emacs - elisp下如何显示不同基数的数字？

Question

众所周知，elisp 支持不同基数的数字，例如#20r1j在 base-10 中等于 39。我想显示#20r1j为#20r1j. 但是(format "%d" #20r1j)给我39。如何将数字保持在其原始基数？

Answer 1

As a format string, you are quite limited in the bases you can display:

%d means print as number in decimal (%o octal, %x hex).
%X is like %x, but uses upper case.

You can use the calc library to manage this for you, however:

(require 'calc-bin)

(let ((calc-number-radix 20))
  (math-format-radix 39))
"1J"

(let ((calc-number-radix 20))
  (math-format-radix #20r1j))
"1J"

As with the read syntax you're using, allowed values of calc-number-radix run from 2 to 36.