global variables or not?

allworknoplay · 05-12-2009, 06:25 PM

Ok so I'm reading a book called PHP 5 Power Programming.

Quote:

PHP does not support global variables like many other programming
languages (except for some special pre-deﬁned variables, which we discuss
later).

He then goes on to say you can access main script variables like so:

$GLOBALS['variable_here'];

I think we all know that. So when someone asks about accessing PHP's global variables, the technical correct answer is NO, PHP does not support it but here's a way to access it within a function....

Is that correct? Kinda confusing....but I get it...

Just want to make sure, because when I take the test, I don't want them asking me, "Does PHP support global variables?"

Then I say, "No".

And the test comes back, "WRONG, you can access it this way: $GLOBALS['variable_here'].."

Which then would mean the test is wrong...

allworknoplay · 05-12-2009, 06:54 PM

Oh I'd like to add, later on when he talks about SUPER GLOBAL ARRAYS, he says this about "global variables..."

Quote:

You don’t have to use the $GLOBALS[] array, which
allows for accessing global variables without having to predeclare them or
using the deprecated globals keyword.

So it sounds like he's stepping ontop of himself. If PHP doesn't support global variables, why is he saying that?

Should he be better off saying, something like:

You don't have to use the $GLOBALS[] array, which allows for accessing your main scripts variables.....

Salathe · 05-12-2009, 08:30 PM

Generally in programming, global variables are those which are accessible in every scope. So when the author says that PHP does not support them, it is true. Take care not to confuse "global variables" with "variables in the global scope": when talking about global variables in PHP that distinction is often blurred.

Global variables (are not supported)

PHP Code:


			
$global = 'my global variable';

function test()

{

  echo $global;

}

test(); // Notice:  Undefined variable: global ...

The quote in the second post is referring only to the superglobal variables. To put it into context, a fuller quote is:

On a language level, it is important to know that you can access these [superglobal] variables anywhere in your script whether function, method, or global scope. You don’t have to use the $GLOBALS[] array, which allows for accessing global variables without having to predeclare them or using the deprecated globals keyword.

allworknoplay · 05-12-2009, 08:42 PM

Quote:

Originally Posted by Salathe

Generally in programming, global variables are those which are accessible in every scope. So when the author says that PHP does not support them, it is true. Take care not to confuse "global variables" with "variables in the global scope": when talking about global variables in PHP that distinction is often blurred.

Global variables (are not supported)

PHP Code:


			
$global = 'my global variable';

function test()

{

  echo $global;

}

test(); // Notice:  Undefined variable: global ...

The quote in the second post is referring only to the superglobal variables. To put it into context, a fuller quote is:

On a language level, it is important to know that you can access these [superglobal] variables anywhere in your script whether function, method, or global scope. You don’t have to use the $GLOBALS[] array, which allows for accessing global variables without having to predeclare them or using the deprecated globals keyword.

Fantastic....understand now.....

I will be looking forward to your book:

Mastering PHP by Salathe

foobarph · 05-13-2009, 10:20 AM

is it also right to say that GLOBAL variables can be set to true/false in the ini file?

Salathe · 05-13-2009, 10:53 AM

I'm not sure if this is what you are asking foobarph but there is an ini directive called register_globals which determines whether or not to register the EGPCS array variables (those within $_ENV, $_GET, $_POST, $_COOKIE and $_SERVER) as normal, global-scope variables (e.g. $_GET['foo'] being available as $foo). This feature is deprecated as of PHP 5.3.0 and removed as of PHP 6.0.0.

Quote:

Mastering PHP by Salathe

Haha.

Killswitch · 05-25-2009, 06:07 AM

To understand what he is talking about, try looking and studying C++. Variables are much the same, but their scope is very different. I'm not too far into learning the lang myself, but from what I've gathered, in C++, variables can be set to the scope of a block of code ( not just a function, a block of code, such as a loop ). Global variables are those started outside of any code blocks ( again, I am pretty sure about this but might have read incorrectly ).

In Php, you can start a variable inside or outside of a block of code and it does not become global. It only becomes global once you implicitly assign it as global.