CLCS
Accessor

bit, sbit

bit bit-array &rest subscripts ⇒ bit

sbit bit-array &rest subscripts ⇒ bit

(setf (bit bit-array &rest subscripts) new-bit)
(setf (sbit bit-array &rest subscripts) new-bit)

Arguments and Values

bit-arrayfor bit, a bit array; for sbit, a simple bit array.
subscriptsa list of valid array indices for the bit-array.
bita bit.

Description

bit and sbit access the bit-array element specified by subscripts.

These functions ignore the fill pointer when accessing elements.

Examples

 (bit (setq ba (make-array 8 
                            :element-type 'bit 
                            :initial-element 1))
       3) ⇒  1
 (setf (bit ba 3) 0) ⇒  0
 (bit ba 3) ⇒  0
 (sbit ba 5) ⇒  1
 (setf (sbit ba 5) 1) ⇒  1
 (sbit ba 5) ⇒  1

Notes

bit and sbit are like aref except that they require arrays to be a bit array and a simple bit array, respectively.

bit and sbit, unlike char and schar, allow the first argument to be an array of any rank.