<?php
$users = array( 
	"username01" => array(  fullname => "Firstname Lastname",
						  status => "Online"),
	"username02" => array(  fullname => "Firstname Lastname",
						  status => "Offline")
);

$string = "Online";
foreach ($users as $username => $data) {
	$fullname = $data["fullname"];
	$status = $data["status"];
	if($status == $string) { echo "Yes"; } else { echo "No"; }
}
?>

YesNo