char-upcase, char-downcase

char-upcase, char-downcase Function

Syntax:

char-upcase character → corresponding-character

char-downcase character → corresponding-character

Arguments and Values:

character, corresponding-character—a character .

Description:

If character is a lowercase character , char-upcase returns the corresponding uppercase character . Otherwise, char-upcase just returns the given character.

If character is an uppercase character , char-downcase returns the corresponding lowercase character . Otherwise, char-downcase just returns the given character.

The result only ever differs from character in its code attribute; all implementation-defined attributes are preserved.

Examples:

(char-upcase #\a) → #\A 
(char-upcase #\A) → #\A 
(char-downcase #\a) → #\a 
(char-downcase #\A) → #\a 
(char-upcase #\9) → #\9 
(char-downcase #\9) → #\9 
(char-upcase #\@) → #\@ 
(char-downcase #\@) → #\@ 
;; Note that this next example might run for a very long time in 
;; some implementations if CHAR-CODE-LIMIT happens to be very large 
;; for that implementation. 
(dotimes (code char-code-limit) 
  (let ((char (code-char code))) 
    (when char 
      (unless (cond ((upper-case-p char) (char= (char-upcase (char-downcase char)) char)) ((lower-case-p char) (char= (char-downcase (char-upcase char)) char)) 
		    (t (and (char= (char-upcase (char-downcase char)) char) 
			    (char= (char-downcase (char-upcase char)) char)))) 
	(return char))))) 
→ NIL 

Exceptional Situations:

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

See Also:

upper-case-p, alpha-char-p, Section 13.1.4.3 (Characters With Case), Section 13.1.10 (Documen tation of Implementation-Defined Scripts)

Notes:

If the corresponding-char is different than character, then both the character and the corresponding char have case.

Since char-equal ignores the case of the characters it compares, the corresponding-character is always the same as character under char-equal.

Expanded Reference: char-upcase, char-downcase

tip

TODO: Please contribute to this page by adding explanations and examples

(char-upcase, char-downcase )