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  • char-upcase charactercorresponding-character
  • char-downcase charactercorresponding-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)


(char-upcase #\A)


(char-downcase #\a)


(char-downcase #\A)


(char-upcase #\9)


(char-downcase #\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 ;; TODO fix, does not return NIL on SBCL, ECL or CMUCL

Affected By


Exceptional Situations

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

See Also

Function UPPER-CASE-P, Function ALPHA-CHAR-P, {\secref\CharactersWithCase}, {\secref\ImplementationDefinedScripts}


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.