Version: 4.1
##### 2.4.4Characters

 (alpha-char-p x) → t x : (characterp x)

Determines whether x is an alphabetic character.

 Examples: > (alpha-char-p #\a) t > (alpha-char-p #\3) () > (alpha-char-p 5) Dracula program broke the contract (-> char? any) on here; expected , given: 5

 (char str n) → t str : (stringp str) n : (and (integerp n) (>= n 0) (< n (length str)))

Extracts the character at the nth (0-based) position in the string str.

 Examples: > (char "hello" 0) #\h > (char "hello" 4) #\o > (char "hello" 100) () > (char 'symbol 3) length: expects argument of type ; given symbol

 (char< x y) → t x : (characterp x) y : (characterp y)

Determines whether the character code of x is less than that of y.

 Examples: > (char< #\a #\b) t > (char< #\b #\a) () > (char< #\b #\b) () > (char< #\A #\a) t > (char< 5 10) Dracula program broke the contract (-> char? char? any) on here; expected , given: 5

 (char<= x y) → t x : (characterp x) y : (characterp y)

Determines whether the character code of x is less than or equal to that of y.

 Examples: > (char<= #\a #\b) t > (char<= #\b #\a) () > (char<= #\b #\b) t > (char<= #\A #\a) t > (char<= 5 10) Dracula program broke the contract (-> char? char? any) on here; expected , given: 5

 (char> x y) → t x : (characterp x) y : (characterp y)

Determines whether the character code of x is greater than that of y.

 Examples: > (char> #\a #\b) () > (char> #\b #\a) t > (char> #\b #\b) () > (char> #\A #\a) () > (char> 5 10) Dracula program broke the contract (-> char? char? any) on here; expected , given: 5

 (char>= x y) → t x : (characterp x) y : (characterp y)

Determines whether the character code of x is greater than or equal to that of y.

 Examples: > (char>= #\a #\b) () > (char>= #\b #\a) t > (char>= #\b #\b) t > (char>= #\A #\a) () > (char>= 5 10) Dracula program broke the contract (-> char? char? any) on here; expected , given: 5

 (char-code char) → t char : (characterp char)

Returns the numeric code for the given character.

 Examples: > (char-code #\a) 97 > (char-code #\Z) 90 > (char-code 'symbol) Dracula program broke the contract (-> char? any) on here; expected , given: symbol

 (char-downcase char) → t char : (and (characterp char) (standard-char-p str))

Converts the given character to lowercase

 Examples: > (char-downcase #\A) #\a > (char-downcase #\a) #\a > (char-downcase 'symbol) char-downcase: expects argument of type ; given symbol

 (char-equal x y) → t x : (and (characterp x) (standard-char-p x)) y : (and (characterp y) (standard-char-p y))

Checks if the given characters are equal, ignoring to case.

 Examples: > (char-equal #\a #\a) t > (char-equal #\A #\a) t > (char-equal 'a #\a) Dracula program broke the contract (-> char? char? any) on here; expected , given: a

 (char-upcase char) → t char : (and (characterp char) (standard-char-p str))

Converts the given character to uppercase

 Examples: > (char-upcase #\A) #\A > (char-upcase #\a) #\A > (char-upcase 'symbol) char-upcase: expects argument of type ; given symbol

 (characterp x)

 Examples: > (characterp #\a) t > (characterp "a") ()

 (code-char x) → t x : (and (integerp x) (>= x 0) (< x 256))

Converts the given number into its character equivalent.

 Examples: > (code-char 0) #\nul > (code-char 97) #\a > (code-char 255) #\ÿ > (code-char 1000) #\Ϩ > (code-char #\5) Dracula program broke the contract (-> integer? any) on here; expected , given: #\5

 (digit-char-p x) → t x : (characterp x)

Determines whether the given character represents a numerical digit.

 Examples: > (digit-char-p #\3) 3 > (digit-char-p #\a) () > (digit-char-p 'symbol) Dracula program broke the contract (case-> (-> char? any) (-> char? (integer-in 2 36) any)) on here; expected , given: symbol

 (digit-to-char n) → t n : (and (integerp n) (<= 0 n) (>= 15 n))

Converts the given number into its equivalent character in hex notation.

 Examples: > (digit-to-char 7) #\7 > (digit-to-char 10) #\A > (digit-to-char 15) #\F > (digit-to-char #\7) number->string: expects type as 1st argument, given: #\7; other arguments were: 16

 (lower-case-p [x (and (characterp x) (standard-char-p x))])

#<procedure:t>Determines if x is a lowercase alphabetic character.

 Examples: > (lower-case-p #\a) t > (lower-case-p #\A) () > (lower-case-p 5) Dracula program broke the contract (-> char? any) on here; expected , given: 5

 (standard-char-p x) → t x : (characterp x)

Checks if the given character is a member of the *standard-chars*. This includes the standard punctuation and alphanumeric characters, along with #\newline and #\space.

 Examples: > (standard-char-p #\a) reference to undefined identifier: standard-char-p > (standard-char-p #\5) reference to undefined identifier: standard-char-p > (standard-char-p 5) reference to undefined identifier: standard-char-p

 (upper-case-p x) → t x : (and (characterp x) (standard-char-p x))

Determines if x is an upper-case alphabetic character.

 Examples: > (upper-case-p #\A) t > (upper-case-p #\a) () > (upper-case-p 5) Dracula program broke the contract (-> char? any) on here; expected , given: 5