Access a global variable in a PHP function

It is not working because you have to declare which global variables you'll be accessing:

$data = 'My data';function menugen() {    global $data; // <-- Add this line    echo "[" . $data . "]";}menugen();

Otherwise you can access it as $GLOBALS['data']. See Variable scope.

Even if a little off-topic, I'd suggest you avoid using globals at all and prefer passing as parameters.

You can do one of the following:

<?php    $data = 'My data';    function menugen() {        global $data;        echo "[" . $data . "]";    }    menugen();

Or

<?php    $data = 'My data';    function menugen() {        echo "[" . $GLOBALS['data'] . "]";    }    menugen();

That being said, overuse of globals can lead to some poor code. It is usually better to pass in what you need. For example, instead of referencing a global database object you should pass in a handle to the database and act upon that. This is called dependency injection. It makes your life a lot easier when you implement automated testing (which you should).

Another way to do it:

<?php$data = 'My data';$menugen = function() use ($data) {    echo "[".$data."]";};$menugen();

UPDATE 2020-01-13: requested by Peter Mortensen

As of PHP 5.3.0 we have anonymous functions support that can create closures. A closure can access the variable which is created outside of its scope.

In the example, the closure is able to access $data because it was declared in the use clause.