Functions that Operate on Arrays

In this section, we describe the functions that accept all types of arrays.

Function: arrayp object

This function returns t if object is an array (i.e., a vector, a string, a bool-vector or a char-table).

(arrayp [a])
     => t
(arrayp "asdf")
     => t
(arrayp (syntax-table))    ;; A char-table.
     => t

Function: aref array index

This function returns the indexth element of array. The first element is at index zero.

(setq primes [2 3 5 7 11 13])
     => [2 3 5 7 11 13]
(aref primes 4)
     => 11
(aref "abcdefg" 1)
     => 98           ; `b' is ASCII code 98.

See also the function elt, in section Sequences.

Function: aset array index object

This function sets the indexth element of array to be object. It returns object.

(setq w [foo bar baz])
     => [foo bar baz]
(aset w 0 'fu)
     => fu
w
     => [fu bar baz]

(setq x "asdfasfd")
     => "asdfasfd"
(aset x 3 ?Z)
     => 90
x
     => "asdZasfd"

If array is a string and object is not a character, a wrong-type-argument error results. If array is a string and object is character, but object does not use the same number of bytes as the character currently stored in (aref object index), that is also an error. See section Splitting Characters.

Function: fillarray array object

This function fills the array array with object, so that each element of array is object. It returns array.

(setq a [a b c d e f g])
     => [a b c d e f g]
(fillarray a 0)
     => [0 0 0 0 0 0 0]
a
     => [0 0 0 0 0 0 0]
(setq s "When in the course")
     => "When in the course"
(fillarray s ?-)
     => "------------------"

If array is a string and object is not a character, a wrong-type-argument error results.

The general sequence functions copy-sequence and length are often useful for objects known to be arrays. See section Sequences.

Go to the first, previous, next, last section, table of contents.