Cookies in php

• What is a Cookie?
  A cookie is often used to identify a user. A cookie is a small file that the server embeds on the user's computer. Each time the same computer requests a page with a browser, it will send the cookie too. With PHP, you can both create and retrieve cookie values.


• How to Create a Cookie?
  

  Syntax:

  setcookie(name, value, expire, path, domain);
  

  Example -

  setcookie("user", "Alex Porter", time()+3600);


• How to Retrieve a Cookie Value?
  The PHP $_COOKIE variable is used to retrieve a cookie value.
  

  Example -

  // Print a cookie
  echo $_COOKIE["user"];
  // A way to view all cookies
  print_r($_COOKIE);


• How to Delete a Cookie?
  When deleting a cookie you should assure that the expiration date is in the past.
  // set the expiration date to one hour ago
  setcookie("user", "", time()-3600);
• 
  

  • Checking for Cookie Support from PHP

    
      < ? php
         if(!isset($_GET['testcookie']))
         {
           setcookie("testcookie", "test value");
           header("Location: {$_SERVER["PHP_SELF"]}?testcookie=1");
           exit;
         }
         else
         {
           if(isset($_COOKIE['testcookie']))
           {
             setcookie("testcookie");
             echo "You have cookies enabled";
           }
           else
           {
             echo "You do not support cookies!";
           }
         }
      ? >

  • Reading all cookie values

    
      < ? php
         foreach ($_COOKIE as $cookie_name => $cookie_value)
         {
           print "$cookie_name = $cookie_value
    ";
         }
      ? >

  • Still Logged In with cookie

    
      < ? php
         $auth = $_COOKIE['auth'];
         header( "Cache-Control:no-cache" );
         if( ! $auth == "ok" )
         {
           header("Location:login.php" );
           exit();
         }
      ? >

  • Printing a cookie value

    
       < ? php
         print 'Hello, ' . $_COOKIE['userid'];
       ?>

  • Reading a cookie value

    
      < ? php
        if (isset($_COOKIE['flavor']))
        {
           print "You ate a {$_COOKIE['flavor']} cookie.";
        }
      ?>