The "loop and a half"

[Chris Angelico]

On Thu, Oct 5, 2017 at 10:26 PM, bartc <bc at freeuk.com> wrote:
> On 05/10/2017 12:09, Chris Angelico wrote:
>>
>> On Thu, Oct 5, 2017 at 9:56 PM, bartc <bc at freeuk.com> wrote:
>>>
>>> This doesn't make sense. For interactive use, you wouldn't bother testing
>>> for eof, as you'd be testing the eof status of the keyboard.
>>
>>
>> You mean the way heaps and heaps of Unix programs work, processing
>> until EOF of stdin? Yeah, totally makes no sense, man, no sense at
>> all.
>
>
> Out of the hundreds, perhaps thousands of such input loops I must have
> written, how many needed to test EOF? Hmm, somewhere around zero I think.
>
> Oh hang on, I wasn't using Unix; does that make a difference?
>
> If you're referring to the ability to redirect stdin so that input can come
> from a file as well as from a live keyboard, then you're doing file
> handling; it's NOT interactive.

How would you write a sort program? How would you tell it that you're
done entering data?

And yes, I have used sort(1) interactively, with no redirection whatsoever.

ChrisA