global variables in php not working as expected

Question

I\'m having trouble with global variables in php. I have a $screen var set in one file, which requires another file that calls an initSession() def

Answer 1

It is useless till it is in the function or a class. Global means that you can use a variable in any part of program. So if the global is not contained in the function or a class there is no use of using Global

Answer 2

You need to put "global $screen" in every function that references it, not just at the top of each file.

Answer 3

You must declare a variable as global before define values for it.

Answer 4

If you have a lot of variables you want to access during a task which uses many functions, consider making a 'context' object to hold the stuff:

//We're doing "foo", and we need importantString and relevantObject to do it
$fooContext = new StdClass(); //StdClass is an empty class
$fooContext->importantString = "a very important string";
$fooContext->relevantObject = new RelevantObject();

doFoo($fooContext);

Now just pass this object as a parameter to all the functions. You won't need global variables, and your function signatures stay clean. It's also easy to later replace the empty StdClass with a class that actually has relevant methods in it.

Answer 5

global $foo doesn't mean "make this variable global, so that everyone can use it". global $foo means "within the scope of this function, use the global variable $foo".

I am assuming from your example that each time, you are referring to $screen from within a function. If so you will need to use global $screen in each function.

Answer 6

The global scope spans included and required files, you don't need to use the global keyword unless using the variable from within a function. You could try using the $GLOBALS array instead.