How to display json array data in PHP code example

Example 1: php return json data

header('Content-Type: application/json'); 

$colors = array("red","blue","green");
echo json_encode($colors);

Example 2: how to get data from json array in php

$data = json_decode($json);

Example 3: return json in php

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