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+'\" t
+.\" Copyright (c) 1990, 1991 Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\" @(#)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
+.\"
+.TH stdio 3 2023-07-30 "Linux man-pages 6.05.01"
+.SH NAME
+stdio \- standard input/output library functions
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.PP
+.BI "FILE *" stdin ;
+.BI "FILE *" stdout ;
+.BI "FILE *" stderr ;
+.fi
+.SH DESCRIPTION
+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.
+.PP
+A stream is associated with an external file (which may be a physical
+device) by
+.I 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
+.I 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
+.BR fgetc (3)
+function; all output takes place as if all characters were written by
+successive calls to the
+.BR fputc (3)
+function.
+.PP
+A file is disassociated from a stream by
+.I 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
+.I FILE
+object is indeterminate after a file is closed (garbage).
+.PP
+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
+.BR 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
+.BR abort (3)
+do not bother about closing files properly.
+.PP
+At program startup, three text streams are predefined and need not be
+opened explicitly:
+.I standard input
+(for reading conventional input),
+.I standard output
+(for writing conventional output), and
+.I standard error
+(for writing diagnostic output).
+These streams are abbreviated
+.IR stdin ,
+.IR stdout ,
+and
+.IR 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 refer to an interactive device.
+.PP
+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
+.BR fflush (3)
+the standard output before going off and computing so that the output will
+appear.
+.PP
+The
+.I stdio
+library is a part of the library
+.B libc
+and routines are automatically loaded as needed by
+.BR cc (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.
+.PP
+The following are defined as macros; these names may not be reused without
+first removing their current definitions with
+.BR #undef :
+.BR BUFSIZ ,
+.BR EOF ,
+.BR FILENAME_MAX ,
+.BR FOPEN_MAX ,
+.BR L_cuserid ,
+.BR L_ctermid ,
+.BR L_tmpnam ,
+.BR NULL ,
+.BR SEEK_END ,
+.BR SEEK_SET ,
+.BR SEEK_CUR ,
+.BR TMP_MAX ,
+.BR clearerr ,
+.BR feof ,
+.BR ferror ,
+.BR fileno ,
+.\" Not on Linux: .BR fropen ,
+.\" Not on Linux: .BR fwopen ,
+.BR getc ,
+.BR getchar ,
+.BR putc ,
+.BR putchar ,
+.BR stderr ,
+.BR stdin ,
+.BR stdout .
+Function versions of the macro functions
+.BR feof ,
+.BR ferror ,
+.BR clearerr ,
+.BR fileno ,
+.BR getc ,
+.BR getchar ,
+.BR putc ,
+and
+.B putchar
+exist and will be used if the macros definitions are explicitly removed.
+.SS List of functions
+.TS
+;
+lb lbx
+l l.
+Function Description
+_
+\fBclearerr\fP(3) T{
+check and reset stream status
+T}
+\fBfclose\fP(3) T{
+close a stream
+T}
+\fBfdopen\fP(3) T{
+stream open functions
+T}
+\fBfeof\fP(3) T{
+check and reset stream status
+T}
+\fBferror\fP(3) T{
+check and reset stream status
+T}
+\fBfflush\fP(3) T{
+flush a stream
+T}
+\fBfgetc\fP(3) T{
+get next character or word from input stream
+T}
+\fBfgetpos\fP(3) T{
+reposition a stream
+T}
+\fBfgets\fP(3) T{
+get a line from a stream
+T}
+\fBfileno\fP(3) T{
+return the integer descriptor of the argument stream
+T}
+\fBfopen\fP(3) T{
+stream open functions
+T}
+\fBfprintf\fP(3) T{
+formatted output conversion
+T}
+\fBfpurge\fP(3) T{
+flush a stream
+T}
+\fBfputc\fP(3) T{
+output a character or word to a stream
+T}
+\fBfputs\fP(3) T{
+output a line to a stream
+T}
+\fBfread\fP(3) T{
+binary stream input/output
+T}
+\fBfreopen\fP(3) T{
+stream open functions
+T}
+\fBfscanf\fP(3) T{
+input format conversion
+T}
+\fBfseek\fP(3) T{
+reposition a stream
+T}
+\fBfsetpos\fP(3) T{
+reposition a stream
+T}
+\fBftell\fP(3) T{
+reposition a stream
+T}
+\fBfwrite\fP(3) T{
+binary stream input/output
+T}
+\fBgetc\fP(3) T{
+get next character or word from input stream
+T}
+\fBgetchar\fP(3) T{
+get next character or word from input stream
+T}
+\fBgets\fP(3) T{
+get a line from a stream
+T}
+\fBgetw\fP(3) T{
+get next character or word from input stream
+T}
+\fBmktemp\fP(3) T{
+make temporary filename (unique)
+T}
+\fBperror\fP(3) T{
+system error messages
+T}
+\fBprintf\fP(3) T{
+formatted output conversion
+T}
+\fBputc\fP(3) T{
+output a character or word to a stream
+T}
+\fBputchar\fP(3) T{
+output a character or word to a stream
+T}
+\fBputs\fP(3) T{
+output a line to a stream
+T}
+\fBputw\fP(3) T{
+output a character or word to a stream
+T}
+\fBremove\fP(3) T{
+remove directory entry
+T}
+\fBrewind\fP(3) T{
+reposition a stream
+T}
+\fBscanf\fP(3) T{
+input format conversion
+T}
+\fBsetbuf\fP(3) T{
+stream buffering operations
+T}
+\fBsetbuffer\fP(3) T{
+stream buffering operations
+T}
+\fBsetlinebuf\fP(3) T{
+stream buffering operations
+T}
+\fBsetvbuf\fP(3) T{
+stream buffering operations
+T}
+\fBsprintf\fP(3) T{
+formatted output conversion
+T}
+\fBsscanf\fP(3) T{
+input format conversion
+T}
+\fBstrerror\fP(3) T{
+system error messages
+T}
+\fBsys_errlist\fP(3) T{
+system error messages
+T}
+\fBsys_nerr\fP(3) T{
+system error messages
+T}
+\fBtempnam\fP(3) T{
+temporary file routines
+T}
+\fBtmpfile\fP(3) T{
+temporary file routines
+T}
+\fBtmpnam\fP(3) T{
+temporary file routines
+T}
+\fBungetc\fP(3) T{
+un-get character from input stream
+T}
+\fBvfprintf\fP(3) T{
+formatted output conversion
+T}
+\fBvfscanf\fP(3) T{
+input format conversion
+T}
+\fBvprintf\fP(3) T{
+formatted output conversion
+T}
+\fBvscanf\fP(3) T{
+input format conversion
+T}
+\fBvsprintf\fP(3) T{
+formatted output conversion
+T}
+\fBvsscanf\fP(3) T{
+input format conversion
+T}
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C89, POSIX.1-2001.
+.SH SEE ALSO
+.BR close (2),
+.BR open (2),
+.BR read (2),
+.BR write (2),
+.BR stdout (3),
+.BR unlocked_stdio (3)