There are several methods for returning data to the frontend in PHP.

1. The echo output: The echo function can be used to directly display data on the front-end page. For example: echo “Hello World”;
2. Outputting using print: The print function can output data to the front-end page. For example: print “Hello World”;
3. Return data in JSON format: Convert data to JSON format using the json_encode function, then use echo to output it. For example:

$data = array("name" => "John", "age" => 30);
echo json_encode($data);

1. A basic XML element
2. in XML format

$xml = new SimpleXMLElement('<root/>');
$xml->addChild('name', 'John');
$xml->addChild('age', 30);
echo $xml->asXML();

1. Output HTML fragments using echo directly. For example: echo “
   

   Hello World

   “;

2. You can set response headers using the header function and then output the data using echo. For example:

header("Content-Type: application/pdf");
echo file_get_contents("example.pdf");

1. title
2. open and view a file

header("Content-Disposition: attachment; filename=example.pdf");
readfile("example.pdf");

These methods can be chosen based on specific needs.