elt sequence index → object

(setf (elt sequence index) new-object)

sequence — a proper sequence.

index — a valid sequence index for sequence.

object — an object.

new-object — an object.

Accesses the element of sequence specified by index.

(setq str (copy-seq "0123456789")) → "0123456789" 
(elt str 6) → #\6 
(setf (elt str 0) #\#) → #\# 
str → "#123456789"

Should be prepared to signal an error of type type-error if sequence is not a proper sequence. Should signal an error of type type-error if index is not a valid sequence index for sequence.

aref, nth, Section 3.2.1 (Compiler Terminology)

aref may be used to access vector elements that are beyond the vector’s fill pointer.