Number Constants

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Number constants

as distinguishes three kinds of numbers according to how they are stored in the target machine.

- Integers are numbers that would fit into an int in the C language.
- Bignums are integers, but they are stored in more than 32 bits.
- Flonums are floating point numbers, described in .

Integers

A binary integer is 0b or 0B followed by one or more of the binary digits, 01.

An octal integer is 0 followed by zero or more of the octal digits (0, 1, 2, 3, 4, 5, 6, 7).

A decimal integer starts with a non-zero digit followed by zero or more digits (0, 1, 2, 3, 4, 5, 6, 7, 8, 9).

`0b` | invalid
`0bO` | valid

A hexadecimal integer is 0x, or 0X, followed by zero or more hexadecimal digits (`A`, B, `C`, D, E, F, a, b, c, d, e, f and 0, 1, 2, 3, 4, 5, 6, 7, 8, 9). Integers have the usual values. To denote a negative integer, use the prefix operator (-), discussed under expressions (see Prefix operator).

`0x` | valid = 0+0
`0x1` | valid

Bignums

A bignum has the same syntax and semantics as an integer except that the number (or its negative) takes more than 32 bits to represent in binary. The distinction is made because in some places integers are permitted while bignums are not.

Flonums

A flonum represents a floating point number. The translation is indirect: a decimal floating point number from the text is converted by as to a generic binary floating point number of more than sufficient precision. This generic floating point number is converted to a particular computer’s floating point format (or formats) by a portion of as specialized to that computer.

A flonum is written by using (in order) the following:

- The digit 0. (0 is optional on the HPPA.)
- A letter, to tell as the rest of the number is a flonum. e is recommended. Case is not important.

- On the H8/300, H8/500, Hitachi SH, and AMD 29K architectures, the letter must be one of the letters: D, F, P, R, S, or X (in upper or lower case).
- On the Intel 960 architecture, the letter must be one of the letters: D, F, or T (in upper or lower case).
- On the HPPA architecture, the letter must be E (upper case only).

- An optional sign: either + or -.
- An optional integer part: zero or more decimal digits.
- An optional fractional part: (.) followed by zero or more decimal digits.
- An optional exponent, consisting of:

- An E or e.
- Optional sign: either + or -.
- One or more decimal digits.

At least one of the integer part or the fractional part must be present. The floating point number has the usual base-10 value.

as does all processing using integers. Flonums are computed independently of any floating point hardware in the computer running as.

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