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NAME    [Toc]    [Back]

     stdio - standard input/output library functions

LIBRARY    [Toc]    [Back]

     Standard C Library (libc, -lc)

SYNOPSIS    [Toc]    [Back]

     #include <stdio.h>
     FILE *stdin;
     FILE *stdout;
     FILE *stderr;

DESCRIPTION    [Toc]    [Back]

     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

     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, the position 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 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

     This implementation needs and 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
           +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 whenever an 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.a and routines are automatically
 loaded as needed by compilers such as cc(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(),
     freopen(), 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.

SEE ALSO    [Toc]    [Back]

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

STANDARDS    [Toc]    [Back]

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

LIST OF FUNCTIONS    [Toc]    [Back]

     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
     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
     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
     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 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
     getwc          get next wide character from input stream
     getwchar       get next wide character from input stream
     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
     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
     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

BUGS    [Toc]    [Back]

     The standard buffered functions do not interact well with certain other
     library and system functions, especially vfork(2) and abort(3).

BSD                             April 19, 1994                             BSD
[ Back ]
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