CLHS: Variable *PRINT-BASE*, *PRINT-RADIX*

#

Variable *PRINT-BASE*, *PRINT-RADIX*

Value Type:

*print-base*---a radix. *print-radix*---a generalized boolean.

Initial Value:

The initial value of *print-base* is `10`. The initial value of *print-radix* is false.

Description:

*print-base* and *print-radix* control the printing of rationals. The value of *print-base* is called the current output base.

The value of *print-base* is the radix in which the printer will print rationals. For radices above `10`, letters of the alphabet are used to represent digits above `9`.

If the value of *print-radix* is true, the printer will print a radix specifier to indicate the radix in which it is printing a rational number. The radix specifier is always printed using lowercase letters. If *print-base* is `2`, `8`, or `16`, then the radix specifier used is `#b`, `#o`, or `#x`, respectively. For integers, base ten is indicated by a trailing decimal point instead of a leading radix specifier; for ratios, `#10r` is used.

Examples:

     (let ((*print-base* 24.) (*print-radix* t))
       (print 23.))
    >>  #24rN
    =>  23
     (setq *print-base* 10) =>  10
     (setq *print-radix* nil) =>  NIL
     (dotimes (i 35)
        (let ((*print-base* (+ i 2)))           ;print the decimal number 40
          (write 40)                            ;in each base from 2 to 36
          (if (zerop (mod i 10)) (terpri) (format t " "))))
    >>  101000
    >>  1111 220 130 104 55 50 44 40 37 34
    >>  31 2C 2A 28 26 24 22 20 1J 1I
    >>  1H 1G 1F 1E 1D 1C 1B 1A 19 18
    >>  17 16 15 14
    =>  NIL
     (dolist (pb '(2 3 8 10 16))
        (let ((*print-radix* t)                 ;print the integer 10 and
              (*print-base* pb))                ;the ratio 1/10 in bases 2,
         (format t "~&~S  ~S~%" 10 1/10)))        ;3, 8, 10, 16
    >>  #b1010  #b1/1010
    >>  #3r101  #3r1/101
    >>  #o12  #o1/12
    >>  10.  #10r1/10
    >>  #xA  #x1/A
    =>  NIL

Affected By:

Might be bound by format, and write, write-to-string.

See Also:

format, write, write-to-string

Notes: None.

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