GNU Info
(libc.info)Closing Streams
Closing Streams
===============
When a stream is closed with `fclose', the connection between the
stream and the file is canceled. After you have closed a stream, you
cannot perform any additional operations on it.
- Function: int fclose (FILE *STREAM)
This function causes STREAM 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 `fclose' function returns
a value of `0' if the file was closed successfully, and `EOF' if
an error was detected.
It is important to check for errors when you call `fclose' to close
an output stream, because real, everyday errors can be detected at
this time. For example, when `fclose' 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.
The function `fclose' is declared in `stdio.h'.
To close all streams currently available the GNU C Library provides
another function.
- Function: int fcloseall (void)
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
`fcloseall' function returns a value of `0' if all the files were
closed successfully, and `EOF' if an error was detected.
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 (Note: Standard Streams) will also be
closed.
The function `fcloseall' is declared in `stdio.h'.
If the `main' function to your program returns, or if you call the
`exit' function (Note: Normal Termination), all open streams are
automatically closed properly. If your program terminates in any other
manner, such as by calling the `abort' function (Note: Aborting a
Program) or from a fatal signal (Note: Signal Handling), 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 Note: Stream Buffering.
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