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STDIO(3)	       FreeBSD Library Functions 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 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. Creat-
     ing 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 position indicator
     will be placed at 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 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 (garbage) after a
     file is closed.

     A file may	be subsequently	reopened, by the same or another program exe-
     cution, 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 out-
     put streams are flushed) before program termination.  Other methods of
     program termination may not close files properly and hence	buffered out-
     put may be	lost.  In particular, _exit(2) does not	flush stdio files.
     Neither does an exit due to a signal.  Buffers are	flushed	by abort(3) as
     required by POSIX,	although previous implementations did not.

     This implementation makes no distinction between ``text'' and ``binary''
     streams.  In effect, all streams are binary.  No translation is performed
     and no extra padding appears on any stream.

     At	program	startup, three streams are predefined and need not be opened
     explicitly:
	   +o   standard	input (for reading conventional	input),
	   +o   standard	output (for writing conventional output), and
	   +o   standard	error (for writing diagnostic output).
     These streams are abbreviated stdin, stdout and stderr.  Initially, the
     standard error stream is unbuffered; the standard input and output
     streams are fully buffered	if and only if the streams do not refer	to an
     interactive or ``terminal'' device, as determined by the isatty(3)	func-
     tion.  In fact, all freshly-opened	streams	that refer to terminal devices
     default to	line buffering,	and pending output to such streams is written
     automatically whenever such an input stream is read.  Note	that this
     applies only to ``true reads''; if	the read request can be	satisfied by
     existing buffered data, no	automatic flush	will occur.  In	these cases,
     or	when 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.
     Alternatively, these defaults may be modified via the setvbuf(3) func-
     tion.

     The stdio library is a part of the	library	libc and routines are automat-
     ically loaded as needed by	the C compiler.	 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 with-
     out first removing	their current definitions with #undef: BUFSIZ, EOF,
     FILENAME_MAX, FOPEN_MAX, L_cuserid, L_ctermid, L_tmpnam, NULL, P_tmpdir,
     SEEK_CUR, SEEK_END, SEEK_SET, TMP_MAX, clearerr, feof, ferror, fileno,
     fropen, fwopen, getc, getchar, putc, putchar, stderr, stdin, stdout,
     vfscanf.  Function	versions of the	macro functions	clearerr(), feof(),
     ferror(), fileno(), getc(), getchar(), putc(), and	putchar() exist	and
     will be used if the macro definitions are explicitly removed.

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

BUGS
     The standard buffered functions do	not interact well with certain other
     library and system	functions, especially vfork(2).

STANDARDS
     The stdio library conforms	to ANSI	X3.159-1989 (``ANSI C89'').

LIST OF	FUNCTIONS
     Function	    Description
     asprintf	    formatted output conversion
     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
     fgetln	    get	a line from a 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
     funopen	    open a stream
     fwopen	    open 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
     mkdtemp	    create unique temporary file
     mkstemp	    create unique temporary file
     mktemp	    create unique temporary file
     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
     snprintf	    formatted output conversion
     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
     vasprintf	    formatted output conversion
     vfprintf	    formatted output conversion
     vfscanf	    input format conversion
     vprintf	    formatted output conversion
     vscanf	    input format conversion
     vsnprintf	    formatted output conversion
     vsprintf	    formatted output conversion
     vsscanf	    input format conversion

4th Berkeley Distribution	April 19, 1994	     4th Berkeley Distribution

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | BUGS | STANDARDS | LIST OF FUNCTIONS

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