Mikroelektronika MIKROE-724 データシート
216
mikoBasic PRO for dsPIC30/33 and PIC24
MikroElektronika
Typedef Specifier
The specifier
typedef
introduces a synonym for a specified type. The
typedef
declarations are used to construct
shorter or more convenient names for types already defined by the language or declared by the user.
The specifier
typedef
stands first in the declaration:
typedef synonym as <type_definition>
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 mikroBasic PRO for dsPIC.
For example:
‘ Let’s declare a synonym for “word”
typedef Distance as word
‘ Now, synonym “Distance” can be used as type identifier:
dim i as Distance ‘ declare variable i of word
In the
typedef
declaration, as in any other declaration, several types can be declared at once. For example:
typedef ^Pti, Array[10] as byte
Here,
Pti
is a synonym for type “pointer to
int
”, and
Array
is a synonym for type “array of 10
byte
elements”.
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 qualifier
const
implies that a declared object will not change its value during runtime. In declarations with the
const
qualifier all objects need to be initialized.
The mikroBasic PRO for dsPIC30/33 and PIC24 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 PI as byte = 3.14159