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From: Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups: comp.lang.c
Subject: Re: Buffer contents well-defined after fgets() reaches EOF ?
Date: Thu, 13 Feb 2025 07:14:28 -0800
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Michael S <already5chosen@yahoo.com> writes:

> On Sun, 9 Feb 2025 17:22:43 -0800
> Andrey Tarasevich <noone@noone.net> wrote:
>
>> On Sun 2/9/2025 5:06 PM, Andrey Tarasevich wrote:
>>
>>> On Sun 2/9/2025 3:52 PM, Lawrence D'Oliveiro wrote:
>>>
>>>> On Sat, 8 Feb 2025 23:12:44 -0800, Andrey Tarasevich wrote:
>>>>
>>>>> If `fgets` reads nothing (instant end-of-file), the entire buffer
>>>>> remains untouched.
>>>>
>>>> You mean, only a single null byte gets written.
>>>
>>> No.  The buffer is not changed at all in such case.
>>
>> ... which actually raises an interesting quiz/puzzle/question:
>>
>>    Under what circumstances `fgets` is expected to return an empty
>> string?  (I.e. set the [0] entry of the buffer to '\0' and return
>> non-null)?
>>
>> The only answer I can see right away is:
>>
>>    When one calls it as `fgets(buffer, 1, file)`, i.e. asks it to
>> read 0 characters.
>>
>> This is under assumption that asking `fgets` to read 0 characters is
>> supposed to prevent it from detecting end-of-file condition or I/O
>> error condition.  One can probably do some nitpicking at the current
>> wording... but I believe the above is the intent.
>
> fgets() is one of many poorly defined standard library functions
> inherited from early UNIX days.  [...]

What about the fgets() function do you think is poorly defined?

Second question: by "poorly defined" do you mean "defined
wrongly" or "defined ambiguously" (or both)?