Mikroelektronika MIKROE-738 Datenbogen
226
mikoC PRO for PIC32
MikroElektronika
Type Qualifiers
The type qualifiers
const
and
volatile
are optional in declarations and do not actually affect the type of declared
object.
Qualifier const
The
const
qualifier is used to indicate that variable value cannot be changed. Its value is set at initialization.
The mikroC PRO for PIC32 treats objects declared with the
const
qualifier the same as literals or preprocessor
constants. If the user tries to change an object declared with the
const
qualifier compiler will report an error.
For example:
const double PI = 3.14159;
Qualifier volatile
The
volatile
qualifier indicates that variable values can be changed both with or without user’s interference in the
program. The compiler should not optimize such variable.
Typedef Specifier
The
typedef
declaration introduces a name that, within its scope, becomes a synonym for the specified type. You can
use typedef declarations to construct shorter or more meaningful names for types already defined by the language or
declared by the user.
Typedef names allow you to encapsulate implementation details that may change. Unlike the
struct
,
union
, and
enum
declarations, the
typedef
declarations do not introduce new types, but new names for existing types.
The specifier
typedef
stands first in the declaration:
typedef <type_definition> synonym;
The
typedef
keyword assigns
synonym
to
<type_definition>
. The
synonym
needs to be a valid identifier.
A declaration starting with the
typedef
specifier does not introduce an object or a function of a given type, but rather
a new name for a given type. In other words, the
typedef
declaration is identical to a “normal” declaration, but instead
of objects, it declares types. It is a common practice to name custom type identifiers with starting capital letter — this is
not required by the mikroC PRO for PIC32.