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STDIO(3) 			   BSD Library Functions Manual 			   STDIO(3) 

NAME
     stdio -- standard input/output library functions

LIBRARY
     Standard C Library (libc, -lc)

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.  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 posi-
     tioned 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 out-
     put takes place as if all characters were written by successive calls to the   fputc(3)  func-
     tion.

     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 dis-
     associated 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 execution, and its con-
     tents 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 may not close files properly and hence buffered output may be lost.  In particu-
     lar,   _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)  function.  In fact, all freshly-opened streams that refer to terminal devices
     default to line buffering, and pending output to such streams is written automatically when-
     ever 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)  function.

     The stdio library is a part of the library libc and routines are automatically 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 without first removing
     their current definitions with #undef: BUFSIZ, EOF, FILENAME_MAX, FOPEN_MAX, L_ctermid,
     L_cuserid, L_tmpnam, NULL, P_tmpdir, SEEK_CUR, SEEK_END, SEEK_SET, TMP_MAX, clearerr,
     clearerr_unlocked, feof, feof_unlocked, ferror, ferror_unlocked, fileno, fileno_unlocked,
     fropen, fwopen, getc, getc_unlocked, getchar, getchar_unlocked, putc, putc_unlocked,
     putchar, putchar_unlocked, stderr, stdin and stdout.  Function versions of the macro func-
     tions clearerr, clearerr_unlocked, feof, feof_unlocked, ferror, ferror_unlocked, fileno,
     fileno_unlocked, getc, getc_unlocked, getchar, getchar_unlocked, putc, putc_unlocked,
     putchar, and putchar_unlocked exist and will be used if the macro definitions are explicitly
     removed.

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

STANDARDS
     The stdio library conforms to ISO/IEC 9899:1999 (``ISO C99'').

LIST OF FUNCTIONS
     Function	    Description
     asprintf	    formatted output conversion
     clearerr	    check and reset stream status
     dprintf	    formatted output conversion
     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
     fgetwc	    get next wide character from input stream
     fgetws	    get a line of wide characters 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
     fputwc	    output a wide character to a stream
     fputws	    output a line of wide characters 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
     fwide	    set/get orientation of stream
     fwopen	    open a stream
     fwprintf	    formatted wide character output conversion
     fwrite	    binary stream input/output
     getc	    get next character or word from input stream
     getchar	    get next character or word from input stream
     getdelim	    get a line from a stream
     getline	    get a line from a stream
     gets	    get a line from a stream
     getw	    get next character or word from input stream
     getwc	    get next wide character from input stream
     getwchar	    get next wide character from input stream
     mkdtemp	    create unique temporary directory
     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
     putwc	    output a wide character to a stream
     putwchar	    output a wide character 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
     swprintf	    formatted wide character output conversion
     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
     ungetwc	    un-get wide character from input stream
     vasprintf	    formatted output conversion
     vdprintf	    formatted output conversion
     vfprintf	    formatted output conversion
     vfscanf	    input format conversion
     vfwprintf	    formatted wide character output conversion
     vprintf	    formatted output conversion
     vscanf	    input format conversion
     vsnprintf	    formatted output conversion
     vsprintf	    formatted output conversion
     vsscanf	    input format conversion
     vswprintf	    formatted wide character output conversion
     vwprintf	    formatted wide character output conversion
     wprintf	    formatted wide character output conversion

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

BSD					  March 3, 2009 				      BSD
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