Elisp: Join Strings, Codepoints to String

Join Strings

concat

(concat &rest str1 str2 etc)

join strings.

(concat "some" "thing")

Codepoints to String

use concat

Any arg can be a List or Vector, but each element must be a integer, each is the Codepoint of a char. 〔see Elisp: Character Type〕

;; if arg is vector or list, their elements must be integers, as codepoints for char
(concat (vector 97 98 99))
;; "abc"

(concat (list 32))
;; " "
;; 32 is space

(concat (vector 97 98 99 ) (list 32) "thing")
;; "abc thing"

;; this is an error of wrong-type-argument
;; (concat (vector "a" "b" )  "thing")

List of Strings to String, with Separators

mapconcat

(mapconcat function sequence separator)

Convert strings in a Sequence to a single string, with separator between them, also map a function to each.

;; list of numbers to string
(mapconcat 'number-to-string '(1 2 3) ",")
;; "1,2,3"

;; list to string
(mapconcat 'identity '("a" "b" "c") ",")
;; "a,b,c"

;; vector to string
(mapconcat 'number-to-string [1 2 3] ",")
;; "1,2,3"

Other Join String Functions

• format → join by embedding into arbitrary text. Elisp: Format String

• byte-to-string