Elisp: String Functions

By Xah Lee. Date: . Last updated: .

Here is a complete list of string functions.

Basic String Functions

length
(length SEQUENCE)

Return the length of a Sequence.

(length "abc")
;; 3
substring
(substring STRING &optional FROM TO)

return a substring from position FROM to TO. Position start at 0. By default, TO is to end of string, and FROM is 0. If negative, count from right.

(substring "abc123" 0 3)
;; "abc"
concat
(concat &rest SEQUENCES)

join all the arguments and make the result a string.

(concat "some" "thing")
split-string
(split-string STRING &optional SEPARATORS OMIT-NULLS TRIM)

Split STRING into substrings bounded by matches for SEPARATORS.

;; split string into parts, returns a list
(split-string "xy_007_cat" "_")

String To/From Number

Buffer Text to String

String to Buffer

Match String by Regex

string-match

Get Regex Captured String

match-string

Regex Replace in String

replace-regexp-in-string

Trim String

These are new in Emacs 24.4 (Released 2014-10) . Before Emacs 28 (Released 2022-04) , you need to first load (require 'subr-x) . [see Emacs Version History]

Other String Functions

To use the following, you need to first load a lib:

(require 'subr-x)

Strings and Characters (ELISP Manual)

String Functions Reference

Here's a complete list of string functions for reference.

Predicates for Strings (ELISP Manual)

Creating Strings (ELISP Manual)

Modifying Strings (ELISP Manual)

Text Comparison (ELISP Manual)

Text Comparison (ELISP Manual)

Case Conversion (ELISP Manual)

Case Tables (ELISP Manual)

Emacs Lisp String