Question

I have the following code that makes a PDO object, which is at the end of core.php:

try {
    $dbh = new PDO("mysql:host=localhost;dbname=xxx", 'xxx', 'xxx');
} catch (PDOException $exc) {
    header(HTTP_500_HEADER);
    die('Database connection failure');
}

In index.php, which is in a directory above it, it includes fine and I am able to access it. I am not accessing $dbh from a function.

However, when I try to access it from inside a function like this (this time it’s a different file in a different dir):

require_once '../_/core.php';
var_dump($dbh);

$show_html = true;
$rm = $_SERVER['REQUEST_METHOD'];

function login_check() {
    var_dump($dbh);
}

The first var dump shows it is a PDO object, but the second shows it’s null.

Answer 1

If you want to access a global variable in a function you need to define it (here $dbh) as global inside the function (also see the manual):

function login_check() {
    global $dbh;
    var_dump($dbh);
}