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Miscellaneous Character Operations

procedure: char? object

Returns #t if object is a character; otherwise returns #f.

procedure: char-upcase char

procedure: char-downcase char

Returns the uppercase or lowercase equivalent of char if char is a letter; otherwise returns char. These procedures return a character char2 such that (char-ci=? char char2).

procedure+: char->digit char [radix]

If char is a character representing a digit in the given radix, returns the corresponding integer value. If you specify radix (which must be an exact integer between 2 and 36 inclusive), the conversion is done in that base, otherwise it is done in base 10. If char doesn't represent a digit in base radix, char->digit returns #f.

Note that this procedure is insensitive to the alphabetic case of char.

(char->digit #\8)                       =>  8
(char->digit #\e 16)                    =>  14
(char->digit #\e)                       =>  #f

procedure+: digit->char digit [radix]

Returns a character that represents digit in the radix given by radix. Radix must be an exact integer between 2 and 36 (inclusive), and defaults to 10. Digit, which must be an exact non-negative integer, should be less than radix; if digit is greater than or equal to radix, digit->char returns #f.

(digit->char 8)                         =>  #\8
(digit->char 14 16)                     =>  #\E

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