Accessing global variables from inside a function in PHP

Question

I want to declare a global variable using PHP and be used inside functions.

I have tried:

$var = "something";
function foo()
{
    echo $var;
}

yet I receive an error stating that the $var is undefined.

How can I solve this?

Answer 1

$var = "something";
function foo()
{
    global $var;
    echo $var;
}

use the term "global" when you need to use variables that were declared outside your function scope.

Answer 2

PHP variables have function scope. I.e., variables inside a function can't be accessed from outside it and global variables can't (by default) be accessed from inside functions. While using the global keyword inside functions to im-/export variables is a solution, you should not do it. Functions should be self-contained; if you need a value inside a function, pass it as a parameter, if the function needs to modify global values, return them from the function.

Example:

function foo($arg)
{
    echo $arg;
}
$var = "something";
foo($var);

Please read: http://php.net/manual/en/language.variables.scope.php