Page 158 - DCAP507_SYSTEM_SOFTWARE

System Software

Notes C:
Enumerated-type-identifier (i1, i2, i3,à.in);
enum
item-list

Identifier for
enumerated type
reserved word
for example,
enum time of day {am, pm};
enumerated data type item-list

once variables have been declared as enumerated data types, they can only have the values
defined in the item-list. For example,
enum time of day X, Y;

enum time of day X, Y;
data - type variables
declares the variables X and Y to be of type time of day and can assume values from the item-list.

Subrange Data Type

When a data item takes a range of values which is a subrange of the values described by some
existing type i.e. primitive or enumerated, its type may be defined as a subrange of that host
type. The syntax is as follows:
type

type-identifier = lowerlimit..upperlimit
where lowerlimit and upperlimit must be constant, or previously defined constant identifier
(of type integer) or item of an enumerated-type-list. Moreover, lowerlimit is always less than
the upperlimit.

Example: of subrange type declaration are:
const
M = 15;
N = 2;
type
VALUE = 'N'.. 'M' ;

NUMBER = 1..100 ;
LETTER = 'A'.. 'Z' ;
Variables of these type may be declared as
Var
RESULT, answer : NUMBER;

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