How To Retrieve the Session ID of the Current Session? - PHP Script Tips - Understanding and Using Sessions

Normally, you don't need to know the session ID of the current session. But if you are interested to know the session ID created by the PHP engine, there are two ways to get it:

• Calling session() function. It will return the session ID value.
• Using built-in constant SID. It will contains a string of session ID name and value.

The tutorial PHP script below shows you how to retrieve the session ID in two ways:

<?php
  session_start();
  print("<html><pre>");

  $sid = session_id();
  print("Session ID returned by session_id(): ".$sid."\n");
  $sid = SID;
  print("Session ID returned by SID: ".$sid."\n");

  $myLogin = $_SESSION["MyLogin"];
  print("Value of MyLogin has been retrieved: ".$myLogin."\n");
  $myColor = $_SESSION["MyColor"];
  print("Value of MyColor has been retrieved: ".$myColor."\n");

  print("</pre></html>\n");
?>

You need to save this script to your Web server as next_page.php. Now visit first_page.php and click the "Next Page" hyper like, you will get something like this:

Session ID returned by session_id(): rfnq17ui6c7g6pjbtc46n0vi97
Session ID returned by SID: PHPSESSID=rfnq17ui6c7g6pjbtc46n0vi97
Value of MyLogin has been retrieved: FYICenter
Value of MyColor has been retrieved: Blue

Now you know that the session ID created by the PHP engine is 26 characters long with alphanumeric characters only.