STDIO(3S)                            BSD                             STDIO(3S)



NAME
     stdio - standard buffered input/output package

SYNOPSIS
     #include <stdio.h>

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

DESCRIPTION
     The functions described in section 3S constitute a user-level buffering
     scheme.  The in-line macros getc and putc(3S) handle characters quickly.
     The higher level routines gets, fgets, scanf, fscanf, fread, puts, fputs,
     printf, fprintf, fwrite all use getc and putc; they can be freely
     intermixed.

     A file with associated buffering is called a stream, and is declared to
     be a pointer to a defined type FILE.  fopen(3S) creates certain
     descriptive data for a stream and returns a pointer to designate the
     stream in all further transactions.  There are three normally open
     streams with constant pointers declared in the include file and
     associated with the standard open files:

     stdin     standard input file
     stdout    standard output file
     stderr    standard error file

     A constant "pointer" NULL (0) designates no stream at all.

     An integer constant EOF (-1) is returned upon end of file or error by
     integer functions that deal with streams.

     Any routine that uses the standard input/output package must include the
     header file <stdio.h> of pertinent macro definitions.  The functions and
     constants mentioned in sections labeled 3S are declared in the include
     file and need no further declaration.  The constants, and the following
     "functions" are implemented as macros; redeclaration of these names is
     perilous:  getc, getchar, putc, putchar, feof, ferror, fileno.

SEE ALSO
     open(2), close(2), read(2), write(2), fread(3S), fseek(3S), f*(3S)

DIAGNOSTICS
     The value EOF is returned uniformly to indicate that a FILE pointer has
     not been initialized with fopen, input (output) has been attempted on an
     output (input) stream, or a FILE pointer designates corrupt or otherwise
     unintelligible FILE data.

     For purposes of efficiency, this implementation of the standard library
     has been changed to line buffer output to a terminal by default and
     attempts to do this transparently by flushing the output whenever a
     read(2) from the standard input is necessary.  This is almost always
     transparent, but may cause confusion or malfunctioning of programs which
     use standard i/o routines but use read(2) themselves to read from the
     standard input.

     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(3S) the
     standard output before going off and computing so that the output will
     appear.

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

LIST OF FUNCTIONS
     Name        Appears on Page    Description

     clearerr      ferror(3S)   stream status inquiries
     fclose        fclose(3S)   close or flush a stream
     fdopen        fopen(3S)    open a stream
     feof          ferror(3S)   stream status inquiries
     ferror        ferror(3S)   stream status inquiries
     fflush        fclose(3S)   close or flush a stream
     fgetc         getc(3S)     get character or word from stream
     fgets         gets(3S)     get a string from a stream
     fileno        ferror(3S)   stream status inquiries
     fopen         fopen(3S)    open a stream
     fprintf       printf(3S)   formatted output conversion
     fputc         putc(3S)     put character or word on a stream
     fputs         puts(3S)     put a string on a stream
     fread         fread(3S)    buffered binary input/output
     freopen       fopen(3S)    open a stream
     fscanf        scanf(3S)    formatted input conversion
     fseek         fseek(3S)    reposition a stream
     ftell         fseek(3S)    reposition a stream
     fwrite        fread(3S)    buffered binary input/output
     getc          getc(3S)     get character or word from stream
     getchar       getc(3S)     get character or word from stream
     gets          gets(3S)     get a string from a stream
     getw          getc(3S)     get character or word from stream
     printf        printf(3S)   formatted output conversion
     putc          putc(3S)     put character or word on a stream
     putchar       putc(3S)     put character or word on a stream
     puts          puts(3S)     put a string on a stream
     putw          putc(3S)     put character or word on a stream
     rewind        fseek(3S)    reposition a stream
     scanf         scanf(3S)    formatted input conversion
     setbuf        setbuf(3S)   assign buffering to a stream
     setbuffer     setbuf(3S)   assign buffering to a stream
     setlinebuf    setbuf(3S)   assign buffering to a stream
     sprintf       printf(3S)   formatted output conversion
     sscanf        scanf(3S)    formatted input conversion
     tmpfile       tmpfile(3S)  create a temporary file
     tmpnam        tmpnam(3S)   create a name for a temporary file
     ungetc        ungetc(3S)   push character back into input stream

NOTES
     To be backward compatible, programs compiled with the

          -A ansi

     option (see cc(1)) must contain the directives

          #define _CLASSIC_IOB
          #define _BSD_SOURCE

     before any #include directives.