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Re: no error by fscanf on reading from output file

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On 2011-10-30, V.Subramanian, India <subramanian100in@yahoo.com> wrote:
>         // opened in 'write' mode
>         if (fscanf(fp, "%d%d", &a, &b) == 2)
>         {
>                 fprintf(stdout,
>                         "a = %d, b= %d\n",
>                         a,
>                         b);
>                 fflush(stdout);
>                 fclose(fp);
>                 return EXIT_SUCCESS;
>         }
>
> [snip]
>
> In this program I open a file 'data.txt' in 'write' mode.
> Subsequently, I write something into this file. Then I read
> from this file using 'fscanf'. This operation should fail.

fscanf does fail (this can be detected by observing that it returns -1).
But fscanf does not read anything from fp (it isn't allowed to
because fp is not in 'read' mode), nothing happens to
the state of fp.

> But when I test the error indicator for the stream by
> calling 'ferror(fp)', the statements inside the
>         if (ferror(fp))
>         {
>          }
> are NOT executed.
> Does this mean that error inidcator for the stream is not set
> by 'fscanf' ? Isn't the operation 'reading from a file
> opened in "write" mode' an error ?

The operation never happes, the stream is not touched.

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no error by fscanf on reading from output file "V.Subramanian, India" <subramanian100in@yahoo.com> - 2011-10-29 23:59 -0700
  Re: no error by fscanf on reading from output file Ian Collins <ian-news@hotmail.com> - 2011-10-30 20:19 +1300
    Re: no error by fscanf on reading from output file Ike Naar <ike@iceland.freeshell.org> - 2011-10-30 08:18 +0000
      Re: no error by fscanf on reading from output file Ian Collins <ian-news@hotmail.com> - 2011-10-30 21:23 +1300
        Re: no error by fscanf on reading from output file Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-10-30 08:11 -0400
          Re: no error by fscanf on reading from output file Ian Collins <ian-news@hotmail.com> - 2011-10-31 07:38 +1300
            Re: no error by fscanf on reading from output file Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-10-30 19:40 +0000
              Re: no error by fscanf on reading from output file Ian Collins <ian-news@hotmail.com> - 2011-10-31 08:50 +1300
  Re: no error by fscanf on reading from output file "V.Subramanian, India" <subramanian100in@yahoo.com> - 2011-10-30 00:01 -0700
  Re: no error by fscanf on reading from output file Ike Naar <ike@iceland.freeshell.org> - 2011-10-30 08:39 +0000
  Re: no error by fscanf on reading from output file Carlo Dapor <catull@gmail.com> - 2011-10-30 19:16 -0700
    Re: no error by fscanf on reading from output file Ian Collins <ian-news@hotmail.com> - 2011-10-31 15:50 +1300
      Re: no error by fscanf on reading from output file "V.Subramanian, India" <subramanian100in@yahoo.com> - 2011-10-30 22:55 -0700
        Re: no error by fscanf on reading from output file pacman@kosh.dhis.org (Alan Curry) - 2011-10-31 07:14 +0000
          Re: no error by fscanf on reading from output file Ian Collins <ian-news@hotmail.com> - 2011-10-31 20:56 +1300
          Re: no error by fscanf on reading from output file Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-10-31 15:43 +0000
        Re: no error by fscanf on reading from output file Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-10-31 01:35 -0700
          Re: no error by fscanf on reading from output file Keith Thompson <kst-u@mib.org> - 2011-10-31 13:46 -0700
    Re: no error by fscanf on reading from output file Ike Naar <ike@iceland.freeshell.org> - 2011-10-31 07:02 +0000

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