Here's the recommended study order
for the files in this directory:

php_class_object.php
JSONtoPHP.php
PHPtoJSON.php
JSONarrayToPHParrayOfObjects.php
JSONarrayToPHParrayOfArrays.php
student_data_command_line.php and student_data.json
student_data_web.php and student_data.json
two_quotes1.php and two_quotes.json
two_quotes2.php and two_quotes.json