The C compiler has two built-in functions that return information about a data type's byte alignment and its data type.

The function call __builtin_align(typeID) returns the byte-alignment used for the data type typeID.

The function call __builtin_type(typeID) returns an integral value that describes what kind of data type typeID is. If typeID is an integral or an enumerated type, __builtin_type(typeID) returns 0. If typeID is a floating point type, __builtin_type(typeID) returns 1. If typeID is any other kind of data type, __builtin_type(typeID) returns 2.