PHP provides an interface for the app to carry parameters and return

<?php
function say(){

$test= $_GET["a"];

if (empty($test)) {
$data["result"]=(string) 2; echo json_encode($data);exit;

}else{
$data["result"]=(string) 1;echo json_encode($data);exit;

}

}
say();
? >

The above introduces the interface provided by PHP for the app to carry parameters and return them, including the content. I hope it will be helpful to friends who are interested in PHP tutorials.