FOPEN(3S) FOPEN(3S)
NAME
fopen, freopen, fdopen, fclose, fflush - open, close, or
flush a stream
SYNOPSIS
#include <stdio.h>
FILE *fopen(filename, type)
char *filename, *type;
FILE *freopen(filename, type, stream)
char *filename, *type;
FILE *stream;
FILE *fdopen(fildes, type)
char *type;
int fclose(stream)
FILE *stream;
int fflush(stream)
FILE *stream;
DESCRIPTION
Fopen opens the file named by filename and associates a
stream with it. Fopen returns a pointer to be used to iden-
tify the stream in subsequent operations.
Type is a character string having one of the following val-
ues:
"r" open for reading
"w" create for writing
"r+w"
"w+r" open for reading and writing
"a" append: open for writing at end of file, or create for writing
Freopen substitutes the named file in place of the open
stream. It returns the original value of stream. The origi-
nal stream is closed. Freopen is typically used to attach
the preopened constant names `stdin', `stdout' and `stderr'
to specified files.
Fdopen associates a stream with a file descriptor. The type
of the stream must agree with the mode of the open file.
Fclose causes any buffers for the named stream to be emp-
tied, and the file to be closed. Buffers allocated by the
standard input/output system are freed.
Fclose is performed automatically upon calling exit(3).
FOPEN(3S) FOPEN(3S)
Fflush causes any buffered data for the named output stream
to be written to that file. The stream remains open.
SEE ALSO
open(2), popen(3), stdio(3), ferror(3)
DIAGNOSTICS
Fopen and freopen return NULL if filename cannot be
accessed.
Fclose and fflush return EOF if stream is not associated
with a file, or if buffered data cannot be transferred to
that file.