General PHP Semantics

HrPeanut

Hello!

First of all, sorry if I posted this in the wrong section.. I'm rather new here. :p

I am currently writing a paper about PHP. This includes Syntax, Semantics, and numerous other things like Support for OO and Concurrency. I'm still a little new to PHP as I have only done some things with databases in the past, and I am struggling a little bit with some Semantics. I have, however, Isolated somethings I wish to cover in this section.

I would like to understand the purpose and usage of the '$' symbol in front of every variable. - Is this used for more than just variables?

I would like to understand the purpose and usage of the '->'. In C++, this is used to access elements in a reference. How is it used in PHP?

I would also like an explanation of the '__'. I'm assuming it's for reserved PHP keywords, but I cannot be sure yet.

If anyone could help me out here, it would be greatly appreciated. I've ran the google machine a couple times but no such luck.

Thanks in advance!

dagon

HrPeanut;10895127 wrote:
I would like to understand the purpose and usage of the '$' symbol in front of every variable. - Is this used for more than just variables?

variables

all your other questions are also answered in the manual

NogDog

"->" is used to indicate in OO-PHP that the item on the right is a member of the element on the left, typically $some_object->some_variable or $some_object->a_method(). Also see the scope resolution operator ("::") for a similar operator for referencing static class elements.

The double underscore is used in OO-PHP as the start of the names of certain "magic methods", including __construct for the class constructor.