Re: Buffer contents well-defined after fgets() reaches EOF ?

Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:

On 09.02.2025 16:27, Andrey Tarasevich wrote:

[...]

Say, what do you want to see as "the
last line" in a file that ends with
 
  abracadabra\n<EOF here>
 
?
 
Is "abracadabra" the last line? Or is the last line supposed to be empty
in this case?

>
If "\n" is a string literal (2 characters, '\' and 'n') then it's an
incomplete line (as to my standards), if it's meant as a <LF> control
character then it's complete. (Similar with <CR> on old Apple/Macs and
<CR><LF> on DOS-alike systems.)

It seems obvious to me that Andrey intended the \n to be a new-line
character (which is almost always LF in modern C implementations).

Here's (some of) what the C standard says about text streams:

    A text stream is an ordered sequence of characters composed into
    lines, each line consisting of zero or more characters plus a
    terminating new-line character. Whether the last line requires
    a terminating new-line character is implementation-defined.

For an implementation that *doesn't* require a new-line on the
last line, a stream without a trailing new-line is valid.  For an
implementation that *does* require it, such a stream is invalid,
and a program that attempts to process it can have undefined behavior.

Most modern implementations don't require that trailing new-line.
For example, `echo -n hello > hello.txt` creates a valid text file.
Of course a C program that deals with text files can impose any
additional restrictions its author likes.

The above describes how a text stream looks to a C program.  The
external representation can be quite different, with transformations
to map between them.  The most common such transformation is
mapping the DOS/Windows CR-LF line terminator to LF on input, and
vice versa on output.  Or the external representation might store
each line as a fixed-length character sequence padded with spaces.

--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */