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What is the usage of session in php

王林Original: 2020-11-10 11:22:245313browse

The usage of session in php are: 1. Start session, [session_start();]; 2. Store session variables, [$_SESSION['views']=1;]; 3. Terminate session, [ session_destroy();].

Session working mechanism:

Create a unique id (UID) for each visitor and store variables based on this UID . The UID is stored in a cookie or passed through the URL.

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1. Start PHP Session

Before you store user information in the PHP session, A session must first be started.

Note: The session_start() function must be placed before the 100db36a723c770d327fc0aef2ce13b1 tag:

<?php session_start(); ?>

<html>
<body>

</body>
</html>

The above code will register the user's session with the server so that you can start saving user information, and at the same time, it will User sessions are assigned a UID.

2. Store Session Variables

The correct way to store and retrieve session variables is to use PHP $_SESSION variable:

<?php
session_start();
// store session data
$_SESSION[&#39;views&#39;]=1;
?>

<html>
<body>

<?php
//retrieve session data
echo "Pageviews=". $_SESSION[&#39;views&#39;];
?>

</body>
</html>

Output:

Pageviews=1

In In the example below, we create a simple page-view counter. The isset() function detects whether the "views" variable has been set. If the "views" variable is set, we increment the counter. If "views" does not exist, we create the "views" variable and set it to 1:

<?php
session_start();

if(isset($_SESSION[&#39;views&#39;]))
  $_SESSION[&#39;views&#39;]=$_SESSION[&#39;views&#39;]+1;

else
  $_SESSION[&#39;views&#39;]=1;
echo "Views=". $_SESSION[&#39;views&#39;];
?>

3. Terminate Session

If you want to delete some session data, you can use unset() or session_destroy() function.

The unset() function is used to release the specified session variable:

<?php
unset($_SESSION[&#39;views&#39;]);
?>

You can also completely terminate the session through the session_destroy() function:

<?php
session_destroy();
?>

Note: session_destroy() will Reset the session and you will lose all stored session data.

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