PHP登录，存储会话变量

Question

Yo. I'm trying to make a simple login system in PHP and my problem is this: I don't really understand sessions.

Now, when I log a user in, I run session_register("user"); but I don't really understand what I'm up to. Does that session variable contain any identifiable information, so that I for example can get it out via $_SESSION["user"] or will I have to store the username in a separate variable? Thanks.

Answer 1

Let me bring you up to speed.

Call the function session_start(); in the beginning of your script (so it's executed every page call).

This makes sessions active/work for that page automagicly.

From that point on you can simply use the $_SESSION array to set values.

eg

$_SESSION['hello'] = 'world';

The next time the page loads (other request), this wil work/happen:

echo $_SESSION['hello'];  //Echo's 'world'

To simply destroy one variable, unset that one:

unset($_SESSION['hello']);

To destroy the whole session (and alle the variables in it):

session_destroy();

This is all there is about the sessions basics.

Answer 2

The session is able to store any information you might find useful, so putting information in is up to you. To try some things out, try the following and see for yourself:

<?php

    session_start();
    if(isset($_SESSION['foo']))
    {
        echo 'I found something in the session: ' . $_SESSION['foo'];
    }
    else
    {
        echo 'I found nothing, but I will store it now.';
        $_SESSION['foo'] = 'This was a triumph.';
    }

?>

Calling this site the first time should store the information, storing it the second time will print it out.

So yeah, you can basically put anything you like in the session, for instance a username.

Keep in mind, however, that the session dies as soon as the user closes his browser.

Answer 3

$_SESSION['user'] must be set to your user's name/id so that when you try to read it the next time, you'd be able to identify that user. For example:

login: $_SESSION['user'] = some_user_id;

user area: $user = $_SESSION['user']; // extract the user from database, based on the $user variable // do something