HP C A.06.05 Reference Manual

Data Types and Declarations

Type Qualiﬁers

Chapter 3 47

When a type qualiﬁer is used with a variable typed by a typedef name, the qualiﬁer is

applied without regard to the contents of the typedef. For example:

typedef int *t_ptr_to_int;

volatile t_ptr_to_int vol_ptr_to_int;

In the example above, the type of vol_ptr_to_int is volatile

t_ptr_to_int, which becomes volatile pointer to int. If the type t_ptr_to_int were

substituted directly in the declaration,

volatile int * ptr_to_vol_int;

the type would be pointer to volatile int.

Type qualiﬁers apply to objects, not to types. For example:

typedef int * t;

const t *volatile p;

In the example above, p is a volatile pointer to a const pointer to int. volatile applies to the

object p, while const applies to the object pointed to by p. The declaration of p can also be

written as follows:

t const *volatile p;

If an aggregate variable such as a structure is declared volatile, all members of the aggregate

are also volatile.

If a pointer to a volatile object is converted to a pointer to a non-volatile type, and the object is

referenced by the converted pointer, the behavior is undeﬁned.

int *const const_ptr_to_int Declares a constant pointer to a variable int.

int *volatile vpi, *pi; Declares two pointers: vpi is a volatile pointer to an

int; pi is a pointer to an int.

int const *volatile vpci; Declares a volatile pointer to a constant int.

const *pci; Declares a pointer to a constant int. Since no type

speciﬁer was given, it defaults to int.

Table 3-2 Declarations using const and volatile (Continued)

Declaration Meaning