PHP explode() and implode() can be used to split string into array or join the array elements as string.
date(“format”, timestamp) Returns a string formatted according to the given format string using the given integer timestamp or the current time if no timestamp is given.
If you are writing a code, it is always a good habit to leave comments within your code for later review or for other programmers to see it. In PHP you can leave comments in three different ways, have a look.
You can use FPDF library to easily create PDF file for your project. It’s a free alternative to other commercial PDF generators. It comes with many features too, which you can use to create a wonderful looking PDF files. FPDF is not an PHP extension, just include the class file in your project and you are ready to go, it works with both PHP 4 and PHP 5.