Ada Reference Manual (Ada 2022) — Legal Information

# 2.4.2 Based Literals

1
A based_literal is a numeric_literal expressed in a form that specifies the base explicitly.

#### Syntax

2
based_literal ::=
base # based_numeral [.based_numeral] # [exponent]
3
base ::= numeral
4
based_numeral ::=
extended_digit {[underline] extended_digit}
5
extended_digit ::= digit | A | B | C | D | E | F

#### Legality Rules

6
The base (the numeric value of the decimal numeral preceding the first #) shall be at least two and at most sixteen. The extended_digits A through F represent the digits ten through fifteen, respectively. The value of each extended_digit of a based_literal shall be less than the base.

#### Static Semantics

7
The conventional meaning of based notation is assumed. An exponent indicates the power of the base by which the value of the based_literal without the exponent is to be multiplied to obtain the value of the based_literal with the exponent. The base and the exponent, if any, are in decimal notation.
8
The extended_digits A through F can be written either in lower case or in upper case, with the same meaning.

#### Examples

9
Examples of based literals:
10
2#1111_1111# 16#FF# 016#0ff# -- integer literals of value 255
16#E#E1 2#1110_0000# -- integer literals of value 224
16#F.FF#E+2 2#1.1111_1111_1110#E11 -- real literals of value 4095.0

Ada 2005 and 2012 Editions sponsored in part by Ada-Europe