Accessor char, schar

Syntax:

Arguments and Values:

18.1.0 4string—for char, a string; for schar, a simple string.

index—a valid array index for the string.

character, new-character—a character.

Description:

18.1.0 3char and schar access the element of string specified by index. This is now said in the concept stuff. \param{Index} is an offset from the beginning of \param{string}; indexing is zero-origin.

char ignores fill pointers when accessing elements.

KAB: Implied by "access". \macref{setf} can be used with \funref{char} or \funref{schar} to destructively replace an \term{element} of the \param{string}.

Examples:

 (setq my-simple-string (make-string 6 :initial-element #\A)) → "AAAAAA"
 (schar my-simple-string 4) → #\A
 (setf (schar my-simple-string 4) #\B) → #\B
 my-simple-string → "AAAABA"
 (setq my-filled-string
       (make-array 6 :element-type 'character
                     :fill-pointer 5
                     :initial-contents my-simple-string))
→ "AAAAB"
 (char my-filled-string 4) → #\B
 (char my-filled-string 5) → #\A
 (setf (char my-filled-string 3) #\C) → #\C
 (setf (char my-filled-string 5) #\D) → #\D
 (setf (fill-pointer my-filled-string) 6) → 6
 my-filled-string → "AAACBD"

Affected By:

None.

Exceptional Situations:

None.

See Also:

aref, elt, Section 3.2.1 (Compiler Terminology)

Notes:

 (char s j) ≡ (aref (the string s) j)