char-upcase, char-downcaseFunction

    char-upcase character corresponding-character
    char-downcase character corresponding-character
    Arguments and Values

    character, corresponding-character — a character.


    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.

     (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))))) 
    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 (Characters With Case), Section 13.1.10 (Documentation of Implementation-Defined Scripts)


    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.