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Re: fgets - design deficiency: no efficient way of finding last character read

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On 2012-04-23, John Reye <jononanon@googlemail.com> wrote:
> Hello,
>
> The last character read from fgets(buf, sizeof(buf), inputstream) is:
> '\n'
> OR
> any character x, when no '\n' was encountered in sizeof(buf)-1
> consecutive chars, or when x is the last char of the inputstream
>
> ***How can one EFFICIENTLY determine if the last character is '\n'??
> "Efficiently" means: don't use strlen!!!

intialise the last character in the buffer with \0 before calling fgets
if it gets changed to anything other than \n then an incomplete line
was read.

OTOH strlen is much faster than most I/O so does it really matter?

> A well-designed fgets function should return the length of characters
> read, should it not??
>
> Please surprise me, that there is a way of efficiently determining the
> number of characters read. ;)
>
> I've thought of ftell, but I think that does not work with stdin.

yeah, it works with files, stdin is usually not a file.

> Because right now, I think that fgets really seems useless.
> Why is the standard C library so inefficient?

what's the point of using fgets on stdin anywaqy

> Do I really have to go about designing my own library? ;)
>
> Thanks for tipps and pointers

libreadline  (GPL)
libgettext   (BSD)
getline      (posix.1 2008)

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fgets - design deficiency: no efficient way of finding last character read John Reye <jononanon@googlemail.com> - 2012-04-23 08:33 -0500
  Re: fgets - design deficiency: no efficient way of finding last character read Barry Schwarz <schwarzb@dqel.com> - 2012-04-30 21:57 -0500
  Re: fgets - design deficiency: no efficient way of finding last character read Jasen Betts <jasen@xnet.co.nz> - 2012-04-30 21:59 -0500
  Re: fgets - design deficiency: no efficient way of finding last character read James Kuyper <jameskuyper@verizon.net> - 2012-04-30 21:57 -0500
  Re: fgets - design deficiency: no efficient way of finding last character read Dag-Erling Smørgrav <des@des.no> - 2012-04-30 21:57 -0500
  Re: fgets - design deficiency: no efficient way of finding last character read Thomas Richter <thor@math.tu-berlin.de> - 2012-04-30 21:58 -0500
  Re: fgets - design deficiency: no efficient way of finding last character read John Reye <jononanon@googlemail.com> - 2012-04-30 21:59 -0500

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