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, 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 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 otherwise unintelligible FILE data.