On 5/3/20 8:40 am, brainpower wrote:
> Am 04.03.20 um 23:32 schrieb brainpower:
>> Hi!
>>
>> Am 04.03.20 um 22:29 schrieb Anatol Pomozov:
>>> On Wed, Mar 4, 2020 at 12:39 PM Anatol Pomozov <anatol.pomo...@gmail.com>
>>> wrote:
>>>> + } else if(strcmp(key, "ConcurrentDownloadStreams") == 0) {
>>>> + /* TODO: what is the best way to handle int
>>>> conversion errors? */
>>>> + config->concurrent_download_streams = atoi(value);
>>>
>>> Here is a question I have. What is the best way to handle int
>>> conversion errors for this option?
>>>
>>
>> I'd recommend strtol() [1] over atoi() any time.
>> It makes it a lot easier to get error handling right, well, in most cases
>> actually possible at all!
>>
>> I do not know of any way to differentiate between a valid "0" input and the
>> error case with atoi().
>> There is no way to detect if the input was out of range, atoi() just gives
>> some undefined value.
>> (The only valid use case for atoi() I might find acceptable would be if you
>> can be *absolutely* sure the input is a valid int. e.g. validate before
>> passing to atoi)
>>
>>
>> With strtol() do the following:
>>
>> 1. Call strol()
>> 2. Check if *end is NULL, if it is not, parsing was aborted at the position
>> *end points to
>
> Sorry.
> I messed up and misread the documentation here. The first part of the above
> is incorrect.
>
> You'll have to check str != end, where str is the first pointer passed to
> strtol and end the second.
>
>
>> 3. Check errno for ERANGE, it gets set if the integer given does not fit
>> into a long
>> 4. Now use the number. Check range again, if you want to downcast the long
>> to int.
>>
>> [1]: https://en.cppreference.com/w/c/string/byte/strtol
>>
man strtol has an example usage program, and provides instuctions on how
to check for "0" from input vs error. For pacman, that would likely be
considered an error anyway.
A
