stdio(3)

NAME

     stdio - standard buffered input/output package

SYNOPSIS

     #include <stdio.h>

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

DESCRIPTION

     The functions  in  the  standard  I/O  library  constitute  a  user-level
     buffering  scheme.  The in-line macros getc and putc(3) 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(3)  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 the standard I/O manual pages 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:  clearerr, getc, getchar, putc, putchar, feof, ferror,
     fileno.

SEE ALSO

     open(2), close(2), read(2),  write(2),  fclose(3),  ferror(3),  fopen(3),
     fread(3),   fseek(3),  getc(3),  gets(3),  printf(3),  putc(3),  puts(3),
     scanf(3), setbuf(3), ungetc(3).

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(3) 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 fork and abort.

LIST OF FUNCTIONS

     Name        Appears on Page    Description

     clearerr      ferror(3)    stream status inquiries
     fclose        fclose(3)    close or flush a stream
     fdopen        fopen(3)     open a stream
     feof          ferror(3)    stream status inquiries
     ferror        ferror(3)    stream status inquiries
     fflush        fclose(3)    close or flush a stream
     fgetc         getc(3)      get character or word from stream
     fgets         gets(3)      get a string from a stream
     fileno        ferror(3)    stream status inquiries
     fopen         fopen(3)     open a stream
     fprintf       printf(3)    formatted output conversion
     fputc         putc(3)      put character or word on a stream
     fputs         puts(3)      put a string on a stream
     fread         fread(3)     buffered binary input/output
     freopen       fopen(3)     open a stream
     fscanf        scanf(3)     formatted input conversion
     fseek         fseek(3)     reposition a stream
     ftell         fseek(3)     reposition a stream
     fwrite        fread(3)     buffered binary input/output
     getc          getc(3)      get character or word from stream
     getchar       getc(3)      get character or word from stream
     gets          gets(3)      get a string from a stream
     getw          getc(3)      get character or word from stream
     printf        printf(3)    formatted output conversion
     putc          putc(3)      put character or word on a stream
     putchar       putc(3)      put character or word on a stream
     puts          puts(3)      put a string on a stream
     putw          putc(3)      put character or word on a stream
     rewind        fseek(3)     reposition a stream
     scanf         scanf(3)     formatted input conversion
     setbuf        setbuf(3)    assign buffering to a stream
     setvbuf       setbuf(3)    assign buffering to a stream
     snprintf      printf(3)    formatted output conversion
     sprintf       printf(3)    formatted output conversion
     sscanf        scanf(3)     formatted input conversion
     ungetc        ungetc(3)    push character back into input stream
     vfprintf      printf(3)    formatted output conversion
     vfscanf       scanf(3)     formatted input conversion
     vprintf       printf(3)    formatted output conversion
     vscanf        scanf(3)     formatted input conversion
     vsnprintf     printf(3)    formatted output conversion
     vsprintf      printf(3)    formatted output conversion
     vsscanf       scanf(3)     formatted input conversion