Elisp: Convert Hexadecimal to Decimal

Here's how to convert hexadecimal/decimal in lisp code.

Decimal to Hexadecimal

use format

;; decimal to hexadecimal
(format "%x" 255)
;; "ff"

Hexadecimal to Decimal

use string-to-number

;; hexadecimal to decimal
(string-to-number "ff" 16)
;; 255