ELisp: Character Type

What is Char Type

In emacs lisp, character is represented as integer of the character's Codepoint .

For example, the char “a” in elisp is just 97, because its codepoint is 97.

Note: elisp “Character Type” is not technically a “type” of value in the sense of most programing languages, because there is no way to distinguish integer from char. There is no function that returns true/false on whether a value is a character type. Whether a integer is a character depends on programer's intention.

Char Syntax

Char can also be represented like this ?a for easy reading. ?a means the character “a”.

You can also represent char by (string-to-char "a")

(equal 97 ?a ) ;; t
(equal 97 (string-to-char "a")) ;; t

Find a Char's Codepoint

• Emacs: describe-char, Char Name, Cursor Position

Useful Functions on Character

char-before

(char-before) return the unicode codepoint (integer) of character before cursor.

char-after

(char-after) return the unicode codepoint (integer) of character after cursor.

char-to-string

(char-to-string CHAR) convert a CHAR (unicode codepoint (integer)) to string of single character.

string-to-char

(string-to-char STRING) return the first char in string. (return a integer that's the char's unicode codepoint)

char-equal

(char-equal C1 C2).

Return t if two characters match, but dependent on a Buffer Local Variable case-fold-search.

Case is ignored if case-fold-search is non-nil in the current buffer.

🛑 WARNING: when at beginning of buffer, char-before return nil. Using char-equal result error because argument needs to be integer. So, in general, better use eq. [see ELisp: Equality Test]

;; check if char before is a newline
(char-equal (char-before ) 10)

ASCII Control Chars and Backslash

Syntax of the form ?\char may have special meaning, depending what char is. They either represent a ASCII control character, or just the character char. For example, ?\n is the newline char. ?\\ is backslash char.

Here's a list of special meaning with the backslash:

[see ASCII Characters]

Reference

• Character Type (ELISP Manual)
• Basic Char Syntax (ELISP Manual)