CLHS: Function DIGIT-CHAR-P

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Function DIGIT-CHAR-P

Syntax:

digit-char-p char `&optional` radix => weight

Arguments and Values:

char---a character.

radix---a radix. The default is `10`.

weight---either a non-negative integer less than radix, or false.

Description:

Tests whether char is a digit in the specified radix (i.e., with a weight less than radix). If it is a digit in that radix, its weight is returned as an integer; otherwise nil is returned.

Examples:

     (digit-char-p #\5)    =>  5
     (digit-char-p #\5 2)  =>  false
     (digit-char-p #\A)    =>  false
     (digit-char-p #\a)    =>  false
     (digit-char-p #\A 11) =>  10
     (digit-char-p #\a 11) =>  10
     (mapcar #'(lambda (radix)
                 (map 'list #'(lambda (x) (digit-char-p x radix))
                      "059AaFGZ"))
             '(2 8 10 16 36))
     =>  ((0 NIL NIL NIL NIL NIL NIL NIL)
         (0 5 NIL NIL NIL NIL NIL NIL)
         (0 5 9 NIL NIL NIL NIL NIL)
         (0 5 9 10 10 15 NIL NIL)
         (0 5 9 10 10 15 16 35))

Affected By:

None. (In particular, the results of this predicate are independent of any special syntax which might have been enabled in the current readtable.)

Exceptional Situations: None.

See Also:

alphanumericp

Notes:

Digits are graphic characters.

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