As of PHP 5.4 you can also use short array syntax, which replaces array() with [ ] square brackets.
Example:
The 1st example codes the array function for 2 custom post types named listing and portfolio using array().
array( 'listing','portfolio' );You can now code the array using square brackets like this:
['listing','portfolio'];If you’re learning PHP, at some stage you’ll come across PHP code which codes arrays using square brackets.