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| <h3 class="section">12.4 Closing Streams</h3> |
| |
| <p><a name="index-closing-a-stream-940"></a>When a stream is closed with <code>fclose</code>, the connection between the |
| stream and the file is canceled. After you have closed a stream, you |
| cannot perform any additional operations on it. |
| |
| <!-- stdio.h --> |
| <!-- ISO --> |
| <div class="defun"> |
| — Function: int <b>fclose</b> (<var>FILE *stream</var>)<var><a name="index-fclose-941"></a></var><br> |
| <blockquote><p>This function causes <var>stream</var> to be closed and the connection to |
| the corresponding file to be broken. Any buffered output is written |
| and any buffered input is discarded. The <code>fclose</code> function returns |
| a value of <code>0</code> if the file was closed successfully, and <code>EOF</code> |
| if an error was detected. |
| |
| <p>It is important to check for errors when you call <code>fclose</code> to close |
| an output stream, because real, everyday errors can be detected at this |
| time. For example, when <code>fclose</code> writes the remaining buffered |
| output, it might get an error because the disk is full. Even if you |
| know the buffer is empty, errors can still occur when closing a file if |
| you are using NFS. |
| |
| <p>The function <code>fclose</code> is declared in <samp><span class="file">stdio.h</span></samp>. |
| </p></blockquote></div> |
| |
| <p>To close all streams currently available the GNU C Library provides |
| another function. |
| |
| <!-- stdio.h --> |
| <!-- GNU --> |
| <div class="defun"> |
| — Function: int <b>fcloseall</b> (<var>void</var>)<var><a name="index-fcloseall-942"></a></var><br> |
| <blockquote><p>This function causes all open streams of the process to be closed and |
| the connection to corresponding files to be broken. All buffered data |
| is written and any buffered input is discarded. The <code>fcloseall</code> |
| function returns a value of <code>0</code> if all the files were closed |
| successfully, and <code>EOF</code> if an error was detected. |
| |
| <p>This function should be used only in special situations, e.g., when an |
| error occurred and the program must be aborted. Normally each single |
| stream should be closed separately so that problems with individual |
| streams can be identified. It is also problematic since the standard |
| streams (see <a href="Standard-Streams.html#Standard-Streams">Standard Streams</a>) will also be closed. |
| |
| <p>The function <code>fcloseall</code> is declared in <samp><span class="file">stdio.h</span></samp>. |
| </p></blockquote></div> |
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| <p>If the <code>main</code> function to your program returns, or if you call the |
| <code>exit</code> function (see <a href="Normal-Termination.html#Normal-Termination">Normal Termination</a>), all open streams are |
| automatically closed properly. If your program terminates in any other |
| manner, such as by calling the <code>abort</code> function (see <a href="Aborting-a-Program.html#Aborting-a-Program">Aborting a Program</a>) or from a fatal signal (see <a href="Signal-Handling.html#Signal-Handling">Signal Handling</a>), open streams |
| might not be closed properly. Buffered output might not be flushed and |
| files may be incomplete. For more information on buffering of streams, |
| see <a href="Stream-Buffering.html#Stream-Buffering">Stream Buffering</a>. |
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