ABL electronic PIC12 Benutzerhandbuch
Enumeration Constants
Enumeration constants are identifiers defined in enum type declarations. The iden-
tifiers are usually chosen as mnemonics to assist legibility. Enumeration constants
are of
tifiers are usually chosen as mnemonics to assist legibility. Enumeration constants
are of
int
type. They can be used in any expression where integer constants are
valid.
For example:
enum
weekdays {SUN = 0, MON, TUE, WED, THU, FRI, SAT};
The identifiers (enumerators) used must be unique within the scope of the enum
declaration. Negative initializers are allowed. See Enumerations for details of
declaration. Negative initializers are allowed. See Enumerations for details of
enum
declarations.
Pointer Constants
A pointer or the pointed-at object can be declared with the
const
modifier.
Anything declared as a const cannot be have its value changed. It is also illegal
to create a pointer that might violate the nonassignability of a constant object.
to create a pointer that might violate the nonassignability of a constant object.
Constant Expressions
A constant expression is an expression that always evaluates to a constant and
consists only of constants (literals) or symbolic constants. It is evaluated at com-
pile-time and it must evaluate to a constant that is in the range of representable
values for its type. Constant expressions are evaluated just as regular expressions
are.
consists only of constants (literals) or symbolic constants. It is evaluated at com-
pile-time and it must evaluate to a constant that is in the range of representable
values for its type. Constant expressions are evaluated just as regular expressions
are.
Constant expressions can consist only of the following: literals, enumeration con-
stants, simple constants (no constant arrays or structures), sizeof operators.
stants, simple constants (no constant arrays or structures), sizeof operators.
Constant expressions cannot contain any of the following operators, unless the
operators are contained within the operand of a
operators are contained within the operand of a
sizeof
operator: assignment,
comma, decrement, function call, increment.
You can use a constant expression anywhere that a constant is legal.
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