— 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 Sequence Functions.

— 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. The function converts a unibyte string to multibyte if necessary to insert a character.

— 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.