HP 3000 Manuals HP 3000 Manuals
Enumeration
The identifiers in an enumeration list are declared as constants.
Syntax
enum-specifier ::=
enum[ identifier] {enumerator-list}
enum [ identifier ]
enumerator-list ::=
enumerator
enumerator-list , enumerator
enumerator ::=
enumeration-constant
enumeration-constant = constant-expression
enumeration-constant ::= identifier
Description
The identifiers defined in the enumerator list are enumeration constants
of type int. As constants, they can appear wherever integer constants
are expected. A specific integer value is associated with an enumeration
constant by following the constant with an equal sign ( = ) and a
constant expression. If you define the constants without using the equal
sign, the first constant will have the value of zero and the second will
have the value of one, and so on. If an enumerator is defined with the
equal sign followed by a constant expression, that identifier will take
on the value specified by the expression. Subsequent identifiers
appearing without the equal sign will have values that increase by one
for each constant. For example,
enum color {red, blue, green=5, violet};
defines red as 0, blue as 1, green as 5, and violet as 6.
Enumeration constants share the same name space as ordinary identifiers.
They have the same scope as the scope of the enumeration in which they
are defined. Note that enum constant names must be unique.
The identifier in the enum declaration behaves like the tags used in
structure and union declarations. If the tag has already been declared,
you can use the tag as a reference to that enumerated type later in the
program.
enum color x, y[100];
In this example, the color enumeration tag declares two objects. The x
object is a scalar enum object, while y is an array of 100 enums.
An enumeration tag cannot be used before its enumerators are declared.
Examples
enum color {RED, GREEN, BLUE};
enum objectkind {triangle, square=5, circle}; /* circle == 6 */