Why session_id cannot get the value of session

Set session

<code>     $sid=session_id();
     session('uid',100);</code>

It can be set up successfully here.

Get session

<code>  session_id($sid);
  session_start();
  session('uid');//无法获取值</code>

Reply content:

Set session

<code>     $sid=session_id();
     session('uid',100);</code>

It can be set up successfully here.

Get session

<code>  session_id($sid);
  session_start();
  session('uid');//无法获取值</code>

This is embarrassing
If you want to use session, you first need session_start(), and put it in front of all statements containing session;
Use $_SESSION['name'] = 'session' when setting and modifying;