$array = array();
$array = []; 
$array['foo'] = 'bar';
$array['bar'] = 'foo';

echo($array['foo']); 
echo($array['moo']); 


$array2 = array('fruit' => 'apple',
                'price' => 12.96,
                'colour' => 'green');


$array2 = ['fruit' => 'apple',
                'price' => 12.96,
                'colour' => 'green'];


echo(isset($array['foo'])); 
echo(array_key_exists('foo', $array));