Standards
| Standards / Extensions |
C or C++ |
Dependencies |
|---|
ISO C
POSIX.1
XPG4
XPG4.2
C99
Single UNIX Specification, Version 3
|
both |
|
Format
#include <stdio.h>
int fclose(FILE *stream);
General description
Flushes
a stream, and then closes the file associated with that stream. Afterwards,
the function releases any buffers associated with the stream. To flush means
that unwritten buffered data is written to the file, and unread buffered
data is discarded.
A
pointer to a closed file cannot be used
as an input value to the freopen() function.
Notes: - The storage pointed to by the FILE pointer is freed by the fclose()
function. An attempt to use the FILE pointer to a closed file is not
valid. This restriction is true even when fclose() fails.
- If an application has locked a (FILE *) object (with flockfile()
or ftrylockfile()), it is responsible for relinquishing the locked
(FILE *) object (with funlockfile()) before calling fclose(). Failure
to relinquish a locked (FILE *) object may cause deadlock (or looping).
Returned value
If successful closing the
stream, fclose() returns 0.
If a failure occurs in flushing
buffers or in outputting data, fclose() returns EOF. An attempt will
still be made to close the file.
Special behavior for XPG4
fclose()
sets errno to one of the following values:
- Error Code
- Description
- EAGAIN
- The O_NONBLOCK flag is set and output cannot be written immediately.
- EBADF
- The underlying file descriptor is not valid.
- EFBIG
- Writing to the output file would exceed the maximum file size
or the process's file size supported by the implementation.
- EINTR
- The fclose() function was interrupted by a signal before it had
written any output.
- EIO
- The process is in a background process group and is attempting
to write to its controlling terminal, but TOSTOP (defined in the termio.h
include file) is set, the process is neither ignoring nor blocking
SIGTTOU signals, and the process group of the process is orphaned.
- ENOSPC
- There is no free space left on the output device
- ENXIO
- A request was made of a nonexistent device, or the request was
outside the device.
- EPIPE
- fclose() is trying to write to a pipe or FIFO that is not open
for reading by any process. This error also generates a SIGPIPE signal.
Example
/* This example opens a file myfile.dat for reading as a stream and then
closes the file.
*/
#include <stdio.h>
int main(void)
{
FILE *stream;
stream = fopen("myfile.dat", "r");
⋮
if (fclose(stream)) /* Close the stream. */
printf("fclose error\n");
}