Elisp Strings

Returns the length of string.

  (length SEQUENCE)

  ;; E.G.
  (length "abc") ; => 3

  (substring STRING &optional FROM TO)

  ;; e.g.
  (substring "abs123" 0 3) ; => "abs"

Return a substring from position FROM to TO. 0-indexed string. By default, TO is to the end of string, and FROM is 0.

If negative, count from right.

First, introduce concat function. It accepts a list of arguments that each argument can be a string, a list or a vector of characters.

  (concat &rest SEQUENCES)

Next, introduce mapconcat function. It applies FUNCTION to each argument of SEQUENCE, then concatenate results together separated by SEPARATOR.

  (mapconcat FUNCTION SEQUENCE &optional SEPARATOR)

Thirdly, vconcat function takes multiple vectors or lists and flattens them into a single vector. It can also convert a string into a vector of characters (integers)

  (vconcat &rest SEQUENCES)

  ;; e.g.
  (vconcat [a b c] [d e f])  ; => [a b c d e f]
  (vconcat '(1 2 3) [4 5 6]) ; => [1 2 3 4 5 6]
  (vconcat "hello")          ; => [104 101 108 108 111]

Similarly, there’s a function called append which does similar job, but makes the result a list. All arguments except the last argument are copied.

  (append &rest SEQUENCES)

  ;; e.g.

  (append '(1 2) '(3 4) '(5 6)) ; => (1 2 3 4 5 6)

  (split-string STRING &optional SEPARATOR OMIT-NULLS TRIM)

  ;; e.g.
  (split-string "x_y_z" "_") ; => ("x" "y" "z")

It splits a string with separator and returns a list.