[nova912]

What does "->" do, and "=&" do... I can't seem to find any documentation on these.

[Patiek]

The "->" that you see is the member selection that will be used for object-oriented code using classes.

Such as:

PHP Code:

<?php

class MyClass

{

    function someFunction()

    {

        echo "Hello World";

    }

}



$object = new MyClass(); // creates object of MyClass

$object->someFunction(); // outputs Hello World

The "=&" is actually a normal = with the & prefixing a variable. Think of it as referring to the memory address of the variable, as opposed to the value itself.

Consider the following: You have a variable $somevar that has been created and assigned to some memory address:

PHP Code:

$somevar = "hello"; 

Now when you go about doing a normal assignment:

PHP Code:

$othervar = $somevar; 

$othervar will equal the value of "hello", but will not be the same as $somevar.

This is illustrated by the code:

PHP Code:

$somevar = "hello";

$othervar = $somevar;

$othervar = "bye";



echo "somevar: " . $somevar . "\n";

echo "othervar: " . $othervar . "\n"; 

The output would be:

Code:

somevar: hello
othervar: bye

Now consider using the "&":

PHP Code:

$somevar = "hello";

$othervar = &$somevar;

$othervar = "bye";



echo "somevar: " . $somevar . "\n";

echo "othervar: " . $othervar . "\n"; 

The output would be:

Code:

somevar: bye
othervar: bye

Notice how the "&" does NOT create a new point in memory but in fact links to the same point as $somevar. Thus, changing $othervar to "bye" will also change $somevar to "bye" and vice versa (actually, they are in fact the same value, but referenced by two different names). Like a person having multiple nicknames, it is the same person, but just referred to in different ways.

[duesi]

Patiek is totally right.

&$somevar is used often to pass a variable by reference to a function,
If you want a function to be able to overwrite the variable (but this ofent leads to bugs which are hard to track).
I use it for example to share a single instance of an object in many other objects:

PHP Code:

//This is an object that can log errors to a logfile

$logger = new logger();



//The Database obejct uses this logger and does not need to 

//create a new instance

$db = new db(&$logger);



//the renderer also

$renderer = new renderer(&$logger); 

Happy Coding!