Constant Expressions

Constant expressions may never contain (except as an operand to the sizeof operator):

• Assignment operators
• Increment or decrement operators
• Comma operators
• Function calls

Integral constant expressions

... are used in case expressions, to specify array bounds, to specify the size of a bit-field and as enumerator constants.

They may contain:

• Integral constants
• Enum constants
• Character constants
• sizeof expressions
• Floating constants cast to an integer type

... but may not contain (except as an argument to the sizeof operator):

• Arrays
• * operator
• & operator
• Structure member operations

Constant expressions in #if and #elif statements

... are integral constant expressions, but may not contain:

• sizeof expressions
• enumeration constants
• casts

Initializer constant expressions

... may contain any integer constant expression but can also include:

• Any type of constant
• & applied to external or static objects
• & applied to external or static arrays subscripted with a constant expression
• & applied implicitly by including a function name or an unsubscripted array name.

Index