function displayCenter()
{
    include "center.php";
    $obj = new center();
    if (!$obj->view_center()) {
        echo '{"result": 0, "mesage": "Failed to fetch"}';
        return;
    } else {
        echo '{"result":1,"center":[';
        $row = $obj->fetch();
        while ($row) {
            echo json_encode($row);
            $row = $obj->fetch();
            if ($row) {
                echo ",";
            }
        }
        echo "]}";
    }
}
<?php

/**
* 
* @var 
* 
*/
if (isset($_REQUEST['id'])) {
    include "center.php";
    //create object of centers
    $obj = new center();
    $row = $obj->view_center();
    $result = $obj->view_center($id);
    if (!$result) {
        echo '{"result": 0, "message": "Error displaying centers"}';
        return;
    } else {
        echo '{"result": 1, "message": "Displaying centers"}';
        return;
    }
}