char-code

char-code Function

Syntax:

char-code character → code

Arguments and Values:

character—a character .

code—a character code.

Description:

char-code returns the code attribute of character.

Examples:

;; An implementation using ASCII character encoding 
;; might return these values: 
(char-code #\$) → 36 
(char-code #\a) → 97 

Exceptional Situations:

Should signal an error of type type-error if character is not a character .

See Also:

char-code-limit

Expanded Reference: char-code

Getting the character code of common characters

char-code returns the implementation-dependent numeric code for a character. Most implementations use ASCII/Unicode code points.

;; On ASCII-based implementations:
(char-code #\A)
=> 65
(char-code #\a)
=> 97
(char-code #\0)
=> 48
(char-code #\Space)
=> 32

Character codes are bounded by char-code-limit

The returned code is always a non-negative integer less than char-code-limit.

(< (char-code #\a) char-code-limit)
=> T
(< (char-code #\Z) char-code-limit)
=> T
(integerp (char-code #\x))
=> T
(>= (char-code #\x) 0)
=> T

Round-tripping with code-char

char-code and code-char are inverse operations for valid character codes.

(code-char (char-code #\A))
=> #\A
(code-char (char-code #\Space))
=> #\Space
(char= #\z (code-char (char-code #\z)))
=> T

Comparing characters by code

Character codes reflect the implementation's ordering. For standard characters, the ordering is consistent with char<.

(< (char-code #\A) (char-code #\B))
=> T
(< (char-code #\a) (char-code #\z))
=> T
(< (char-code #\0) (char-code #\9))
=> T

Mapping characters to their codes

You can use char-code with map to get numeric codes for a string of characters.

(map 'list #'char-code "Hello")
=> (72 101 108 108 111)