Here's an easy forward-compatible way to use JSON (json_encode() and json_decode()) in versions of PHP earlier than 5.2.

Download the Services_JSON PEAR package

And then add the following to your custom functions:

if (!function_exists('json_decode')) {
    function json_decode($content, $assoc=false) {
        require_once 'classes/JSON.php';
        if ($assoc) {
            $json = new Services_JSON(SERVICES_JSON_LOOSE_TYPE);
        }
        else {
            $json = new Services_JSON;
        }
        return $json->decode($content);
    }
}

if (!function_exists('json_encode')) {
    function json_encode($content) {
        require_once 'classes/JSON.php';
        $json = new Services_JSON;
        return $json->encode($content);
    }
}


That's it! Your code will continue to work, even when you eventually upgrade to PHP 5.2.