#### 13.2.11 digit-char-p [Function]

`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.)

#### See Also::

alphanumericp

#### Notes::

Digits are graphic characters.