Description:
------------
The 2nd example for array_filter shows its usage without a callback to filter empty array elements.

The example does not include entries for zero values, which could cause issues for newer developers who aren't familiar with PHP's type system.

I would suggest updating the example to include zero values:

$entry = array(
             0 => 'foo',
             1 => false,
             2 => -1,
             3 => null,
             4 => '',
             5 => '0',
             6 => 0,
          );

print_r(array_filter($entry));