Emacs Lisp: Character Type
In emacs lisp, character is represented as integer of the character's Unicode 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's no way to distinguish integer from char. There is no function that returns true/false on whether a value is a character type. (by comparison, there are
symbolp, etc.) Whether a integer is a character depends on programer's intention.
Char can also be represented like this
?a for easy reading.
?a means the character a.
You can also represent char by
(equal 97 ?a ) ;; t (equal 97 (string-to-char "a")) ;; t
Find a Char's Codepoint
Useful Function on Character
(char-before)return the unicode codepoint (integer) of character before cursor.
(char-after)return the unicode codepoint (integer) of character after cursor.
(char-to-string CHAR)convert a CHAR (unicode codepoint (integer)) to string of single character.
(string-to-char STRING)return the first char in string. (return a integer that's the char's unicode codepoint)
(char-equal C1 C2). Return t if two characters match, optionally ignoring case. Case is ignored if case-fold-search is non-nil in the current buffer.
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.
?\n is the newline char.
?\\ is backslash char.
Here's a list of special meaning with the backslash:
- 7 ; control-g, C-g
- 8 ; backspace, BS, C-h
- 9 ; tab, TAB, C-i
- 10 ; newline, C-j
- 11 ; vertical tab, C-k
- 12 ; formfeed character, C-l
- 13 ; carriage return, RET, C-m
- 27 ; escape character, ESC, C-[
- 32 ; space character, SPC
- 92 ; backslash character, \
- 127 ; delete character, DEL
[see ASCII Characters]
(info "(elisp) Character Type")
(info "(elisp) Basic Char Syntax")