[erlang-questions] is this a well written function

[Martin Koroudjiev]

It's perfect, just note that you will get "no function clause" exception
if you pass negative number to the function which is probably desired
result.

Martin

On 2/9/2015 4:11 PM, Roelof Wobben wrote:
> Roelof Wobben schreef op 9-2-2015 om 14:39:
>> sum(End) -> sum_acc(0, 0, End).
>>
>> sum_acc(Acc, _, 0) ->
>>      Acc;
>> sum_acc(Acc, Current, Rem) ->
>>      sum_acc(Acc + Current, Current + 1, Rem - 1). 
>
>
> A new try after some remarks :
>
> -module(sum_recursion).
>
> -export([sum/1]).
>
> % when the number is zero the outcome will also be zero
> sum(0) ->
>   0;
>
> % when a number is greater then 0 , call the helper function.
> sum(End) when End > 0 ->
>   sum_acc(0, End).
>
> % When End is equal to zero all the numbers are added
> sum_acc(Acc, 0) ->
>      Acc;
>
> % when end is not zero there are more numbers to be added.
> sum_acc(Acc, End) ->
>      sum_acc(Acc + End, End - 1).
>
> Roelof
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