php 对象的遍历——迹忆客-ag捕鱼王app官网

php 5 提供了一种定义对象的方法使其可以通过单元列表来遍历，例如用 语句。默认情况下，所有可见属性都将被用于遍历。

示例

简单的对象遍历

 $value) {
           print "$key => $value\n";
       }
    }
}
$class = new myclass();
foreach($class as $key => $value) {
    print "$key => $value\n";
}
echo "\n";
$class->iteratevisible();
?>

以上例程会输出：

var1 => value 1
var2 => value 2
var3 => value 3
myclass::iteratevisible:
var1 => value 1
var2 => value 2
var3 => value 3
protected => protected var
private => private var

如上所示， 遍历了所有其能够访问的可见属性。

更进一步，可以实现 iterator 。可以让对象自行决定如何遍历以及每次遍历时那些值可用。

实现 iterator 接口的对象遍历

var = $array;
        }
    }
    public function rewind() {
        echo "rewinding\n";
        reset($this->var);
    }
    public function current() {
        $var = current($this->var);
        echo "current: $var\n";
        return $var;
    }
    public function key() {
        $var = key($this->var);
        echo "key: $var\n";
        return $var;
    }
    public function next() {
        $var = next($this->var);
        echo "next: $var\n";
        return $var;
    }
    public function valid() {
        $var = $this->current() !== false;
        echo "valid: {$var}\n";
        return $var;
    }
}
$values = array(1,2,3);
$it = new myiterator($values);
foreach ($it as $a => $b) {
    print "$a: $b\n";
}
?>

以上例程会输出：

rewinding
current: 1
valid: 1
current: 1
key: 0
0: 1
next: 2
current: 2
valid: 1
current: 2
key: 1
1: 2
next: 3
current: 3
valid: 1
current: 3
key: 2
2: 3
next:
current:
valid:

可以用 iteratoraggregate 以替代实现所有的 iterator 方法。iteratoraggregate 只需要实现一个方法 iteratoraggregate::getiterator()，其应返回一个实现了 iterator 的类的实例。

通过实现 iteratoraggregate 来遍历对象

items);
    }
    public function add($value) {
        $this->items[$this->count  ] = $value;
    }
}
$coll = new mycollection();
$coll->add('value 1');
$coll->add('value 2');
$coll->add('value 3');
foreach ($coll as $key => $val) {
    echo "key/value: [$key -> $val]\n\n";
}
?>

以上程序会输出：

rewinding
current: value 1
valid: 1
current: value 1
key: 0
key/value: [0 -> value 1]
next: value 2
current: value 2
valid: 1
current: value 2
key: 1
key/value: [1 -> value 2]
next: value 3
current: value 3
valid: 1
current: value 3
key: 2
key/value: [2 -> value 3]
next:
current:
valid: