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<h4 class="subsection">14.2.18 End of File and Errors</h4>
<p>Once a file has been opened its status can be acquired. As an example
the <code>feof</code> functions determines if the end of the file has been
reached. This can be very useful when reading small parts of a file
at a time. The following example shows how to read one line at a time
from a file until the end has been reached.
<pre class="example"> filename = "myfile.txt";
fid = fopen (filename, "r");
while (! feof (fid) )
text_line = fgetl (fid);
endwhile
fclose (fid);
</pre>
<p class="noindent">Note that in some situations it is more efficient to read the entire
contents of a file and then process it, than it is to read it line by
line. This has the potential advantage of removing the loop in the
above code.
<!-- file-io.cc -->
<p><a name="doc_002dfeof"></a>
<div class="defun">
— Built-in Function: <b>feof</b> (<var>fid</var>)<var><a name="index-feof-805"></a></var><br>
<blockquote><p>Return 1 if an end-of-file condition has been encountered for a given
file and 0 otherwise. Note that it will only return 1 if the end of the
file has already been encountered, not if the next read operation will
result in an end-of-file condition.
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<p class="noindent"><strong>See also:</strong> <a href="doc_002dfread.html#doc_002dfread">fread</a>, <a href="doc_002dfopen.html#doc_002dfopen">fopen</a>, <a href="doc_002dfclose.html#doc_002dfclose">fclose</a>.
</p></blockquote></div>
<!-- file-io.cc -->
<p><a name="doc_002dferror"></a>
<div class="defun">
— Built-in Function: <b>ferror</b> (<var>fid</var>)<var><a name="index-ferror-806"></a></var><br>
<blockquote><p>Return 1 if an error condition has been encountered for a given file
and 0 otherwise. Note that it will only return 1 if an error has
already been encountered, not if the next operation will result in an
error condition.
</p></blockquote></div>
<!-- file-io.cc -->
<p><a name="doc_002dfclear"></a>
<div class="defun">
— Built-in Function: <b>fclear</b> (<var>fid</var>)<var><a name="index-fclear-807"></a></var><br>
<blockquote><p>Clear the stream state for the specified file.
</p></blockquote></div>
<!-- file-io.cc -->
<p><a name="doc_002dfreport"></a>
<div class="defun">
— Built-in Function: <b>freport</b> ()<var><a name="index-freport-808"></a></var><br>
<blockquote><p>Print a list of which files have been opened, and whether they are open
for reading, writing, or both. For example,
<pre class="example"> freport ()
-| number mode name
-|
-| 0 r stdin
-| 1 w stdout
-| 2 w stderr
-| 3 r myfile
</pre>
</blockquote></div>
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distrib
>
Mandriva
>
2010.0
>
i586
>
media
>
contrib-release
>
by-pkgid
>
3e60ff9d4d6f58c8fbd17208f14089fa
>
files
>
161
