json_encode < PHP
The json_encode function takes a PHP array or object and returns a string of JSON.
$numbers = array('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5);
$numbers_encoded = json_encode($numbers);
echo $numbers_encoded;
// {"a":1,"b":2,"c":3,"d":4,"e":5}