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array-total-size

array-total-size Function

Syntax:

array-total-size array → size

Arguments and Values:

array—an array.

size—a non-negative integer .

Description:

Returns the array total size of the array.

Examples:

(array-total-size (make-array 4)) → 4 
(array-total-size (make-array 4 :fill-pointer 2)) → 4 
(array-total-size (make-array 0)) → 0 
(array-total-size (make-array ’(4 2))) → 8 
(array-total-size (make-array ’(4 0))) → 0 
(array-total-size (make-array ’())) → 1

Exceptional Situations:

Should signal an error of type type-error if its argument is not an array.

See Also:

make-array, array-dimensions

Notes:

If the array is a vector with a fill pointer , the fill pointer is ignored when calculating the array total size.

Since the product of no arguments is one, the array total size of a zero-dimensional array is one.

(array-total-size x)

≡ (apply #’* (array-dimensions x))

≡ (reduce #’* (array-dimensions x))

Expanded Reference: array-total-size​

Basic Usage​

array-total-size returns the total number of elements in an array, which is the product of all its dimensions.

(array-total-size (make-array 5))
=> 5

(array-total-size (make-array '(3 4)))
=> 12

(array-total-size (make-array '(2 3 4)))
=> 24

Edge Cases: Zero and Zero-Dimensional Arrays​

An array with any dimension of size 0 has total size 0. A zero-dimensional array (no dimensions) has total size 1 because the product of no numbers is 1.

(array-total-size (make-array 0))
=> 0

(array-total-size (make-array '(5 0)))
=> 0

;; Zero-dimensional array: product of zero dimensions = 1
(array-total-size (make-array '()))
=> 1

Fill Pointer Is Ignored​

array-total-size returns the allocated size, ignoring any fill pointer.

(let ((v (make-array 20 :fill-pointer 5)))
  (list (length v)              ; respects fill pointer
        (array-total-size v)))  ; actual allocated size
=> (5 20)

Equivalence to Product of Dimensions​

array-total-size is equivalent to multiplying the values returned by array-dimensions.

(let ((a (make-array '(4 5 6))))
  (= (array-total-size a)
     (apply #'* (array-dimensions a))))
=> T