_Alignof (since C11)(deprecated in C23), alignof (since C23) operator

From cppreference.com

Queries the alignment requirement of its operand type.

General
Value category
Evaluation order and sequence points
Constant expressions
Implicit conversions
Generic selection (C11)
Constants and literals
Integer constant
Floating constant
Character constant
`true`/`false` (C23)
`nullptr` (C23)
String literal
Compound literal (C99)
Operators
Operator precedence
Member access and indirection
Logical operators
Comparison operators
Arithmetic operators
Assignment operators
Increment and decrement
Function call, comma, conditional operator
sizeof
`_Alignof` (C11*)
Cast operators

Contents