php将数据存储到file文件

<meta charset="UTF-8">
<?php
//接收表单数据
$user = $_REQUEST["user"];
$pass = $_REQUEST["pass"];
$phone = $_REQUEST["phone"];
$address = $_REQUEST["address"];
$date = date("H:i,S H Y");
$DOCUMENT_ROOT = $_SERVER["DOCUMENT_ROOT"];

echo "用户：".$user."<br>密码：".$pass."<br>手机：".$phone."<br>地址：".$address."<br>日期：".$date."<br>路径：".$DOCUMENT_ROOT;

//将数据写入file文件3步骤:创建打开--写入数据--保存关闭
//1.打开文件并选择模式（只读、只写、读写）
$fp = fopen("$DOCUMENT_ROOT/phpPro/src/data/reg.txt","ab");
if(!$fp){
    echo "error!";
    exit;
}
//写入数据
$outputstring = $user.$pass.$phone.$address.$date."
";
fwrite($fp,$outputstring,strlen($outputstring));
flock($fp,LOCK_UN);
fclose($fp);
echo "<br>数据写入成功<br>";

//读文件
$fp = fopen("$DOCUMENT_ROOT/phpPro/src/data/reg.txt","rb");
if(!$fp){
    echo "error!";
    exit;
}
while(!feof($fp)){
    $order = fgets($fp,999);
    echo $order."<br>";
}
?>