Very Computer

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Hi all,

I am not new unix programer. But I having an amazing, to me, problem.

I write a program that read a file serching for to two integer, transform
in float and save into a complex vector. The code is lock like :

   indice = 1;
   while ( !(feof(input)) ) {
     if ( read2int(cdata, input) ) {
        perror(__FILE__);
        return -1;
     }
     vector = realloc(vector, indice*sizeof(complex));
     vector[indice-1] = cdata;
     indice++;
   }

   read2int is just a routine that read to integer, test return of "fread"
function and errno for errors, transform the read integer in float. If
not errors was found this routine returns 0 elsewise -1 is returned.

Me test file have a 1024 pairs of integer, when the 1024-esimo integer pair
is read the while loop is even running.

What is the problem with may code?
Can I substitue the "!feof(input)" by
  if ( ((fread(&intbuff, sizeof(int), 2, input)) == 0) && (errno==0) )?

Any suggestions?

Thank in advance

                                        Hernn

                           Hernn J Cervantes Rodrguez
                           Instituto de Fsica da USP

                           homepage : http://fge.if.usp.br/~hernan/

Quote:> I am not new unix programer. But I having an amazing, to me, problem.
> I write a program that read a file serching for to two integer, transform
> in float and save into a complex vector. The code is lock like :
>    indice = 1;
>    while ( !(feof(input)) ) {
>      if ( read2int(cdata, input) ) {
>         perror(__FILE__);
>         return -1;
>      }
>      vector = realloc(vector, indice*sizeof(complex));
>      vector[indice-1] = cdata;
>      indice++;
>    }
>    read2int is just a routine that read to integer, test return of "fread"
> function and errno for errors, transform the read integer in float. If
> not errors was found this routine returns 0 elsewise -1 is returned.
> Me test file have a 1024 pairs of integer, when the 1024-esimo integer pair
> is read the while loop is even running.
> What is the problem with may code?
> Can I substitue the "!feof(input)" by
>   if ( ((fread(&intbuff, sizeof(int), 2, input)) == 0) && (errno==0) )?
> Any suggestions?

i would suggest this input loop instead:

  while(fread(&intbuff, sizeof(int), 2, input) == 2)
  {
    /* do stuff */
  }

---
"... What with you being his parents and all, I think that you could
be trusted not to shaft him."  -- Robert Chang, rec.games.board

Quote:> I am not new unix programer. But I having an amazing, to me, problem.

Quote:> I write a program that read a file serching for to two integer,
> transform
> in float and save into a complex vector. The code is lock like :

>    indice = 1;
>    while ( !(feof(input)) ) {

feof only tests for whether an end-of-file error _has already occurred_
on a stream.  It is _not_ used for testing when a file is _at_ the end.

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Quote:>>    while ( !(feof(input)) ) {

Quote:>feof only tests for whether an end-of-file error _has already occurred_
>on a stream.  It is _not_ used for testing when a file is _at_ the end.

In other words, for feof() to "predict" end-of-file, it would have
to *be* the fread() function, and the fgets() function, and every
other input-reading function.  In which case, why not just call
fread(), or fgets(), or whichever input function you wanted?

Once fread() fails to read a full set of bytes, a separate feof()
becomes useful: it tests the reason for the failure.  There are
two possible reasons for that failure, namely, error (a read() call
returned -1) or EOF (a read() returned 0).  If you want to distinguish
between these, you need some way to diagnose the "reason for last
input-operation failure".
--
In-Real-Life: Chris Torek, Berkeley Software Design Inc