Basic PHP implementations, opcodes, and internal work

The main purpose of this paper is to investigate how PHP works internally, how variables, arrays, objects etc. are stored in memory. The paper will cover some generated series of operation codes, commonly known as “opcodes”, and why advanced PHP programmers should know, at least, basics of PHP “under-the-hood”. Also, one of the goals is to show how function calls and classes work internal- ly, basic concepts like “is pre-increment or post-in- crement faster” and, as a PHP developer, what you should or should not do in your code.