7 Expressions [expr]

7.6 Compound expressions [expr.compound]

7.6.2 Unary expressions [expr.unary]

7.6.2.5 Alignof [expr.alignof]

An alignof expression yields the alignment requirement of its operand type.
The operand shall be a type-id representing a complete object type, or an array thereof, or a reference to one of those types.
The result is a prvalue of type std::size_­t.
[Note
:
An alignof expression is an integral constant expression ([expr.const]).
The type std::size_­t is defined in the standard header <cstddef> ([cstddef.syn], [support.types.layout]).
end note
]
When alignof is applied to a reference type, the result is the alignment of the referenced type.
When alignof is applied to an array type, the result is the alignment of the element type.