- An enumeration type is said to be a character type if at least one of its
enumeration literals is a character_literal.
- The predefined type Character is a character type whose values correspond
to the 256 code positions of Row 00 (also known as Latin-1) of the ISO 10646
Basic Multilingual Plane (BMP). Each of the graphic characters of Row 00 of
the BMP has a corresponding character_literal in Character. Each of the nongraphic
positions of Row 00 (0000-001F and 007F-009F) has a corresponding language-defined
name, which is not usable as an enumeration literal, but which is usable with
the attributes (Wide_)Image and (Wide_)Value; these names are given in the
definition of type Character in A.1, ``The Package
Standard'', but are set in italics.
- The predefined type Wide_Character is a character type whose values
correspond to the 65536 code positions of the ISO 10646 Basic Multilingual
Plane (BMP). Each of the graphic characters of the BMP has a corresponding
character_literal in Wide_Character. The first 256 values of Wide_Character
have the same character_literal or language-defined name as defined for
Character. The last 2 values of Wide_Character correspond to the nongraphic
positions FFFE and FFFF of the BMP, and are assigned the language-defined
names FFFE and FFFF. As with the other language-defined names for nongraphic
characters, the names FFFE and FFFF are usable only with the attributes
(Wide_)Image and (Wide_)Value; they are not usable as enumeration literals.
All other values of Wide_Character are considered graphic characters, and
have a corresponding character_literal.
- In a nonstandard mode, an implementation may provide other
interpretations for the predefined types Character and Wide_Character, to
conform to local conventions.
- If an implementation supports a mode with alternative interpretations for
Character and Wide_Character, the set of graphic characters of Character should
nevertheless remain a proper subset of the set of graphic characters of Wide_Character.
Any character set ``localizations'' should be reflected in the results of
the subprograms defined in the language-defined package Characters.Handling
(see A.3) available in such a mode. In a mode with
an alternative interpretation of Character, the implementation should also
support a corresponding change in what is a legal identifier_letter.
(23) The language-defined library package Characters.Latin_1 (see
A.3.3) includes the declaration of constants denoting control characters,
lower case characters, and special characters of the predefined type Character.
(24) A conventional character set such as EBCDIC can be declared as a character
type; the internal codes of the characters can be specified by an enumeration_representation_clause
as explained in clause 13.4.
- Example of a character type:
type Roman_Digit is ('I', 'V', 'X', 'L', 'C', 'D', 'M');
-- Email comments, additions, corrections, gripes, kudos, etc. to:
Magnus Kempe -- Magnus.Kempe@di.epfl.ch
Page last generated: 95-03-12