HP 3000 Manuals HP 3000 Manuals
Constant Expressions
Constant expressions are expressions that can be evaluated during
translation rather than run-time.
Syntax
constant-expression ::=
conditional-expression
Description
A constant expression must evaluate to an arithmetic constant expression,
a null pointer constant, an address constant, or an address constant plus
or minus an integral constant expression.
An integral constant expression must involve only integer constants,
enumeration constants, character constants, sizeof expressions, and casts
to integral types. You cannot include the array subscripting ([ ]),
member access (. and ->), and address of (&)operators in integral
constant expressions. An integral constant expression with the value 0,
or such an expression cast to type void *, is called a null pointer
constant. An address constant is a pointer to an object of static
storage duration or to a function designator.
Further, you cannot use a function call, an increment or a decrement
operator, or indirection or assignment operations in a constant
expression.
Constant expressions are usually used for "allocation" type operations.
An example of this is array allocation. The size of an array is given as
a constant expression.
Examples
2 * 2
3 + 3
(-2.5) + 99.8 * 4.5