[erlang-questions] Newbie Question about io:format

Hakim Fajardo <>
Wed Feb 22 20:11:17 CET 2017


Thank you,

I understand now.

On Tue, Feb 21, 2017 at 4:42 AM, Dmytro Lytovchenko <
> wrote:

> Because Erlang has no functions with variable amount of arguments (like
> for example in printf C/C++), args to io:format are passed as a list. So
> correct way to call it is:
>
> io:format("Bla ~p~n", [Av1]).
>
> Where ~p is to print any value, also there are more ways to format a
> value, consult the documentation page at http://erlang.org/doc/man/
> io.html#fwrite-1
>
> 2017-02-21 10:15 GMT+01:00 Hakim Fajardo <>:
>
>> First, thank you because this is a great resource.
>>
>> Second, I started writing basic programs every day to improve my Erlang
>> coding. I wrote a simple program that calculates the average of a list of
>> numbers. But I keep getting this error about io:format.
>>
>>
>> prices([]) ->
>>     [],
>>     io:format("List is empty ~n");
>>
>> %% determine number of items in the list to calculate average%%
>>
>> prices(L) when is_list(L) ->
>>   Size = length(L),
>>   Sum1 = lists:sum(L),
>>   Av1 = Sum1 / Size,
>>   io:format("The average equals ~n", Av1).
>>
>>
>> Then..
>>
>> Eshell V8.2  (abort with ^G)
>> 1> L = [1,2,2,2,3,3,4].
>> [1,2,2,2,3,3,4]
>>
>> 2> c(standev).
>> {ok,standev}
>>
>> 3> standev:prices(L).
>> ** exception error: bad argument
>>      in function  io:format/3
>>         called as io:format(<0.50.0>,"The average equals
>> ~n",2.4285714285714284)
>>
>>
>> Why am I getting '**exception error:'?
>>
>> Thank you, I hope this isn't too newbie a question.
>>
>>
>>
>>
>> _______________________________________________
>> erlang-questions mailing list
>> 
>> http://erlang.org/mailman/listinfo/erlang-questions
>>
>>
>
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