Array
(
[0] => Array
(
[adArea_area_id] => 1
)

[1] => Array
(
[adArea_area_id] => 2
)

)

Array
(
[0] => Array
(
[area_id] => 1
[area_name] => Home
)

[1] => Array
(
[area_id] => 2
[area_name] => Espace Perso
)

[2] => Array
(
[area_id] => 3
[area_name] => Création de compte
)

[3] => Array
(
[area_id] => 4
[area_name] => Achats
)

[4] => Array
(
[area_id] => 5
[area_name] => Création d'annonce
)

[5] => Array
(
[area_id] => 6
[area_name] => Affichage d'annonce
)

[6] => Array
(
[area_id] => 7
[area_name] => Recherche
)

[7] => Array
(
[area_id] => 8
[area_name] => Pages classiques
)

)

foreach($areas as $key => $area) {
					if(in_array($area['area_id'], $adAreas)) {
						$checked = 'checked="checked"';
					}
					else
						$checked = '';
					echo '<td width="20%"><input type="checkbox" name="ad_areas[]" value="'.$area['area_id'].'" style="vertical-align:middle;" '.$checked.' /> '.$area['area_name'].'</td>';
					if($count % 4 == 0)
						echo "</tr>\n</tr>";
					$count++;
				}

<?php
function recursive_in_array($needle, $haystack) {
    foreach ($haystack as $stalk) {
        if ($needle === $stalk || (is_array($stalk) && recursive_in_array($needle, $stalk))) {
            return true;
        }
    }
    return false;
}
?>