saveform.php

<?php
// Read in the existing comments
$contents =  utf8_encode(file_get_contents("comments.json"));

// Convert from JSON format to an Array
$commentrecords = json_decode($contents, true);

//Add a new array item for the newly posted comment
$commentrecords[] = array("name" => strip_tags($_POST["name"]), "comment" => strip_tags($_POST["comment"]));

//Save everything back to the file
file_put_contents("comments.json", json_encode($commentrecords, JSON_PRETTY_PRINT), LOCK_EX); 

//Redirect back to the form
header("Location: project.php");
die();

?>