[LISPWORKS][Common Lisp HyperSpec (TM)] [Previous][Up][Next]

Function CHAR-UPCASE, CHAR-DOWNCASE

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円) => #9円
 (char-downcase #9円) => #9円
 (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

Affected By: None.

Exceptional Situations:

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

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.

The following X3J13 cleanup issue, not part of the specification, applies to this section:

CHARACTER-PROPOSAL:2-1-1