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STDIO(3)		   Linux Programmer's Manual		      STDIO(3)

NAME
       stdio - standard	input/output library functions

SYNOPSIS
       #include	<stdio.h>

       FILE *stdin;
       FILE *stdout;
       FILE *stderr;

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 func-
       tions 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.  Cre-
       ating  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, the posi-
       tion indicator will be placed the end-of-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
       read 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 reposi-
       tioned 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 stan-
       dard 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 auto-
       matically loaded	as needed by the compilers cc(1) and pc(1).  The  SYN-
       OPSIS  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,
       fropen,	fwopen,	 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.

LIST OF	FUNCTIONS
       Function	 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	 check and reset stream	status

       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

       fropen	 open a	stream

       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	file name (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

       sys_errlist
		 system	error messages

       sys_nerr	 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

CONFORMING TO
       The stdio library conforms to ANSI X3.159-1989 (``ANSI C'').

SEE ALSO
       open(2),	close(2), read(2), write(2), stdout(3)

				  2001-12-26			      STDIO(3)

NAME | SYNOPSIS | DESCRIPTION | LIST OF FUNCTIONS | CONFORMING TO | SEE ALSO

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