Why does PHP not complain when I treat a null value as an array like this?

Question

In PHP, I have error_reporting set to report everything including notices.

Why does the following not throw any notices, errors or anything else?

$my         


        

Answer 1

There are three types which it might be valid to use the array derefence syntax on:

• Arrays
• Strings (to access the character at the given position)
• Object (objects implementing the ArrayAccess interface)

For all other types, PHP just returns the undefined variable.

Array dereference is handled by the FETCH_DIM_R opcode, which uses zend_fetch_dimension_address_read() to fetch the element.

As you can see, there is a special case for NULLs, and a default case, both returning the undefined variable.