PHP迭代器实现斐波纳契数列的函数_php实例

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：

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