.\" Copyright (c) 1980 Regents of the University of California..\" All rights reserved.  The Berkeley software License Agreement.\" specifies the terms and conditions for redistribution..\".\"	@(#)stdio.3s	6.2 (Berkeley) 5/13/86.\".TH STDIO 3 "May 13, 1986".UC 4.SH NAMEstdio \- standard buffered input/output package.SH SYNOPSIS.nf.ft B#include <stdio.h>FILE *stdin;FILE *stdout;FILE *stderr;.ft R.fi.SH DESCRIPTIONThe functions in the standard I/O library constitute a user-level bufferingscheme.  The in-line macros.B getcand.BR  putc (3)handle characters quickly.  The higher level routines.BR gets ,.BR fgets ,.BR scanf ,.BR fscanf ,.BR fread ,.BR puts ,.BR fputs ,.BR printf ,.BR fprintf ,.BR fwriteall use.B getcand.BR putc ;they can be freely intermixed..PPA file with associated buffering is called a.IR stream ,and is declared to be a pointer to a defined type.SM.BR FILE ..BR  Fopen (3)creates certain descriptive data for a streamand returns a pointer to designate the stream in all further transactions.There are three normally open streams with constant pointers declared inthe include file and associated with the standard open files:.TP 10n.B stdinstandard input file.br.ns.TP.B stdoutstandard output file.br.ns.TP.B stderrstandard error file.PPA constant `pointer'.SM.B NULL(0)designates no stream at all..PPAn integer constant.SM.B EOF(\-1) is returned upon end of file or error by integer functions thatdeal with streams..PPAny routine that uses the standard input/output packagemust include the header file.RI < stdio.h >of pertinent macro definitions.The functions and constants mentioned in the standard I/O manual pagesare declared in the include file and need no further declaration.The constants, and the following `functions' areimplemented as macros; redeclaration of these names is perilous:.BR clearerr ,.BR getc ,.BR getchar ,.BR putc ,.BR putchar ,.BR feof ,.BR ferror ,.BR fileno ..SH "SEE ALSO".BR open (2),.BR close (2),.BR read (2),.BR write (2),.BR fclose (3),.BR ferror (3),.BR fopen (3),.BR fread (3),.BR fseek (3),.BR getc (3),.BR gets (3),.BR printf (3),.BR putc (3),.BR puts (3),.BR scanf (3),.BR setbuf (3),.BR ungetc (3)..SH DIAGNOSTICSThe value.SM.B EOFis returned uniformly to indicate that a.SM.B FILEpointer has not been initialized with.BR fopen ,input (output) has been attempted on an output (input) stream, or a.SM.B FILEpointer designates corrupt or otherwise unintelligible.SM.B FILEdata..PPFor purposes of efficiency, this implementation of the standard libraryhas been changed to line buffer output to a terminal by default and attemptsto do this transparently by flushing the output whenever a .BR read (2)from the standard input is necessary.  This is almost always transparent,but may cause confusion or malfunctioning of programs which usestandard i/o routines but use.BR read (2)themselves to read from the standard input..PPIn cases where a large amount of computation is done after printingpart 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 outputwill appear..SH BUGSThe standard buffered functions do not interact well with certain otherlibrary and system functions, especially \fBfork\fP and \fBabort\fP..SH "LIST OF FUNCTIONS".sp 2.nf.ta \w'setlinebuf'u+2n +\w'setbuf(3)'u+10n\fBName\fP	\fBAppears on Page\fP	\fBDescription\fP.ta \w'setlinebuf'u+4n +\w'setbuf(3)'u+4n.sp 5pclearerr	ferror(3)	stream status inquiriesfclose	fclose(3)	close or flush a streamfdopen	fopen(3)	open a streamfeof	ferror(3)	stream status inquiriesferror	ferror(3)	stream status inquiriesfflush	fclose(3)	close or flush a streamfgetc	getc(3)	get character or word from streamfgets	gets(3)	get a string from a streamfileno	ferror(3)	stream status inquiriesfopen	fopen(3)	open a streamfprintf	printf(3)	formatted output conversionfputc	putc(3)	put character or word on a streamfputs	puts(3)	put a string on a streamfread	fread(3)	buffered binary input/outputfreopen	fopen(3)	open a streamfscanf	scanf(3)	formatted input conversionfseek	fseek(3)	reposition a streamftell	fseek(3)	reposition a streamfwrite	fread(3)	buffered binary input/outputgetc	getc(3)	get character or word from streamgetchar	getc(3)	get character or word from streamgets	gets(3)	get a string from a streamgetw	getc(3)	get character or word from streamprintf	printf(3)	formatted output conversionputc	putc(3)	put character or word on a streamputchar	putc(3)	put character or word on a streamputs	puts(3)	put a string on a streamputw	putc(3)	put character or word on a streamrewind	fseek(3)	reposition a streamscanf	scanf(3)	formatted input conversionsetbuf	setbuf(3)	assign buffering to a streamsetvbuf	setbuf(3)	assign buffering to a streamsnprintf	printf(3)	formatted output conversionsprintf	printf(3)	formatted output conversionsscanf	scanf(3)	formatted input conversionungetc	ungetc(3)	push character back into input streamvfprintf	printf(3)	formatted output conversionvfscanf	scanf(3)	formatted input conversionvprintf	printf(3)	formatted output conversionvscanf	scanf(3)	formatted input conversionvsnprintf	printf(3)	formatted output conversionvsprintf	printf(3)	formatted output conversionvsscanf	scanf(3)	formatted input conversion.fi