function affiche_var($nom)
{
global $$nom;
echo '$'.$nom.' = ';var_dump($$nom); echo'<br />';
}

$user = new stdClass();
$user->firstname = 'yvan';
$user->gender = 'male';
$user->address = array('postcode' => 75000, 'country' => 'france');
$user->admin = false;

$logged = false;

$total = 45;

affiche_var('user');
affiche_var('logged');
affiche_var('total');
affiche_var('azerty');

$user = object(stdClass)#1 (4) { ["firstname"]=> string(4) "yvan" ["gender"]=> string(4) "male" ["address"]=> array(2) { ["postcode"]=> int(75000) ["country"]=> string(6) "france" } ["admin"]=> bool(false) }
$logged = bool(false)
$total = int(45)
$azerty = NULL

function dump($var) {
   echo '%X = %Y'; // avec %X le nom de la variable et %Y sa valeur (%X étant le mécanisme que je n'arrive pas à trouver)
}

$user = new stdClass();
$user->firstname = 'yvan';
$user->gender = 'male';
$user->address = array('postcode' => 75000, 'country' => 'france');
$user->admin = false;

dump($user) // doit afficher $user = object(stdClass)#1 {...}

$logged = false;
dump($logged) // doit afficher $logged = false

$total = 45;
dump($total) // doit afficher $total = 45

<?php
$firstname = 'john';
echo '$firstname = '.$firstname;
?> 

<?php
function affiche_var($nom)
{
global $$nom;
echo '$'.$nom.' = '.$$nom.'<br />';
}

$firstname = 'john';

affiche_var('firstname');// Affiche $firstname = john
?>

$firstname = 'john';
dump($firstname) // echo '$firstname = john'

$firstname = 'yvan';
echo getVarName($firstname); // firstname est affiché