Global Variables

The php manual leads me to believe that making a variable available to all the functions and includes in my script as easy as:

global $a = "foo";

function some_function(){
  echo $a;
}

but in practice this fails. The manual also says that this should work:

$a = "foo";
function some_function(){
  echo $a;
}

but, it doesn't. The only way I've gotten it to work thusfar is:

$a = "foo";
function some_function($a){
  echo $a;
}

Any thoughts?

global

should be inside the function :

function something()
{
    global $a;
    echo $a;
}

[edit] but it's a better idea to pass the variable in the first place, i.e. your third example.[/edit]

Variable scoping in PHP is upside-down from the way it's handled in most similar (C-like) languages. Inside a function, NOTHING is visible unless:

(a) you declare it as a global (i.e., external) value. This makes sense if you think of the declaration as an "import" statement.

(b) you pass it as an argument.