|
ANSI Common Lisp 13 Characters 13.2 Dictionary of Characters
13.2.14 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 Documentation 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.
- Allegro CL Implementation Details:
-
None.
|