Array to String
New notice on array to string conversion

<?php
error_reporting
(-1);
$a = [1,2,3];
echo 
$a;
Output
Array

Careful
<?php
$a 
= [1,2,3];
$b = [3,4,5];
print_r(array_intersect($a,$b));
Output
Array ( [2] => 3 )

<?php
$a 
= [1,2,[3]];
$b = [[3],4,5];
print_r(array_intersect($a,$b));
Output
Array ( [2] => Array ( [0] => 3 ) )

<?php
$a 
= [1,2,[3]];
$b = [[999],4,5];
print_r(array_intersect($a,$b));
Output
Array ( [2] => Array ( [0] => 3 ) )

<?php
$a 
= [1,2,[3]];
$b = ['Array',4,5];
print_r(array_intersect($a,$b));
Output
Array ( [2] => Array ( [0] => 3 ) )