复制代码 代码如下:

class Fibonacci implements Iterator {

private $previous = 1;

private $current = 0;

private $key = 0;

public function current() {

return $this->current;

}

public function key() {

return $this->key;

}

public function next() {

// 关键在这里

// 将当前值保存到 $newprevious

$newprevious = $this->current;

// 将上一个值与当前值的和赋给当前值

$this->current += $this->previous;

// 前一个当前值赋给上一个值

$this->previous = $newprevious;

$this->key++;

}

public function rewind() {

$this->previous = 1;

$this->current = 0;

$this->key = 0;

}

public function valid() {

return true;

}

}

$seq = new Fibonacci;

$i = 0;

foreach ($seq as $f) {

echo "$f ";

if ($i++ === 15) break;

}

程序运行结果：

复制代码 代码如下:

0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610