How can I execute a PHP code when user leaves/refreshes the page

[vinodxx]

Hello friends,

Have a question here.

I want to execute a particular chunk of PHP code when a user closes the browser window or he refreshes the webpage.

How it can be done in PHP.

Let me explain with an example.

A random number is generated and passed it to a variable(say $x) when a user accesses the webpage for the first time
This variable's value must be preserved till user closes the webpage or she refreshes.

This webpage includes a form whose input is compared against the variable $x.
This form is a self directed one - action = ""

Form code

<form action = "" method = "post">
Number : <input type = "text" name = "name" />
<input type = "submit" />
</form> 

User can try to match the variable $x with "Number" say 5 number of times.

Needs are:
1) The variable $x must not change its value between form submissions.
2) When page refresh/close occurs $x must be destoyed.

How it can be done.

Regards,
Vinod

[BJ Duncan]

Don't know if all requests can be completed, however, holding a value (example, ensuring that $x = 2) for the whole time the user stays online, you need to use $_SESSION[] variable (global variables).

You can use session_destroy() too.

[guido2004]

You can't execute PHP code when the user exits a page. But what you want to do, can be achieved by a combination of session variables and checking if the form has been submitted.
Something like:

<?php
  session_start();
  if (!isset($_POST['submit'])) {
    // if the form hasn't been submitted, initialize the session variables
    $_SESSION['randomnumber'] = // generate random number here;
    $_SESSION['try'] = 1;
  } else {
    // if the form has been submitted, check the number inserted by the user against the random number in the session
    if ($_SESSION['randomnumber'] == $_POST['name']) {
      // do whatever you want to do when the user has guessed the number 
    } else {
      $_SESSION['try']++;
      if ($_SESSION['try'] > 5) {
        // do whatever you want to do when the number of tries has been used
      }
    }
  }
?>
<form action = "" method = "post">
Number : <input type = "text" name = "name" />
<input type = "submit" />
</form>

[joebert]

You can not execute PHP when a visitor leaves the page, but there is something you can do.

Setup PHP that you want executed, and then have Javascript request that PHP page using the "onunload" event of the window in the browser.