Ada Reference Manual (Ada 2022)

3.5.2 Character Types

Static Semantics

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 points of Row 00 (also known as Latin-1) of the ISO/IEC 10646:2020 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 characters of Row 00 has a corresponding language-defined name, which is not usable as an enumeration literal, but which is usable with the attributes Image, Wide_Image, Wide_Wide_Image, Value, Wide_Value, and Wide_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 points of the ISO/IEC 10646:2020 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. Each of the graphic_characters has a corresponding character_literal.

The predefined type Wide_Wide_Character is a character type whose values correspond to the 2147483648 code points of the ISO/IEC 10646:2020 character set. Each of the graphic_characters has a corresponding character_literal in Wide_Wide_Character. The first 65536 values of Wide_Wide_Character have the same character_literal or language-defined name as defined for Wide_Character.

The characters whose code point is larger than 16#FF# and which are not graphic_characters have language-defined names which are formed by appending to the string "Hex_" the representation of their code point in hexadecimal as eight extended digits. As with other language-defined names, these names are usable only with the attributes (Wide_)Wide_Image and (Wide_)Wide_Value; they are not usable as enumeration literals.

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NOTE 1 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.

NOTE 2 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 13.4.

Examples

Example of a character type:

type Roman_Digit is ('I', 'V', 'X', 'L', 'C', 'D', 'M');