printing json from php code example

Example 1: php echo json

<?php
$data = ['name' => 'John', 'age' => 35];
header('Content-type: Application/json');
echo json_encode($data);

Example 2: return json in php

//code igniter
$query="qry";
$query = $this->db->query($query);
$res=$query->result();
return json_encode($res);