Skip to main content

division-by-zero

division-by-zero Condition Type

Class Precedence List:

division-by-zero, arithmetic-error, error, serious-condition, condition, t

Description:

The type division-by-zero consists of error conditions that occur because of division by zero.

Expanded Reference: division-by-zero​

Type Hierarchy​

The division-by-zero condition is a subtype of arithmetic-error, which is itself a subtype of error.

(subtypep 'division-by-zero 'arithmetic-error)
=> T
=> T
(subtypep 'division-by-zero 'error)
=> T
=> T

Handling Division by Zero​

Use handler-case to catch division-by-zero errors and provide a fallback value or alternative behavior.

(handler-case (/ 10 0)
  (division-by-zero ()
    :infinity))
=> :INFINITY

(handler-case (/ 1 0)
  (division-by-zero (c)
    (format nil "Cannot divide ~A by ~A"
            (first (arithmetic-error-operands c))
            (second (arithmetic-error-operands c)))))
=> "Cannot divide 1 by 0"

Safe Division Utility​

A common pattern is to write a safe division function that returns a default value instead of signaling an error.

(defun safe-divide (a b &optional (default 0))
  (handler-case (/ a b)
    (division-by-zero () default)))

(safe-divide 10 3)
=> 10/3
(safe-divide 10 0)
=> 0
(safe-divide 10 0 :nan)
=> :NAN

Float vs Integer Division by Zero​

Depending on the implementation, division of a float by zero may signal division-by-zero or may return an IEEE infinity. Integer division by zero always signals.

;; Integer division always signals
(handler-case (/ 1 0)
  (division-by-zero () :caught))
=> :CAUGHT

;; Float behavior is implementation-dependent
(handler-case (/ 1.0 0.0)
  (division-by-zero () :caught))
=> :CAUGHT