stdio — standard input/output library functions
#include <stdio.h> FILE *stdin; FILE *stdout; FILE *stderr;
The standard I/O library provides a simple and efficient buffered stream I/O interface. Input and output is mapped into logical data streams and the physical I/O characteristics are concealed. The functions and macros are listed below; more information is available from the individual man pages.
A stream is associated with an external file (which may be
a physical device) by opening
a file, which may
involve creating a new file. Creating an existing file causes
its former contents to be discarded. If a file can support
positioning requests (such as a disk file, as opposed to a
terminal) then a file position
indicator associated with the stream is
positioned at the start of the file (byte zero), unless the
file is opened with append mode. If append mode is used, it
is unspecified whether the position indicator will be placed
at the start or the end of the file. The position indicator
is maintained by subsequent reads, writes and positioning
requests. All input occurs as if the characters were read by
successive calls to the fgetc(3) function; all
output takes place as if all characters were written by
successive calls to the fputc(3) function.
A file is disassociated from a stream by closing
the file. Output
streams are flushed (any unwritten buffer contents are
transferred to the host environment) before the stream is
disassociated from the file. The value of a pointer to a
FILE
object is indeterminate
after a file is closed (garbage).
A file may be subsequently reopened, by the same or another program execution, and its contents reclaimed or modified (if it can be repositioned at the start). If the main function returns to its original caller, or the exit(3) function is called, all open files are closed (hence all output streams are flushed) before program termination. Other methods of program termination, such as abort(3) do not bother about closing files properly.
At program startup, three text streams are predefined and
need not be opened explicitly — standard input (for reading
conventional input), — standard output (for writing
conventional input), and standard
error (for writing diagnostic output). These
streams are abbreviated stdin
,stdout
and stderr
. When opened, the
standard error stream is not fully buffered; the standard
input and output streams are fully buffered if and only if
the streams do not to refer to an interactive device.
Output streams that refer to terminal devices are always line buffered by default; pending output to such streams is written automatically whenever an input stream that refers to a terminal device is read. In cases where a large amount of computation is done after printing part of a line on an output terminal, it is necessary to fflush(3) the standard output before going off and computing so that the output will appear.
The stdio
library is a part
of the library libc
and routines are automatically loaded as needed by the
compilers cc(1) and pc(1). The SYNOPSIS
sections of the following manual
pages indicate which include files are to be used, what the
compiler declaration for the function looks like and which
external variables are of interest.
The following are defined as macros; these names may not
be re-used without first removing their current definitions
with #undef
:
BUFSIZ
, EOF
, FILENAME_MAX
, FOPEN_MAX
, L_cuserid
, L_ctermid
, L_tmpnam
, NULL
, SEEK_END
, SEEK_SET
, SEE_CUR
, TMP_MAX
, clearerr
, feof
, ferror
,
fileno
, getc
, getchar
, putc
, putchar
, stderr
, stdin
,
stdout
. Function versions of the
macro functions feof
,
ferror
, clearerr
, fileno
, getc
,
getchar
, putc
, and putchar
exist and will be used if the
macros definitions are explicitly removed.
Description
clearerr
check and reset stream status
fclose
close a stream
fdopen
stream open functions
feof
check and reset stream status
ferror
check and reset stream status
fflush
flush a stream
fgetc
get next character or word from input stream
fgetpos
reposition a stream
fgets
get a line from a stream
fileno
return the integer descriptor of the argument stream
fopen
stream open functions
fprintf
formatted output conversion
fpurge
flush a stream
fputc
output a character or word to a stream
fputs
output a line to a stream
fread
binary stream input/output
freopen
stream open functions
fscanf
input format conversion
fseek
reposition a stream
fsetpos
reposition a stream
ftell
reposition a stream
fwrite
binary stream input/output
getc
get next character or word from input stream
getchar
get next character or word from input stream
gets
get a line from a stream
getw
get next character or word from input stream
mktemp
make temporary filename (unique)
perror
system error messages
printf
formatted output conversion
putc
output a character or word to a stream
putchar
output a character or word to a stream
puts
output a line to a stream
putw
output a character or word to a stream
remove
remove directory entry
rewind
reposition a stream
scanf
input format conversion
setbuf
stream buffering operations
setbuffer
stream buffering operations
setlinebuf
stream buffering operations
setvbuf
stream buffering operations
sprintf
formatted output conversion
sscanf
input format conversion
strerror
system error messages
system error messages
system error messages
tempnam
temporary file routines
tmpfile
temporary file routines
tmpnam
temporary file routines
ungetc
un-get character from input stream
vfprintf
formatted output conversion
vfscanf
input format conversion
vprintf
formatted output conversion
vscanf
input format conversion
vsprintf
formatted output conversion
vsscanf
input format conversion
close(2), open(2), read(2), write(2), stdout(3), unlocked_stdio(3)
Copyright (c) 1990, 1991 Regents of the University of California. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3. All advertising materials mentioning features or use of this software must display the following acknowledgement: This product includes software developed by the University of California, Berkeley and its contributors. 4. Neither the name of the University nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. @(#)stdio.3 6.5 (Berkeley) 5/6/91 Converted for Linux, Mon Nov 29 16:07:22 1993, faith@cs.unc.edu Modified, 2001-12-26, aeb |