Muco
Hello, everyone, I’m new to Elixir I’m reading a book entitled Phoenix in Action I’m on its second chapter where the author introduces to Elixir but I’m facing this error when I run it into the Elixir shell. This is here:
iex(5)> Fizzbuzz.go(1, 100)
** (CondClauseError) no cond clause evaluated to a truthy value
(fizzbuzz 0.1.0) lib/fizzbuzz.ex:11: Fizzbuzz.show_results/1
(elixir 1.10.1) lib/enum.ex:789: anonymous fn/3 in Enum.each/2
(elixir 1.10.1) lib/enum.ex:3371: Enum.reduce_range_inc/4
(elixir 1.10.1) lib/enum.ex:2116: Enum.each/2
And the code is here:
defmodule Fizzbuzz do
def go(minNumber, maxNumber) do
Enum.each(minNumber..maxNumber, fn number -> show_results(number) end)
end
def show_results(number) do
# IO.puts(number)
cond do
rem(number, 3) == 0 && rem(number, 5) == 0 -> IO.puts("FizzBuzz")
rem(number, 3) == 0 -> IO.puts("Fizz")
rem(number, 5) == 0 -> IO.puts("buzz")
end
end
end
But in the show_results function when I just add IO.puts(number) only I can see them in the console. I need your help, please.
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kip
The message is telling you that there are no conditions within the
condexpression that evaluate totruthy. What should aconddo if no conditions are met? it raises an exceptionThe usual approach is to add a final condition that is guaranteed to evaluate to a
truthyvalue. Oftentrue. So:Muco
Thank you @kip for your response.
The thing that I’m not understanding is why there’s no truthy evaluated as I can see I have numbers from 1 to 100
Muco
Aah!! I actually got it so it means if it encounters nothing evaluated it will just stop the program and raise the exception ? Thank you again @kip
ityonemo
exactly. Also just be careful, the catch-all for
condistrue, and the catch-all forcaseis_(or any variable), It’s easy to get confused if you refactor one to the other.chrisdel101
I had this same question. The first run of
condhad no truthy values so gave an error. Adding a default end condition using thetrue -> "do stuff"solved it.