HP 3000 Manuals HP 3000 Manuals
Declarations
A declaration specifies the attributes of an identifier or a set of
identifiers.
Syntax
declaration ::=
declaration-specifiers [init-declarator-list] ;
declaration-specifiers ::=
storage-class-specifier [declaration-specifiers]
type-specifier [declaration-specifiers]
type-qualifier [declaration-specifiers]
init-declarator-list ::=
init-declarator
init-declarator-list , init-declarator
init-declarator ::=
declarator
declarator = initializer
Description
Making a declaration does not necessarily reserve storage for the
identifiers declared. For example, the declaration of an external data
object provides the compiler with the attributes of the object, but the
actual storage is allocated in another translation unit.
A declaration consists of a sequence of specifiers that indicate the
linkage, storage duration, and the type of the entities that the
declarators denote.
You can declare and initialize objects at the same time using
the init-declarator-list syntax. The init-declarator-list is a
comma-separated sequence of declarators, each of which may have an
initializer.
Function definitions have a slightly different syntax as discussed in
"Function Declarators" later in this chapter. Also, note that it is
often valid to define a tag (struct, union, or enum) without actually
declaring any objects.
Examples
Valid Declarations:
extern int pressure [ ]; /* size will be declared elsewhere */
extern int lines = 66, pages; /* declares two variables,
initializes the first one */
static char private_func (float); /* a function taking a float,
returning a char, not known
outside this unit */
const float pi = 3.14; /* a constant float, initialized */
const float *const pi_ptr = π /* a constant pointer to a constant
float, initialized with an
address constant */
static j1, j2, j3; /* initialized to zero by default */
typedef struct
{double real, imaginary;} Complex; /* declares a type name */
Complex impedance = {47000}; /* second member defaults to zero */
enum color {red=1, green, blue}; /* declares an enumeration tag and
three constants */
int const short static volatile signed
really_Strange = {sizeof '\?'}; /* pretty mixed up */
Invalid Declarations:
int ; /* no identifier */
; /* no identifier */
int i; j; /* no specifiers for j */