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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.
       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 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 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 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
       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, 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
       standard  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
       automatically  loaded  as needed by the compilers cc(1) and pc(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.

       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,
       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    return the integer descriptor of the argument stream

       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

       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

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

                                  2001-12-26                          STDIO(3)