(PHP 7 >= 7.4.0)
FFI::addr — Creates an unmanaged pointer to C data
   Creates an unmanaged pointer to the C data represented by the given
   FFI\CData. The source ptr must survive the
   resulting pointer. This function is mainly useful to pass arguments to C functions by pointer.
  
ptrThe handle of the pointer to a C data structure.
Returns the freshly created FFI\CData object.