digit-char
weight &optional radix => char
weight—a non-negative integer.
radix—a radix. The default is 10.
char—a character or false.
If weight is less than radix, digit-char returns a character which has that weight when considered as a digit in the specified radix. If the resulting character is to be an alphabetic_1 character, it will be an uppercase character.
If weight is greater than or equal to radix, digit-char returns false.
(digit-char 0) => #\0 (digit-char 10 11) => #\A (digit-char 10 10) => false (digit-char 7) => #\7 (digit-char 12) => false (digit-char 12 16) => #\C ;not #\c (digit-char 6 2) => false (digit-char 1 2) => #\1
digit-char-p , graphic-char-p , Character Syntax