How to create a session in PHP with a randomized string?

How do I keep session state of a variable throughout a site?

For example:

A user lands on my website, the string generated is

$string = 'uejsh37rhda283jde86541as'; 

(This string is autogenerated by an xml feed on every page refresh).

Now, everything works so far ok开发者_运维技巧. The problem is when the user clicks on another page on the site, the xml feed creates a new random string.

I know I have to use sessions here, but how exactly?

if(isset($_SESSION[])): 
     ?
else: 
      ?
endif;

Updated code:

if(isset($_SESSION['session'])): 
      $string = $_SESSION['session'];
else: 
      $string = $sessionId;
      $_SESSION['session'] = $string;
endif;

echo $string;

First of all, you need to call session_start() on all pages that access or manipulate session data.

You can do it like this:

session_start();

if (!isset($_SESSION['string'])) {

  $string = makeString();
  $_SESSION['string'] = $string;

}

Try this:

// call session_start() here if session handler is not started yet
if (isset($_SESSION['random-string'])) {
    $string = $_SESSION['random-string'];
} else {
    $string = generateRandomString();
    $_SESSION['random-string'] = $string;
}

if (isset($_SESSION['my_string'])) {
    $string = $_SESSION['my_string'];
}
else {
    $string = generate_random_string();
    $_SESSION['my_string'] = $string;
}
// now do something with $string