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From: Andrey Tarasevich <noone@noone.net>
Newsgroups: comp.lang.c
Subject: Re: Buffer contents well-defined after fgets() reaches EOF ?
Date: Sun, 9 Feb 2025 17:22:43 -0800
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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.

-- 
Best regards,
Andrey