term% cat index.txt STDIO(3S) STDIO(3S)
NAME
stdio - standard buffered input/output package
SYNOPSIS
#include <stdio.h>
FILE *stdin;
FILE *stdout;
FILE *stderr;
DESCRIPTION
The functions described in Sections 3S constitute an efficient user-
level buffering scheme. The in-line macros getc and putc(3) handle
characters quickly. The higher level routines gets, fgets, scanf, fs‐
canf, 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 descrip‐
tive 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 func‐
tions 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)
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 oth‐
erwise unintelligible FILE data.
STDIO(3S)