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Index
*read-base* Reader Dictionary *read-eval*
Variable

*read-default-float-format*

Value Type

one of the atomic type specifiers short-float, single-float, double-float, or long-float, or else some other type specifier defined by the implementation to be acceptable.

Initial Value

The symbol single-float.

Description

Controls the floating-point format that is to be used when reading a floating-point number that has no exponent marker or that has e or E for an exponent marker. Other exponent markers explicitly prescribe the floating-point format to be used.

The printer uses *read-default-float-format* to guide the choice of exponent markers when printing floating-point numbers.

Examples

 (let ((*read-default-float-format* 'double-float))
   (read-from-string "(1.0 1.0e0 1.0s0 1.0f0 1.0d0 1.0L0)"))
⇒  (1.0   1.0   1.0   1.0 1.0   1.0)   ;Implementation has float format F.
⇒  (1.0   1.0   1.0s0 1.0 1.0   1.0)   ;Implementation has float formats S and F.
⇒  (1.0d0 1.0d0 1.0   1.0 1.0d0 1.0d0) ;Implementation has float formats F and D.
⇒  (1.0d0 1.0d0 1.0s0 1.0 1.0d0 1.0d0) ;Implementation has float formats S, F, D.
⇒  (1.0d0 1.0d0 1.0   1.0 1.0d0 1.0L0) ;Implementation has float formats F, D, L.
⇒  (1.0d0 1.0d0 1.0s0 1.0 1.0d0 1.0L0) ;Implementation has formats S, F, D, L.

Backlinks

Multiple Possible Textual Representations, Printing Floats, read, read-preserving-whitespace, Reader Dictionary, Symbols in the COMMON-LISP Package, Syntax of a Float, Tilde E: Exponential Floating-Point, Variables that affect the Lisp Reader, with-standard-io-syntax, write, prin1, print, pprint, princ, write-to-string, prin1-to-string, princ-to-string