limit curl requests per user - php

Question

I searched all over, but have not seen anything related to this question. I have a curl script that obtains a random generated string of 10 characters from a website. I have received permission from the website owner to fetch this data and display it on my blog. My question is this when a user comes to my website it displays the string and if they refresh the page it will display a new string. How can I limit one string per user so that they cannot refresh over and over to obtain multiple strings?
Here is an example curl upon which my code is based:
$url = "http://m.www.yahoo.com/";
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$output = curl_exec($ch);
preg_match('/<dl class="markets clearfix strong small">(.*)<\/dl>/is', $output, $matches);
echo $matches[0];
curl_close($ch);

Answer 1

maybe you can use session variable to check if the user has already got a string.
function startSession(){
$id = session_id();
if ($id != '')
session_write_close();
if (isset($_COOKIE['PHPSESSID']) && $id != $_COOKIE['PHPSESSID']) {
session_write_close();
session_id($_COOKIE['PHPSESSID']);
}
session_start();
}
//Start your sessions
startSession();
if (!$_SESSION['UserGotAString']) {
echo "Some Error msg"
return;
}
session_write_close();
//Request to Yahoo and regex match comes here..
// Start a session
startSession();
$_SESSION['UserGotAString'] = true
echo $matches[0];
session_write_close();
Im not sure if this a good method. Also if you want to reset the session variable base on timer check this link
Set timeout in php