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

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John Reye <jononanon@googlemail.com> writes:
> 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!!!

You can't.  This is one of several reasons not to use fgets().

If you're on a POSIXish platform (which includes most Unix derivatives),
you can use getline() instead:

   ssize_t getline(char **buf, size_t *size, FILE *f);

where

 - buf is a pointer to a char * which is either NULL or points to a
   malloc()ed buffer; getline() will malloc() or realloc() as needed.

 - size is a pointer to a size_t which contains the size of the buffer,
   i.e. the size argument from the last malloc() or realloc() call.

 - f is the stream to read from.  I wish they had placed it first in the
   argument list instead of last.

 - the return value is the length of the string (i.e. what strlen()
   would return), or -1 if an error occurred or EOF was reached before
   any data was read.

See also

   http://en.wikibooks.org/wiki/C_Programming/C_Reference/stdio.h/gets

DES
-- 
Dag-Erling Smørgrav - des@des.no
-- 
comp.lang.c.moderated - moderation address: clcm@plethora.net -- you must
have an appropriate newsgroups line in your header for your mail to be seen,
or the newsgroup name in square brackets in the subject line.  Sorry.

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Thread

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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