php 数组写入文件

$fiele = '../data/conf/watermark.php';//指定要写入的文件
    	$param = $this->request->param();
    	$watermark = $param['watermark'];//获取前台传值
$array = "<?php 
    		return ['watermark'=>'".$watermark."']//需要写入的值
    	?>";
    	if(file_put_contents($fiele, $array)){//写入文件
    		$this->success('配置成功', url(''));
    	}else{
    		$this->success('配置失败', url(''));
    	}