unary-expression:
__alignof unary-expression
__alignof ( type-name )
The __alignof operator returns the alignment of its operand, which may be an expression or the parenthesized name of a type. The alignment of the operand is determined according to i5/OS® alignment rules. However, it should not be applied to an expression that has function type or an incomplete type, to the parenthesized name of such a type, or to an expression that designates a bit-field member. The type of the result of this operator is size_t.