You need to surround $file = readdir($handle) with parentheses.
Here you go:
$log_directory = 'your_dir_name_here';
$results_array = array();
if (is_dir($log_directory))
{
if ($handle = opendir($log_directory))
{
//Notice the parentheses I added:
while(($file = readdir($handle)) !== FALSE)
{
$results_array[] = $file;
}
closedir($handle);
}
}
//Output findings
foreach($results_array as $value)
{
echo $value . '<br />';
}