www.delorie.com/gnu/docs/elisp-manual-21/elisp_36.html   search  
Buy the book!

GNU Emacs Lisp Reference Manual

[ < ] [ > ]   [ << ] [ Up ] [ >> ]         [Top] [Contents] [Index] [ ? ]

2.3.11 Bool-Vector Type

A bool-vector is a one-dimensional array of elements that must be t or nil.

The printed representation of a bool-vector is like a string, except that it begins with `#&' followed by the length. The string constant that follows actually specifies the contents of the bool-vector as a bitmap--each "character" in the string contains 8 bits, which specify the next 8 elements of the bool-vector (1 stands for t, and 0 for nil). The least significant bits of the character correspond to the lowest indices in the bool-vector. If the length is not a multiple of 8, the printed representation shows extra elements, but these extras really make no difference.

(make-bool-vector 3 t)
     => #&3"\007"
(make-bool-vector 3 nil)
     => #&3"\0"
;; These are equal since only the first 3 bits are used.
(equal #&3"\377" #&3"\007")
     => t

  webmaster   donations   bookstore     delorie software   privacy  
  Copyright 2003   by The Free Software Foundation     Updated Jun 2003