CODEWITHSUNDEEP
lispcommon-lisp
Florin
Florin

Reputation: 29

Report error in LISP

I have this function that convert a number into a certain base.I want to report an error if the base I introduce is greater than 9 and smaller than 2 but I dont know. Can you help me please?

(defun zecb (number base)
  (write-to-string number :base base))

Upvotes: 0

Views: 98

Answers (4)

MASL
MASL

Reputation: 949

If what you want is printing an error, you can use one of the write/print function available (see Output to character streams).

Example:

(defun zecb (nb base) 
  "Test"
  (if (or (< nb 2) (> nb 9))
      (princ "Number Not in range")
      (* nb base)))

Upvotes: 0

Rainer Joswig
Rainer Joswig

Reputation: 139321

CL-USER 99 > (defun test (n)
               (check-type n (integer 2 9))
               n)
TEST

CL-USER 100 > (test 2)
2

CL-USER 101 > (test 9)
9

CL-USER 102 > (test 10)

Error: The value 10 of N is not of type (INTEGER 2 9).

Upvotes: 5

Daniel Jour
Daniel Jour

Reputation: 16156

Based on the condition system that coredump already mentioned there's also an assert macro that is part of Common Lisp. Try the following in your REPL:

(defun divide (num denom)
  (assert (not (= 0 denom))
          (denom)
          "Attempted to divide ~a by zero, use a different denominator!" num)
  (/ num denom))

(divide 42 0)

(Non-interactive example)

Upvotes: 4

sheikh_anton
sheikh_anton

Reputation: 3452

What do you mean by "report error"? If you mean something like throwing an exception in another languages, error may sute your needs:

(error "Base must be between 2 and 9")

Read more about common lisp conditions and handlers, if you need something more sufisticated than simple-error.

Upvotes: 2

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