var_dump($property, $value); echo '<br>'; } ?>
输出结果为:
string(5) "brand" string(6) "希捷"
string(5) "color" string(6) "silver"
string(3) "cpu" string(7) "tencent"
string(9) "workState" string(4) "well"
如果我们想遍历出对象的所有属性,就需要控制foreach的行为,就需要给类对象,提供更多的功能,需要继承自Iterator的接口:
该接口,实现了foreach需要的每个操作。foreach的执行流程如下图:
看图例中,foreach中有几个关键步骤:5个。
而Iterator迭代器中所要求的实现的5个方法,就是用来帮助foreach,实现在遍历对象时的5个关键步骤:
当foreach去遍历对象时, 如果发现对象实现了Ierator接口, 则执行以上5个步骤时, 不是foreach的默认行为, 而是调用对象的对应方法即可:
示例代码:
<?php class Team implements Iterator { //private $name = 'itbsl'; //private $age = 25; //private $hobby = 'fishing'; private $info = ['itbsl', 25, 'fishing']; public function rewind() { reset($this->info); //重置数组指针 } public function valid() { //如果为null,表示没有元素,返回false //如果不为null,返回true return !is_null(key($this->info)); } public function current() { return current($this->info); } public function key() { return key($this->info); } public function next() { return next($this->info); } } $team = new Team(); foreach ($team as $property => $value) { var_dump($property, $value); echo '<br>'; } ?>
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