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How to set & unset session variable in codeigniter ?

  • Last Updated : 07 Jan, 2022

The session class in CodeIgniter allows the user to maintain a user’s “state” and track their activity while browsing the website. The session can be initialized using the library and auto-loaded in the environment using the following command.

$this->load->library('session');

Set the session variable: Session indexes can be assigned using key-value pairs. A particular key can be assigned to a value using the assignment operator. The value may be a string, key, or even an array. 

Syntax:

$_SESSION['key'] = value; 

 

Example 1:

PHP




<?PHP   
  
  // Starting a new session 
  session_start(); 
  
  $_SESSION['id'] = 9 ;
  
  // Check if the session name exists 
  if( isset($_SESSION['id']) ) { 
      echo 'Session id is '.$_SESSION['id'].'<br>'
  
  else
      echo 'Set the session id first '.'<br>'
  
   echo'<br>';
    
  // Modifying the value of session 
  $_SESSION['id'] = -8 ; 
  echo 'New session id is '.$_SESSION['id'].'<br>';     
?> 

Output:

Session id is 9
New session id is -8

The session value can also be assigned using the set_userdata() method in CodeIgniter. This method takes a key as the first argument and the. next is the value to be assigned. 

Syntax:

set_userdata ('key' , value)

Multiple key-value pairs can also be added at the session index in CodeIgniter, indicated by the following code snippet.

Example 2:

PHP




<?php
  
  // Setting multiple key values
  $sess_arr = array('id'=>5, 'name' => 'yash');
    
  // Setting index at logged_in
  $this->session->set_userdata('logged_in', $sess_arr);
  
  // Printing the contents at this index
  print_r($_SESSION['logged_in']);
?>

Output:

Array ( [id] => 5 [name] => yash ) 

Unset the session variable: The session variable can be unset by assigning it to a NULL value. This destroys the value stored at this key value. 

Syntax:

$_SESSION['ey'] = NULL

Example 3:

PHP




<?php   
  
  // Starting a new session 
  session_start(); 
  
  // Setting multiple values 
  $sess_arr = array('id'=>5, 'name' => 'yash');
  
  $_SESSION['logged_in']= $sess_arr;
  echo ('Old session : ');
  print_r ($_SESSION['logged_in']);
  echo '</br>';
  
  // Unsetting the value
  $_SESSION['logged_in']= NULL;
  echo ('New session? : ');
  print_r ($_SESSION['logged_in']);
?> 

Output:

Old session : Array ( [id] => 5 [name] => yash )
New session? :


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