php创建一个文件夹，其名称以会话开头

I just want to ask if it's possible to create a folder where the name of the folder will start on a session? I tried this: mkdir($_SESSION['user_id'] . "/testing/"); and if it is possible, can you help me how? I'm just a newbie. Thanks!

Yes its possible. You can use mkdir() function with recursive parameters to achieve the goal:

<?php
    session_start();
    $_SESSION['id'] = 123;

    if(isset($_SESSION['id'])) {
        if(!@mkdir($_SESSION['id'] . '/test/', 0777, true)) {
            echo "Dicectory cannot be created";
        };
    }
?>

Read here how it works.

Yes its possible. following is the example.

ini_set('display_errors', 'On'); // display error if occurs any mkdir(realpath(dirname(__FILE__)).'/'.$_SESSION['user_id']."/testing/",0777, true); // realpath(dirname(__FILE__)) gives path to you project directory