CODEWITHSUNDEEP
clojure
hkira1
hkira1

Reputation: 51

Clojure Factorials

(ns factorials)

(defn displayFactorials[number]
    (if (> number 1)
        (do
        (* number (displayFactorials(- number 1))))))

(defn -main []
    (println "To display the factorials,")
    (print " enter the number: ") (flush)
    (let
        [ number (double (read))]
        (println)
        (displayFactorials number)
        (println)
    )
)

I'm writing a factorial program that receives a user input. The program is compiling, bu the result is not printing. Any suggestions on what I should do?

Upvotes: 0

Views: 93

Answers (1)

Alan Thompson
Alan Thompson

Reputation: 29966

You need to make it look like this:

(println (displayFactorials number))

Here is a better formatted version of the program:

(ns demo.core)

(defn displayFactorials
  [number]
  (if (> number 1)
    (* number (displayFactorials (- number 1)))))

(defn -main []
  (println "To display the factorials,")
  (print " enter the number: ") (flush)
  (let [number (double (read))]
    (println
      (displayFactorials number))))

Hint: You also forgot about what to do if the number is equal to one.

Update

See the hint above. Write a unit test in the file test/tst/demo/core.clj like:

(ns tst.demo.core
  (:use demo.core tupelo.test))

(deftest dummy#
  (println :answer (displayFactorials 5)))

Try running lein test and see the exception:

ERROR in (dummy#) (Numbers.java:1068)
Uncaught exception, not in assertion.
expected: nil
  actual: java.lang.NullPointerException: null
 at clojure.lang.Numbers.ops (Numbers.java:1068)
    clojure.lang.Numbers.multiply (Numbers.java:173)
    demo.core$displayFactorials.invokeStatic (core.clj:6)
    demo.core$displayFactorials.invoke (core.clj:3)
    demo.core$displayFactorials.invokeStatic (core.clj:6)
    demo.core$displayFactorials.invoke (core.clj:3)
    demo.core$displayFactorials.invokeStatic (core.clj:6)
    demo.core$displayFactorials.invoke (core.clj:3)
    demo.core$displayFactorials.invokeStatic (core.clj:6)
    demo.core$displayFactorials.invoke (core.clj:3)
    tst.demo.core$fn__18527.invokeStatic (core.clj:11)
    tst.demo.core/fn (core.clj:10)

that should be a BIG clue as to what is missing.

Upvotes: 1

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